Add files using upload-large-folder tool

snapshots/jotego_jtcores_pr1087/modules/jtframe/asm/z80/Makefile

@@ -0,0 +1,5 @@
+jtTinyBasic.o: jtTinyBasic.asm
+	z80asm jtTinyBasic.asm -o jtTinyBasic.o -l 2> jtTinyBasic.lst
+
+clean:
+	rm -f jtTinyBasic.o jtTinyBasic.lst

snapshots/jotego_jtcores_pr1087/modules/jtframe/asm/z80/TinyBasic_2.0g.asm

@@ -0,0 +1,1780 @@
+;*************************************************************
+;
+;                 TINY BASIC FOR ZILOG Z80
+;                       VERSION 2.0
+;                     BY LI-CHEN WANG
+;
+;                  MODIFIED AND TRANSLATED
+;                    TO INTEL MNEMONICS
+;                     BY ROGER RAUSKOLB
+;                      10 OCTOBER,1976
+;
+;                  MODIFIED AND TRANSLATED
+;                    TO ZILOG MNEMONICS
+;                      BY DOUG GABBARD
+;            www.retrodepot.net
+;
+;           RELEASED TO THE PUBLIC
+;                      10 OCTOBER,2017
+;                  YEAH, 41 YEARS LATER....
+;
+;                         @COPYLEFT
+;                   ALL WRONGS RESERVED
+;
+;*************************************************************
+; This code is derived from the original 8080 Tiny Basic.
+; It was first compiled in 8080 Mnemonics, then disassembled
+; into Zilog Mnemonics.  And then checked against the original
+; to ensure accuracy.  It was then partially enhanced with z80
+; specific code. And once done, it was then modified to work
+; with the G80-S Micro Computer. However, that portion of the
+; code has been left out in order to make this code a little
+; more portable.  There are only three routines that one needs
+; to write, and specifing the serial port's I/O address, in
+; order to make this version work with your own DIY computer.
+; Those routines can be found at the end of the source code.
+;
+; I hope you find good use for this relic. However, I would
+; ask that if you do find use for it, please put a reference
+; to me in your work. And please, distribute freely.
+;*************************************************************
+
+SerialPort: EQU 00H     ;This is for your I/0
+
+
+SPACE:          EQU     020H            ; Space
+TAB:            EQU     09H             ; HORIZONTAL TAB
+CTRLC:          EQU     03H             ; Control "C"
+CTRLG:          EQU     07H             ; Control "G"
+BKSP:           EQU     08H             ; Back space
+LF:             EQU     0AH             ; Line feed
+CS:             EQU     0CH             ; Clear screen
+CR:             EQU     0DH             ; Carriage return
+CTRLO:          EQU     0FH             ; Control "O"
+CTRLQ:          EQU     011H            ; Control "Q"
+CTRLR:          EQU     012H            ; Control "R"
+CTRLS:          EQU     013H            ; Control "S"
+CTRLU:          EQU     015H            ; Control "U"
+ESC:            EQU     01BH            ; Escape
+DEL:            EQU     07FH            ; Delete
+
+STACK:          EQU     0FFFFH          ; STACK
+OCSW:           EQU     08000H          ;SWITCH FOR OUTPUT
+CURRNT:         EQU     OCSW+1          ;POINTS FOR OUTPUT
+STKGOS:         EQU     OCSW+3          ;SAVES SP IN 'GOSUB'
+VARNXT:         EQU     OCSW+5          ;TEMP STORAGE
+STKINP:         EQU     OCSW+7          ;SAVES SP IN 'INPUT'
+LOPVAR:         EQU     OCSW+9          ;'FOR' LOOP SAVE AREA
+LOPINC:         EQU     OCSW+11         ;INCREMENT
+LOPLMT:         EQU     OCSW+13         ;LIMIT
+LOPLN:          EQU     OCSW+15         ;LINE NUMBER
+LOPPT:          EQU     OCSW+17         ;TEXT POINTER
+RANPNT:         EQU     OCSW+19         ;RANDOM NUMBER POINTER
+TXTUNF:         EQU     OCSW+21         ;->UNFILLED TEXT AREA
+TXTBGN:         EQU     OCSW+23         ;TEXT SAVE AREA BEGINS
+
+TXTEND:         EQU     0FF00H          ;TEXT SAVE AREA ENDS
+
+
+;*************************************************************
+; *** ZERO PAGE SUBROUTINES ***
+;
+; THE Z80 INSTRUCTION SET ALLOWS FOR 8 ROUTINES IN LOW MEMORY
+; THAT MAY BE CALLED BY RST 00H, 08H, 10H, 18H, 20H, 28H, 30H,
+; AND 38H.  THIS IS A ONE BYTE INSTRUCTION, AND IS FUNCTIONALLY
+; SIMILAR TO THE THREE BYTE INSTRUCTION 'CALL XXXX'. TINY BASIC
+; WILL USE THE RST INSTRUCTION FOR THE 7 MOST FREQUENTLY USED
+; SUBROUTINES. TWO OTHER SUBROUTINES (CRLF & TSTNUM) ARE ALSO
+; IN THIS SECTION. THEY CAN BE REACHED WITH 'CALL'.
+;*************************************************************
+
+DWA:    MACRO WHERE
+        DB   (WHERE >> 8) + 128
+        DB   WHERE & 0FFH
+        ENDM
+
+        ORG  0000H
+
+START:
+        LD SP,STACK                     ;*** COLD START ***
+        LD A,0FFH
+        JP INIT
+
+RST08:  EX (SP),HL                      ;*** TSTC OR RST 08H ***
+        RST 28H                         ;IGNORE BLANKS AND
+        CP (HL)                         ;TEST CHARACTER
+        JP TC1                          ;REST OF THIS IS AT TC1
+
+CRLF:
+        LD A,CR                         ;*** CRLF ***
+
+RST10:  PUSH AF                         ;*** OUTC OR RST 10H ***
+        LD A,(OCSW)                     ;PRINT CHARACTER ONLY
+        OR A                            ;IF OCSW SWITCH IS ON
+        JP OUTC             ;REST OF THIS AT OUTC
+
+RST18:  CALL EXPR2                      ;*** EXPR OR RST 18H ***
+        PUSH HL                         ;EVALUATE AN EXPRESSION
+        JP EXPR1                        ;REST OF IT AT EXPR1
+        DB 'W'
+
+RST20:  LD A,H                          ;*** COMP OR RST 20H ***
+        CP D                            ;COMPARE HL WITH DE
+        RET NZ                          ;RETURN CORRECT C AND
+        LD A,L                          ;Z FLAGS
+        CP E                            ;BUT OLD A IS LOST
+        RET
+        DB 'AN'
+
+SS1:
+RST28:  LD A,(DE)                       ;*** IGNBLK/RST 28H ***
+        CP 20H                          ;IGNORE BLANKS
+        RET NZ                          ;IN TEXT (WHERE DE->)
+        INC DE                          ;AND RETURN THE FIRST
+        JP SS1                          ;NON-BLANK CHAR. IN A
+
+RST30:  POP AF                          ;*** FINISH/RST 30H ***
+        CALL FIN                        ;CHECK END OF COMMAND
+        JP QWHAT                        ;PRINT "WHAT?" IF WRONG
+        DB 'G'
+
+RST38:  RST 28H                         ;*** TSTV OR RST 38H ***
+        SUB 40H                         ;TEST VARIABLES
+        RET C                           ;C:NOT A VARIABLE
+        JR NZ,TV1                       ;NOT "@" ARRAY
+        INC DE                          ;IT IS THE "@" ARRAY
+        CALL PARN                       ;@ SHOULD BE FOLLOWED
+        ADD HL,HL                       ;BY (EXPR) AS ITS INDEX
+        JR C,QHOW                       ;IS INDEX TOO BIG?
+        PUSH DE                         ;WILL IT OVERWRITE
+        EX DE,HL                        ;TEXT?
+        CALL SIZE                       ;FIND SIZE OF FREE
+        RST 20H                         ;AND CHECK THAT
+        JP C,ASORRY                     ;IF SO, SAY "SORRY"
+        LD HL,VARBGN                    ;IF NOT GET ADDRESS
+        CALL SUBDE                      ;OF @(EXPR) AND PUT IT
+        POP DE                          ;IN HL
+        RET                             ;C FLAG IS CLEARED
+
+TV1:
+        CP 1BH                          ;NOT @, IS IT A TO Z?
+        CCF                             ;IF NOT RETURN C FLAG
+        RET C
+        INC DE                          ;IF A THROUGH Z
+        LD HL,VARBGN                    ;COMPUTE ADDRESS OF
+        RLCA                            ;THAT VARIABLE
+        ADD A,L                         ;AND RETURN IT IN HL
+        LD L,A                          ;WITH C FLAG CLEARED
+        LD A,00H
+        ADC A,H
+        LD H,A
+        RET
+
+TC1:
+        INC HL                          ;COMPARE THE BYTE THAT
+        JR Z,TC2                        ;FOLLOWS THE RST INST.
+        PUSH BC                         ;WITH THE TEXT (DE->)
+        LD C,(HL)                       ;IF NOT =, ADD THE 2ND
+        LD B,00H                        ;BYTE THAT FOLLOWS THE
+        ADD HL,BC                       ;RST TO THE OLD PC
+        POP BC                          ;I.E., DO A RELATIVE
+        DEC DE                          ;JUMP IF NOT =
+
+TC2:
+        INC DE                          ;IF =, SKIP THOSE BYTES
+        INC HL                          ;AND CONTINUE
+        EX (SP),HL
+        RET
+
+TSTNUM:
+        LD HL,0000H                     ;*** TSTNUM ***
+        LD B,H                          ;TEST IF THE TEXT IS
+        RST 28H                         ;A NUMBER
+
+TN1:
+        CP 30H                          ;IF NOT, RETURN 0 IN
+        RET C                           ;B AND HL
+        CP 3AH                          ;IF NUMBERS, CONVERT
+        RET NC                          ;TO BINARY IN HL AND
+        LD A,0F0H                       ;SET B TO # OF DIGITS
+        AND H                           ;IF H>255, THERE IS NO
+        JR NZ,QHOW                      ;ROOM FOR NEXT DIGIT
+        INC B                           ;B COUNTS # OF DIGITS
+        PUSH BC
+        LD B,H                          ;HL=10*HL+(NEW DIGIT)
+        LD C,L
+        ADD HL,HL                       ;WHERE 10* IS DONE BY
+        ADD HL,HL                       ;SHIFT AND ADD
+        ADD HL,BC
+        ADD HL,HL
+        LD A,(DE)                       ;AND (DIGIT) IS FROM
+        INC DE                          ;STRIPPING THE ASCII
+        AND 0FH                         ;CODE
+        ADD A,L
+        LD L,A
+        LD A,00H
+        ADC A,H
+        LD H,A
+        POP BC
+        LD A,(DE)                       ;DO THIS DIGIT AFTER
+        JP P,TN1                        ;DIGIT. S SAYS OVERFLOW
+
+QHOW:
+        PUSH DE                         ;*** ERROR "HOW?" ***
+AHOW:
+        LD DE,HOW
+        JP ERROR_ROUTINE
+
+
+HOW:    DB "HOW?",CR
+OK:     DB "OK",CR
+WHAT:   DB "WHAT?",CR
+SORRY:  DB "SORRY",CR
+
+;*************************************************************
+;
+; *** MAIN ***
+;
+; THIS IS THE MAIN LOOP THAT COLLECTS THE TINY BASIC PROGRAM
+; AND STORES IT IN THE MEMORY.
+;
+; AT START, IT PRINTS OUT "(CR)OK(CR)", AND INITIALIZES THE
+; STACK AND SOME OTHER INTERNAL VARIABLES.  THEN IT PROMPTS
+; ">" AND READS A LINE.  IF THE LINE STARTS WITH A NON-ZERO
+; NUMBER, THIS NUMBER IS THE LINE NUMBER.  THE LINE NUMBER
+; (IN 16 BIT BINARY) AND THE REST OF THE LINE (INCLUDING CR)
+; IS STORED IN THE MEMORY.  IF A LINE WITH THE SAME LINE
+; NUMBER IS ALREADY THERE, IT IS REPLACED BY THE NEW ONE.  IF
+; THE REST OF THE LINE CONSISTS OF A CR ONLY, IT IS NOT STORED
+; AND ANY EXISTING LINE WITH THE SAME LINE NUMBER IS DELETED.
+;
+; AFTER A LINE IS INSERTED, REPLACED, OR DELETED, THE PROGRAM
+; LOOPS BACK AND ASKS FOR ANOTHER LINE.  THIS LOOP WILL BE
+; TERMINATED WHEN IT READS A LINE WITH ZERO OR NO LINE
+; NUMBER; AND CONTROL IS TRANSFERED TO "DIRECT".
+;
+; TINY BASIC PROGRAM SAVE AREA STARTS AT THE MEMORY LOCATION
+; LABELED "TXTBGN" AND ENDS AT "TXTEND".  WE ALWAYS FILL THIS
+; AREA STARTING AT "TXTBGN", THE UNFILLED PORTION IS POINTED
+; BY THE CONTENT OF A MEMORY LOCATION LABELED "TXTUNF".
+;
+; THE MEMORY LOCATION "CURRNT" POINTS TO THE LINE NUMBER
+; THAT IS CURRENTLY BEING INTERPRETED.  WHILE WE ARE IN
+; THIS LOOP OR WHILE WE ARE INTERPRETING A DIRECT COMMAND
+; (SEE NEXT SECTION). "CURRNT" SHOULD POINT TO A 0.
+;*************************************************************
+
+RSTART:
+        LD SP,STACK
+
+ST1:
+        CALL CRLF                       ;AND JUMP TO HERE
+        LD DE,OK                        ;DE->STRING
+        SUB A                           ;A=0
+        CALL PRTSTG                     ;PRINT STRING UNTIL CR
+        LD HL,ST2+1                     ;LITERAL 0
+        LD (CURRNT),HL                  ;CURRENT->LINE # = 0
+
+ST2:
+        LD HL,0000H
+        LD (LOPVAR),HL
+        LD (STKGOS),HL
+
+ST3:
+        LD A,'>'                        ;PROMPT '>' AND
+        CALL GETLN                      ;READ A LINE
+        PUSH DE                         ;DE->END OF LINE
+        LD DE,BUFFER                    ;DE->BEGINNING OF LINE
+        CALL TSTNUM                     ;TEST IF IT IS A NUMBER
+        RST 28H
+        LD A,H                          ;HL=VALUE OF THE # OR
+        OR L                            ;0 IF NO # WAS FOUND
+        POP BC                          ;BC->END OF LINE
+        JP Z,DIRECT
+        DEC DE                          ;BACKUP DE AND SAVE
+        LD A,H                          ;VALUE OF LINE # THERE
+        LD (DE),A
+        DEC DE
+        LD A,L
+        LD (DE),A
+        PUSH BC                         ;BC,DE->BEGIN, END
+        PUSH DE
+        LD A,C
+        SUB E
+
+        PUSH AF                         ;A=# OF BYTES IN LINE
+        CALL FNDLN                      ;FIND THIS LINE IN SAVE
+        PUSH DE                         ;AREA, DE->SAVE AREA
+        JR NZ,ST4                       ;NZ:NOT FOUND, INSERT
+        PUSH DE                         ;Z:FOUND, DELETE IT
+        CALL FNDNXT                     ;FIND NEXT LINE
+                                        ;DE->NEXT LINE
+        POP BC                          ;BC->LINE TO BE DELETED
+        LD HL,(TXTUNF)                  ;HL->UNFILLED SAVE AREA
+        CALL MVUP                       ;MOVE UP TO DELETE
+        LD H,B                          ;TXTUNF->UNFILLED ARA
+        LD L,C
+        LD (TXTUNF),HL                  ;UPDATE
+
+ST4:
+        POP BC                          ;GET READY TO INSERT
+        LD HL,(TXTUNF)                  ;BUT FIRST CHECK IF
+        POP AF                          ;THE LENGTH OF NEW LINE
+        PUSH HL                         ;IS 3 (LINE # AND CR)
+        CP 03H                          ;THEN DO NOT INSERT
+        JR Z,RSTART                     ;MUST CLEAR THE STACK
+        ADD A,L                         ;COMPUTE NEW TXTUNF
+        LD L,A
+        LD A,00H
+        ADC A,H
+        LD H,A                          ;HL->NEW UNFILLED AREA
+        LD DE,TXTEND                    ;CHECK TO SEE IF THERE
+        RST 20H                         ;IS ENOUGH SPACE
+        JP NC,QSORRY                    ;SORRY, NO ROOM FOR IT
+        LD (TXTUNF),HL                  ;OK, UPDATE TXTUNF
+        POP DE                          ;DE->OLD UNFILLED AREA
+        CALL MVDOWN
+        POP DE                          ;DE->BEGIN, HL->END
+        POP HL
+        CALL MVUP                       ;MOVE NEW LINE TO SAVE
+        JR ST3                          ;AREA
+
+;*************************************************************
+;
+; WHAT FOLLOWS IS THE CODE TO EXECUTE DIRECT AND STATEMENT
+; COMMANDS.  CONTROL IS TRANSFERED TO THESE POINTS VIA THE
+; COMMAND TABLE LOOKUP CODE OF 'DIRECT' AND 'EXEC' IN LAST
+; SECTION.  AFTER THE COMMAND IS EXECUTED, CONTROL IS
+; TRANSFERED TO OTHERS SECTIONS AS FOLLOWS:
+;
+; FOR 'LIST', 'NEW', AND 'STOP': GO BACK TO 'RSTART'
+; FOR 'RUN': GO EXECUTE THE FIRST STORED LINE IF ANY, ELSE
+; GO BACK TO 'RSTART'.
+; FOR 'GOTO' AND 'GOSUB': GO EXECUTE THE TARGET LINE.
+; FOR 'RETURN' AND 'NEXT': GO BACK TO SAVED RETURN LINE.
+; FOR ALL OTHERS: IF 'CURRENT' -> 0, GO TO 'RSTART', ELSE
+; GO EXECUTE NEXT COMMAND.  (THIS IS DONE IN 'FINISH'.)
+;*************************************************************
+;
+; *** NEW *** STOP *** RUN (& FRIENDS) *** & GOTO ***
+;
+; 'NEW(CR)' SETS 'TXTUNF' TO POINT TO 'TXTBGN'
+;
+; 'STOP(CR)' GOES BACK TO 'RSTART'
+;
+; 'RUN(CR)' FINDS THE FIRST STORED LINE, STORE ITS ADDRESS (IN
+; 'CURRENT'), AND START EXECUTE IT.  NOTE THAT ONLY THOSE
+; COMMANDS IN TAB2 ARE LEGAL FOR STORED PROGRAM.
+;
+; THERE ARE 3 MORE ENTRIES IN 'RUN':
+; 'RUNNXL' FINDS NEXT LINE, STORES ITS ADDR. AND EXECUTES IT.
+; 'RUNTSL' STORES THE ADDRESS OF THIS LINE AND EXECUTES IT.
+; 'RUNSML' CONTINUES THE EXECUTION ON SAME LINE.
+;
+; 'GOTO EXPR(CR)' EVALUATES THE EXPRESSION, FIND THE TARGET
+; LINE, AND JUMP TO 'RUNTSL' TO DO IT.
+;*************************************************************
+
+NEW:
+        CALL ENDCHK                     ;*** NEW(CR) ***
+        LD HL,TXTBGN
+        LD (TXTUNF),HL
+STOP:
+        CALL ENDCHK                     ;*** STOP(CR) ***
+        JP RSTART
+RUN:
+        CALL ENDCHK                     ;*** RUN(CR) ***
+        LD DE,TXTBGN                    ;FIRST SAVED LINE
+RUNNXL:
+        LD HL,00H                       ;*** RUNNXL ***
+        CALL FNDLP                      ;FIND WHATEVER LINE #
+        JP C,RSTART                     ;C:PASSED TXTUNF, QUIT
+RUNTSL:
+        EX DE,HL                        ;*** RUNTSL ***
+        LD (CURRNT),HL                  ;SET 'CURRENT'->LINE #
+        EX DE,HL
+        INC DE                          ;BUMP PASS LINE #
+        INC DE
+RUNSML:
+        CALL CHKIO                      ;*** RUNSML ***
+        LD HL,TAB2-1                    ;FIND COMMAND IN TAB2
+        JP EXEC                         ;AND EXECUTE IT
+GOTO:
+        RST 18H                         ;*** GOTO EXPR ***
+        PUSH DE                         ;SAVE FOR ERROR ROUTINE
+        CALL ENDCHK                     ;MUST FIND A CR
+        CALL FNDLN                      ;FIND THE TARGET LINE
+        JP NZ,AHOW                      ;NO SUCH LINE #
+        POP AF                          ;CLEAR THE PUSH DE
+        JR RUNTSL                       ;GO DO IT
+
+;*************************************************************
+;
+; *** LIST *** & PRINT ***
+;
+; LIST HAS TWO FORMS:
+; 'LIST(CR)' LISTS ALL SAVED LINES
+; 'LIST #(CR)' START LIST AT THIS LINE #
+; YOU CAN STOP THE LISTING BY CONTROL C KEY
+;
+; PRINT COMMAND IS 'PRINT ....;' OR 'PRINT ....(CR)'
+; WHERE '....' IS A LIST OF EXPRESIONS, FORMATS, BACK-
+; ARROWS, AND STRINGS.  THESE ITEMS ARE SEPERATED BY COMMAS.
+;
+; A FORMAT IS A POUND SIGN FOLLOWED BY A NUMBER.  IT CONTROLS
+; THE NUMBER OF SPACES THE VALUE OF A EXPRESION IS GOING TO
+; BE PRINTED.  IT STAYS EFFECTIVE FOR THE REST OF THE PRINT
+; COMMAND UNLESS CHANGED BY ANOTHER FORMAT.  IF NO FORMAT IS
+; SPECIFIED, 6 POSITIONS WILL BE USED.
+;
+; A STRING IS QUOTED IN A PAIR OF SINGLE QUOTES OR A PAIR OF
+; DOUBLE QUOTES.
+;
+; A BACK-ARROW MEANS GENERATE A (CR) WITHOUT (LF)
+;
+; A (CRLF) IS GENERATED AFTER THE ENTIRE LIST HAS BEEN
+; PRINTED OR IF THE LIST IS A NULL LIST.  HOWEVER IF THE LIST
+; ENDED WITH A COMMA, NO (CRLF) IS GENERATED.
+;*************************************************************
+
+LIST:
+        CALL TSTNUM                     ;TEST IF THERE IS A #
+        CALL ENDCHK                     ;IF NO # WE GET A 0
+        CALL FNDLN                      ;FIND THIS OR NEXT LINE
+LS1:
+        JP C,RSTART                     ;C:PASSED TXTUNF
+        CALL PRTLN                      ;PRINT THE LINE
+        CALL CHKIO                      ;STOP IF HIT CONTROL-C
+        CALL FNDLP                      ;FIND NEXT LINE
+        JR LS1                          ;AND LOOP BACK
+PRINT:
+        LD C,06H                        ;C = # OF SPACES
+        RST 08H                         ;F NULL LIST & ";"
+        DB 3BH
+        DB PR2-$-1
+        CALL CRLF                       ;GIVE CR-LF AND
+        JR RUNSML                       ;CONTINUE SAME LINE
+PR2:
+        RST 08H                         ;IF NULL LIST (CR)
+        DB CR
+        DB PR0-$-1
+        CALL CRLF                       ;ALSO GIVE CR-LF AND
+        JR RUNNXL                       ;GO TO NEXT LINE
+PR0:
+        RST 08H                         ;ELSE IS IT FORMAT?
+        DB '#'
+        DB PR1-$-1
+        RST 18H                         ;YES, EVALUATE EXPR.
+        LD C,L                          ;AND SAVE IT IN C
+        JR PR3                          ;LOOK FOR MORE TO PRINT
+PR1:
+        CALL QTSTG                      ;OR IS IT A STRING?
+        JR PR8                          ;IF NOT, MUST BE EXPR.
+PR3:
+        RST 08H                         ;IF ",", GO FIND NEXT
+        DB ','
+        DB PR6-$-1
+        CALL FIN                        ;IN THE LIST.
+        JR PR0                          ;LIST CONTINUES
+PR6:
+        CALL CRLF                       ;LIST ENDS
+        RST 30H
+PR8:
+        RST 18H                         ;EVALUATE THE EXPR
+        PUSH BC
+        CALL PRTNUM                     ;PRINT THE VALUE
+        POP BC
+        JR PR3                          ;MORE TO PRINT?
+
+;*************************************************************
+;
+; *** GOSUB *** & RETURN ***
+;
+; 'GOSUB EXPR;' OR 'GOSUB EXPR (CR)' IS LIKE THE 'GOTO'
+; COMMAND, EXCEPT THAT THE CURRENT TEXT POINTER, STACK POINTER
+; ETC. ARE SAVE SO THAT EXECUTION CAN BE CONTINUED AFTER THE
+; SUBROUTINE 'RETURN'.  IN ORDER THAT 'GOSUB' CAN BE NESTED
+; (AND EVEN RECURSIVE), THE SAVE AREA MUST BE STACKED.
+; THE STACK POINTER IS SAVED IN 'STKGOS', THE OLD 'STKGOS' IS
+; SAVED IN THE STACK.  IF WE ARE IN THE MAIN ROUTINE, 'STKGOS'
+; IS ZERO (THIS WAS DONE BY THE "MAIN" SECTION OF THE CODE),
+; BUT WE STILL SAVE IT AS A FLAG FOR NO FURTHER 'RETURN'S.
+;
+; 'RETURN(CR)' UNDOS EVERYTHING THAT 'GOSUB' DID, AND THUS
+; RETURN THE EXECUTION TO THE COMMAND AFTER THE MOST RECENT
+; 'GOSUB'.  IF 'STKGOS' IS ZERO, IT INDICATES THAT WE
+; NEVER HAD A 'GOSUB' AND IS THUS AN ERROR.
+;*************************************************************
+
+GOSUB:
+        CALL PUSHA                      ;SAVE THE CURRENT "FOR"
+        RST 18H                         ;PARAMETERS
+        PUSH DE                         ;AND TEXT POINTER
+        CALL FNDLN                      ;FIND THE TARGET LINE
+        JP NZ,AHOW                      ;NOT THERE. SAY "HOW?"
+        LD HL,(CURRNT)                  ;FOUND IT, SAVE OLD.
+        PUSH HL                         ;'CURRNT' OLD 'STKGOS'
+        LD HL,(STKGOS)
+        PUSH HL
+        LD HL,0000H                     ;AND LOAD NEW ONES
+        LD (LOPVAR),HL
+        ADD HL,SP
+        LD (STKGOS),HL
+        JP RUNTSL                       ;THEN RUN THAT LINE
+RETURN:
+        CALL ENDCHK                     ;THERE MUST BE A CR
+        LD HL,(STKGOS)                  ;OLD STACK POINTER
+        LD A,H                          ;0 MEANS NOT EXIST
+        OR L
+        JP Z,QWHAT                      ;SO, WE SAY: "WHAT?"
+        LD SP,HL                        ;ELSE, RESTORE IT
+        POP HL
+        LD (STKGOS),HL                  ;AND THE OLD "STKGOS"
+        POP HL
+        LD (CURRNT),HL                  ;AND THE OLD 'CURRNT'
+        POP DE                          ;OLD TEXT POINTER
+        CALL POPA                       ;OLD "FOR" PARAMETERS
+        RST 30H                         ;AND WE ARE BACK HOME
+
+;*************************************************************
+;
+; *** FOR *** & NEXT ***
+;
+; 'FOR' HAS TWO FORMS:
+; 'FOR VAR=EXP1 TO EXP2 STEP EXP3' AND 'FOR VAR=EXP1 TO EXP2'
+; THE SECOND FORM MEANS THE SAME THING AS THE FIRST FORM WITH
+; EXP3=1.  (I.E., WITH A STEP OF +1.)
+; TBI WILL FIND THE VARIABLE VAR, AND SET ITS VALUE TO THE
+; CURRENT VALUE OF EXP1.  IT ALSO EVALUATES EXP2 AND EXP3
+; AND SAVE ALL THESE TOGETHER WITH THE TEXT POINTER ETC. IN
+; THE 'FOR' SAVE AREA, WHICH CONSISTS OF 'LOPVAR', 'LOPINC',
+; 'LOPLMT', 'LOPLN', AND 'LOPPT'.  IF THERE IS ALREADY SOME-
+; THING IN THE SAVE AREA (THIS IS INDICATED BY A NON-ZERO
+; 'LOPVAR'), THEN THE OLD SAVE AREA IS SAVED IN THE STACK
+; BEFORE THE NEW ONE OVERWRITES IT.
+; TBI WILL THEN DIG IN THE STACK AND FIND OUT IF THIS SAME
+; VARIABLE WAS USED IN ANOTHER CURRENTLY ACTIVE 'FOR' LOOP.
+; IF THAT IS THE CASE, THEN THE OLD 'FOR' LOOP IS DEACTIVATED.
+; (PURGED FROM THE STACK..)
+;
+; 'NEXT VAR' SERVES AS THE LOGICAL (NOT NECESSARILLY PHYSICAL)
+; END OF THE 'FOR' LOOP.  THE CONTROL VARIABLE VAR. IS CHECKED
+; WITH THE 'LOPVAR'.  IF THEY ARE NOT THE SAME, TBI DIGS IN
+; THE STACK TO FIND THE RIGHT ONE AND PURGES ALL THOSE THAT
+; DID NOT MATCH.  EITHER WAY, TBI THEN ADDS THE 'STEP' TO
+; THAT VARIABLE AND CHECK THE RESULT WITH THE LIMIT.  IF IT
+; IS WITHIN THE LIMIT, CONTROL LOOPS BACK TO THE COMMAND
+; FOLLOWING THE 'FOR'.  IF OUTSIDE THE LIMIT, THE SAVE AREA
+; IS PURGED AND EXECUTION CONTINUES.
+;*************************************************************
+
+FOR:
+        CALL PUSHA                      ;SAVE THE OLD SAVE AREA
+        CALL SETVAL                     ;SET THE CONTROL VAR.
+        DEC HL                          ;HL IS ITS ADDRESS
+        LD (LOPVAR),HL                  ;SAVE THAT
+        LD HL,TAB5-1                    ;USE 'EXEC' TO LOOK
+        JP EXEC                         ;FOR THE WORK 'TO'
+FR1:
+        RST 18H                         ;EVALUATE THE LIMITE
+        LD (LOPLMT),HL                  ;SAVE THAT
+        LD HL,TAB6-1                    ;USE 'EXEC' TO LOOK
+        JP EXEC                         ;FOR THE WORD 'STEP'
+FR2:
+        RST 18H                         ;FOUND IT, GET STEP
+        JR FR4
+FR3:
+        LD HL,0001H                     ;NOT FOUND, SET TO 1
+FR4:
+        LD (LOPINC),HL                  ;SAVE THAT TOO
+FR5:
+        LD HL,(CURRNT)                  ;SAVE CURRENT LINE #
+        LD (LOPLN),HL
+        EX DE,HL                        ;AND TEXT POINTER
+        LD (LOPPT),HL
+        LD BC,0AH                       ;DIG INTO STACK TO
+        LD HL,(LOPVAR)                  ;FIND 'LOPVAR'
+        EX DE,HL
+        LD H,B
+        LD L,B                          ;HL=0 NOW
+        ADD HL,SP                       ;HERE IS THE STACK
+        DB 3EH                          ;DISASSEMBLY SAID "ld a,09h"
+FR7:
+        ADD HL,BC                       ;EACH LEVEL IS 10 DEEP - DIS = 09
+        LD A,(HL)                       ;GET THAT OLD 'LOPVAR'
+        INC HL
+        OR (HL)
+        JR Z,FR8                        ;0 SAYS NO MORE IN IT
+        LD A,(HL)
+        DEC HL
+        CP D                            ;SAME AS THIS ONE?
+        JR NZ,FR7
+        LD A,(HL)                       ;THE OTHER HALF?
+        CP E
+        JR NZ,FR7
+        EX DE,HL                        ;YES, FOUND ONE
+        LD HL,0000H
+        ADD HL,SP                       ;TRY TO MOVE SP
+        LD B,H
+        LD C,L
+        LD HL,000AH
+        ADD HL,DE
+        CALL MVDOWN                     ;AND PURGE 10 WORDS
+        LD SP,HL                        ;IN THE STACK
+FR8:
+        LD HL,(LOPPT)                   ;JOB DONE, RESTORE DE
+        EX DE,HL
+        RST 30H                         ;AND CONTINUE
+;
+NEXT:
+        RST 38H                         ;GET ADDRESS OF VAR.
+        JP C,QWHAT                      ;NO VARIABLE, "WHAT?"
+        LD (VARNXT),HL                  ;YES, SAVE IT
+NX0:
+        PUSH DE                         ;SAVE TEXT POINTER
+        EX DE,HL
+        LD HL,(LOPVAR)                  ;GET VAR. IN 'FOR'
+        LD A,H
+        OR L                            ;0 SAYS NEVER HAD ONE
+        JP Z,AWHAT                      ;SO WE ASK: "WHAT?"
+        RST 20H                         ;ELSE WE CHECK THEM
+        JR Z,NX3                        ;OK, THEY AGREE
+        POP DE                          ;NO, LET'S SEE
+        CALL POPA                       ;PURGE CURRENT LOOP
+        LD HL,(VARNXT)                  ;AND POP ONE LEVEL
+        JR NX0                          ;GO CHECK AGAIN
+NX3:
+        LD E,(HL)                       ;COME HERE WHEN AGREED
+        INC HL
+        LD D,(HL)                       ;DE=VALUE OF VAR.
+        LD HL,(LOPINC)
+        PUSH HL
+        LD A,H
+        XOR D
+        LD A,D
+        ADD HL,DE                       ;ADD ONE STEP
+        JP M,NX4
+        XOR H
+        JP M,NX5
+NX4:
+        EX DE,HL
+        LD HL,(LOPVAR)                  ;PUT IT BACK
+        LD (HL),E
+        INC HL
+        LD (HL),D
+        LD HL,(LOPLMT)                  ;HL->LIMIT
+        POP AF                          ;OLD HL
+        OR A
+        JP P,NX1                        ;STEP > 0
+        EX DE,HL                        ;STEP < 0
+NX1:
+        CALL CKHLDE                     ;COMPARE WITH LIMIT
+        POP DE                          ;RESTORE TEXT POINTER
+        JR C,NX2                        ;OUTSIDE LIMIT
+        LD HL,(LOPLN)                   ;WITHIN LIMIT, GO
+        LD (CURRNT),HL                  ;BACK TO THE SAVED
+        LD HL,(LOPPT)                   ;'CURRNT' AND TEXT
+        EX DE,HL                        ;POINTER
+        RST 30H
+NX5:
+        POP HL
+        POP DE
+NX2:
+        CALL POPA                       ;PURGE THIS LOOP
+        RST 30H
+
+;*************************************************************
+;
+; *** REM *** IF *** INPUT *** & LET (& DEFLT) ***
+;
+; 'REM' CAN BE FOLLOWED BY ANYTHING AND IS IGNORED BY TBI.
+; TBI TREATS IT LIKE AN 'IF' WITH A FALSE CONDITION.
+;
+; 'IF' IS FOLLOWED BY AN EXPR. AS A CONDITION AND ONE OR MORE
+; COMMANDS (INCLUDING OTHER 'IF'S) SEPERATED BY SEMI-COLONS.
+; NOTE THAT THE WORD 'THEN' IS NOT USED.  TBI EVALUATES THE
+; EXPR. IF IT IS NON-ZERO, EXECUTION CONTINUES.  IF THE
+; EXPR. IS ZERO, THE COMMANDS THAT FOLLOWS ARE IGNORED AND
+; EXECUTION CONTINUES AT THE NEXT LINE.
+;
+; 'INPUT' COMMAND IS LIKE THE 'PRINT' COMMAND, AND IS FOLLOWED
+; BY A LIST OF ITEMS.  IF THE ITEM IS A STRING IN SINGLE OR
+; DOUBLE QUOTES, OR IS A BACK-ARROW, IT HAS THE SAME EFFECT AS
+; IN 'PRINT'.  IF AN ITEM IS A VARIABLE, THIS VARIABLE NAME IS
+; PRINTED OUT FOLLOWED BY A COLON.  THEN TBI WAITS FOR AN
+; EXPR. TO BE TYPED IN.  THE VARIABLE IS THEN SET TO THE
+; VALUE OF THIS EXPR.  IF THE VARIABLE IS PROCEDED BY A STRING
+; (AGAIN IN SINGLE OR DOUBLE QUOTES), THE STRING WILL BE
+; PRINTED FOLLOWED BY A COLON.  TBI THEN WAITS FOR INPUT EXPR.
+; AND SET THE VARIABLE TO THE VALUE OF THE EXPR.
+;
+; IF THE INPUT EXPR. IS INVALID, TBI WILL PRINT "WHAT?",
+; "HOW?" OR "SORRY" AND REPRINT THE PROMPT AND REDO THE INPUT.
+; THE EXECUTION WILL NOT TERMINATE UNLESS YOU TYPE CONTROL-C.
+; THIS IS HANDLED IN 'INPERR'.
+;
+; 'LET' IS FOLLOWED BY A LIST OF ITEMS SEPERATED BY COMMAS.
+; EACH ITEM CONSISTS OF A VARIABLE, AN EQUAL SIGN, AND AN EXPR.
+; TBI EVALUATES THE EXPR. AND SET THE VARIABLE TO THAT VALUE.
+; TBI WILL ALSO HANDLE 'LET' COMMAND WITHOUT THE WORD 'LET'.
+; THIS IS DONE BY 'DEFLT'.
+;*************************************************************
+
+REM:
+        LD HL,0000H                     ;*** REM ***
+        DB 3EH                          ;THIS IS LIKE 'IF 0'
+IFF:
+        RST 18H                         ;*** IF ***
+        LD A,H                          ;IS THE EXPR.=0?
+        OR L
+        JP NZ,RUNSML                    ;NO, CONTINUE
+        CALL FNDSKP                     ;YES, SKIP REST OF LINE
+        JP NC,RUNTSL                    ;AND RUN THE NEXT LINE
+        JP RSTART                       ;IF NO NEXT, RE-START
+INPERR:
+        LD HL,(STKINP)                  ;*** INPERR ***
+        LD SP,HL                        ;RESTORE OLD SP
+        POP HL                          ;AND OLD 'CURRNT'
+        LD (CURRNT),HL
+        POP DE                          ;AND OLD TEXT POINTER
+        POP DE                          ;REDO INPUT
+INPUT:                                  ;*** INPUT ***
+IP1:
+        PUSH DE                         ;SAVE IN CASE OF ERROR
+        CALL QTSTG                      ;IS NEXT ITEM A STRING?
+        JR IP2                          ;NO
+        RST 38H                         ;YES, BUT FOLLOWED BY A
+        JR C,IP4                        ;VARIABLE? NO.
+        JR IP3                          ;YES. INPUT VARIABLE
+IP2:
+        PUSH DE                         ;SAVE FOR 'PRTSTG'
+        RST 38H                         ;MUST BE VARIABLE NOW
+        JP C,QWHAT                      ;"WHAT?" IT IS NOT?
+        LD A,(DE)                       ;GET READY FOR 'PRTSTR'
+        LD C,A
+        SUB A
+        LD (DE),A
+        POP DE
+        CALL PRTSTG                     ;PRINT STRING AS PROMPT
+        LD A,C                          ;RESTORE TEXT
+        DEC DE
+        LD (DE),A
+IP3:
+        PUSH DE                         ;SAVE TEXT POINTER
+        EX DE,HL
+        LD HL,(CURRNT)                  ;ALSO SAVE 'CURRNT'
+        PUSH HL
+        LD HL,IP1                       ;A NEGATIVE NUMBER
+        LD (CURRNT),HL                  ;AS A FLAG
+        LD HL,0000H                     ;SAVE SP TOO
+        ADD HL,SP
+        LD (STKINP),HL
+        PUSH DE                         ;OLD HL
+        LD A,3AH                        ;PRINT THIS TOO
+        CALL GETLN                      ;AND GET A LINE
+        LD DE,BUFFER                    ;POINTS TO BUFFER
+        RST 18H                         ;EVALUATE INPUT
+        NOP                             ;CAN BE 'CALL ENDCHK'
+        NOP
+        NOP
+        POP DE                          ;OK,GET OLD HL
+        EX DE,HL
+        LD (HL),E                       ;SAVE VALUE IN VAR.
+        INC HL
+        LD (HL),D
+        POP HL                          ;GET OLD 'CURRNT'
+        LD (CURRNT),HL
+        POP DE                          ;AND OLD TEXT POINTER
+IP4:
+        POP AF                          ;PURGE JUNK IN STACK
+        RST 08H                         ;IS NEXT CH. ','?
+        DB ','
+        DB IP5-$-1
+        JR IP1                          ;YES, MORE ITEMS.
+IP5:
+        RST 30H
+DEFLT:
+        LD A,(DE)                       ;***  DEFLT ***
+        CP CR                           ;EMPTY LINE IS OK
+        JR Z,LT1                        ;ELSE IT IS 'LET'
+LET:
+        CALL SETVAL                     ;*** LET ***
+        RST 08H                         ;SET VALUE TO VAR
+        DB ','                          ;---DISASSEMBLE = INC L
+        DB LT1-$-1                      ;---DISASSEMBLE = INC BC
+        JR LET                          ;ITEM BY ITEM
+LT1:
+        RST 30H                         ;UNTIL FINISH
+;*************************************************************
+;
+; *** EXPR ***
+;
+; 'EXPR' EVALUATES ARITHMETICAL OR LOGICAL EXPRESSIONS.
+; <EXPR>::<EXPR2>
+;         <EXPR2><REL.OP.><EXPR2>
+; WHERE <REL.OP.> IS ONE OF THE OPERATORS IN TAB8 AND THE
+; RESULT OF THESE OPERATIONS IS 1 IF TRUE AND 0 IF FALSE.
+; <EXPR2>::=(+ OR -)<EXPR3>(+ OR -<EXPR3>)(....)
+; WHERE () ARE OPTIONAL AND (....) ARE OPTIONAL REPEATS.
+; <EXPR3>::=<EXPR4>(* OR /><EXPR4>)(....)
+; <EXPR4>::=<VARIABLE>
+;           <FUNCTION>
+;           (<EXPR>)
+; <EXPR> IS RECURSIVE SO THAT VARIABLE '@' CAN HAVE AN <EXPR>
+; AS INDEX, FUNCTIONS CAN HAVE AN <EXPR> AS ARGUMENTS, AND
+; <EXPR4> CAN BE AN <EXPR> IN PARANTHESE.
+;*************************************************************
+
+EXPR1:
+        LD HL,TAB8-1                    ;LOOKUP REL.OP.
+        JP EXEC                         ;GO DO IT
+XP11:
+        CALL XP18                       ;REL.OP.">="
+        RET C                           ;NO, RETURN HL=0
+        LD L,A                          ;YES, RETURN HL=1
+        RET
+XP12:
+        CALL XP18                       ;REL.OP."#"
+        RET Z                           ;FALSE, RETURN HL=0
+        LD L,A                          ;TRUE, RETURN HL=1
+        RET
+XP13:
+        CALL XP18                       ;REL.OP.">"
+        RET Z                           ;FALSE
+        RET C                           ;ALSO FALSE, HL=0
+        LD L,A                          ;TRUE, HL=1
+        RET
+XP14:
+        CALL XP18                       ;REL.OP."<="
+        LD L,A                          ;SET HL=1
+        RET Z                           ;REL. TRUE, RETURN
+        RET C
+        LD L,H                          ;ELSE SET HL=0
+        RET
+XP15:
+        CALL XP18                       ;REL.OP."="
+        RET NZ                          ;FALSE, RETURN HL=0
+        LD L,A                          ;ELSE SET HL=1
+        RET
+XP16:
+        CALL XP18                       ;REL.OP."<"
+        RET NC                          ;FALSE, RETURN HL=0
+        LD L,A                          ;ELSE SET HL=1
+        RET
+XP17:
+        POP HL                          ;NOT .REL.OP
+        RET                             ;RETURN HL=<EXPR2>
+XP18:
+        LD A,C                          ;SUBROUTINE FOR ALL
+        POP HL                          ;REL.OP.'S
+        POP BC
+        PUSH HL                         ;REVERSE TOP OF STACK
+        PUSH BC
+        LD C,A
+        CALL EXPR2                      ;GET 2ND <EXPR2>
+        EX DE,HL                        ;VALUE IN DE NOW
+        EX (SP),HL                      ;1ST <EXPR2> IN HL
+        CALL CKHLDE                     ;COMPARE 1ST WITH 2ND
+        POP DE                          ;RESTORE TEXT POINTER
+        LD HL,0000H                     ;SET HL=0, A=1
+        LD A,01H
+        RET
+EXPR2:
+        RST 08H                         ;NEGATIVE SIGN?
+        DB '-'
+        DB XP21-$-1
+        LD HL,0000H                     ;YES, FAKE '0-'
+        JR XP26                         ;TREAT LIKE SUBTRACT
+XP21:
+        RST 08H                         ;POSITIVE SIGN? IGNORE
+        DB '+'
+        DB XP22-$-1
+XP22:
+        CALL EXPR3                      ;1ST <EXPR3>
+XP23:
+        RST 08H                         ;ADD?
+        DB  '+'
+        DB XP25-$-1
+        PUSH HL                         ;YES, SAVE VALUE
+        CALL EXPR3                      ;GET 2ND <EXPR3>
+XP24:
+        EX DE,HL                        ;2ND IN DE
+        EX (SP),HL                      ;1ST IN HL
+        LD A,H                          ;COMPARE SIGN
+        XOR D
+        LD A,D
+        ADD HL,DE
+        POP DE                          ;RESTORE TEXT POINTER
+        JP M,XP23                       ;1ST AND 2ND SIGN DIFFER
+        XOR H                           ;1ST AND 2ND SIGN EQUAL
+        JP P,XP23                       ;SO IS RESULT
+        JP QHOW                         ;ELSE WE HAVE OVERFLOW
+XP25:
+        RST 08H                         ;SUBTRACT?
+        DB '-'
+        DB XP42-$-1
+XP26:
+        PUSH HL                         ;YES, SAVE 1ST <EXPR3>
+        CALL EXPR3                      ;GET 2ND <EXPR3>
+        CALL CHGSGN                     ;NEGATE
+        JR XP24                         ;AND ADD THEM
+;
+EXPR3:
+        CALL EXPR4                      ;GET 1ST <EXPR4>
+XP31:
+        RST 08H                         ;MULTIPLY?
+        DB '*'
+        DB XP34-$-1
+        PUSH HL                         ;YES, SAVE 1ST
+        CALL EXPR4                      ;AND GET 2ND <EXPR4>
+        LD B,00H                        ;CLEAR B FOR SIGN
+        CALL CHKSGN                     ;CHECK SIGN
+        EX (SP),HL                      ;1ST IN HL
+        CALL CHKSGN                     ;CHECK SIGN OF 1ST
+        EX DE,HL
+        EX (SP),HL
+        LD A,H                          ;IS HL > 255 ?
+        OR A
+        JR Z,XP32                       ;NO
+        LD A,D                          ;YES, HOW ABOUT DE
+        OR D
+        EX DE,HL                        ;PUT SMALLER IN HL
+        JP NZ,AHOW                      ;ALSO >, WILL OVERFLOW
+XP32:
+        LD A,L                          ;THIS IS DUMB
+        LD HL,0000H                     ;CLEAR RESULT
+        OR A                            ;ADD AND COUNT
+        JR Z,XP35
+XP33:
+        ADD HL,DE
+        JP C,AHOW                       ;OVERFLOW
+        DEC A
+        JR NZ,XP33
+        JR XP35                         ;FINISHED
+XP34:
+        RST 08H                         ;DIVIDE?
+        DB '/'
+        DB XP42-$-1
+        PUSH HL                         ;YES, SAVE 1ST <EXPR4>
+        CALL EXPR4                      ;AND GET THE SECOND ONE
+        LD B,00H                        ;CLEAR B FOR SIGN
+        CALL CHKSGN                     ;CHECK SIGN OF 2ND
+        EX (SP),HL                      ;GET 1ST IN HL
+        CALL CHKSGN                     ;CHECK SIGN OF 1ST
+        EX DE,HL
+        EX (SP),HL
+        EX DE,HL
+        LD A,D                          ;DIVIDE BY 0?
+        OR E
+        JP Z,AHOW                       ;SAY "HOW?"
+        PUSH BC                         ;ELSE SAVE SIGN
+        CALL DIVIDE                     ;USE SUBROUTINE
+        LD H,B                          ;RESULT IN HL NOW
+        LD L,C
+        POP BC                          ;GET SIGN BACK
+XP35:
+        POP DE                          ;AND TEXT POINTER
+        LD A,H                          ;HL MUST BE +
+        OR A
+        JP M,QHOW                       ;ELSE IT IS OVERFLOW
+        LD A,B
+        OR A
+        CALL M,CHGSGN                   ;CHANGE SIGN IF NEEDED
+        JR XP31                         ;LOOK FOR MORE TERMS
+EXPR4:
+        LD HL,TAB4-1                    ;FIND FUNCTION IN TAB4
+        JP EXEC                         ;AND GO DO IT
+XP40:
+        RST 38H                         ;NO, NOT A FUNCTION
+        JR C,XP41                       ;NOR A VARIABLE
+        LD A,(HL)                       ;VARIABLE
+        INC HL
+        LD H,(HL)                       ;VALUE IN HL
+        LD L,A
+        RET
+XP41:
+        CALL TSTNUM                     ;OR IS IT A NUMBER
+        LD A,B                          ;# OF DIGIT
+        OR A
+        RET NZ                          ;OK
+PARN:
+        RST 08H
+        DB '('
+        DB XP43-$-1
+        RST 18H                         ;"(EXPR)"
+        RST 08H
+        DB ')'
+        DB XP43-$-1
+XP42:
+        RET
+XP43:
+        JP QWHAT                        ;ELSE SAY: "WHAT?"
+RND:
+        CALL PARN                       ;*** RND(EXPR) ***
+        LD A,H                          ;EXPR MUST BE +
+        OR A
+        JP M,QHOW
+        OR L                            ;AND NON-ZERO
+        JP Z,QHOW
+        PUSH DE                         ;SAVE BOTH
+        PUSH HL
+        LD HL,(RANPNT)                  ;GET MEMORY AS RANDOM
+        LD DE,LSTROM                    ;NUMBER
+        RST 20H
+        JR C,RA1                        ;WRAP AROUND IF LAST
+        LD HL,START
+RA1:
+        LD E,(HL)
+        INC HL
+        LD D,(HL)
+        LD (RANPNT),HL
+        POP HL
+        EX DE,HL
+        PUSH BC
+        CALL DIVIDE                     ;RND (N)=MOD(M,N)+1
+        POP BC
+        POP DE
+        INC HL
+        RET
+ABS:
+        CALL PARN                       ;*** ABS (EXPR) ***
+        DEC DE
+        CALL CHKSGN                     ;CHECK SIGN
+        INC DE
+        RET
+SIZE:
+        LD HL,(TXTUNF)                  ;*** SIZE ***
+        PUSH DE                         ;GET THE NUMBER OF FREE
+        EX DE,HL                        ;BYTES BETWEEN 'TXTUNF'
+        LD HL,VARBGN                    ;AND 'VARBGN'
+        CALL SUBDE
+        POP DE
+        RET
+;*************************************************************
+;
+; *** DIVIDE *** SUBDE *** CHKSGN *** CHGSGN *** & CKHLDE ***
+;
+; 'DIVIDE' DIVIDES HL BY DE, RESULT IN BC, REMAINDER IN HL
+;
+; 'SUBDE' SUBSTRACTS DE FROM HL
+;
+; 'CHKSGN' CHECKS SIGN OF HL.  IF +, NO CHANGE.  IF -, CHANGE
+; SIGN AND FLIP SIGN OF B.
+;
+; 'CHGSGN' CHECKS SIGN N OF HL AND B UNCONDITIONALLY.
+;
+; 'CKHLDE' CHECKS SIGN OF HL AND DE.  IF DIFFERENT, HL AND DE
+; ARE INTERCHANGED.  IF SAME SIGN, NOT INTERCHANGED.  EITHER
+; CASE, HL DE ARE THEN COMPARED TO SET THE FLAGS.
+;*************************************************************
+
+DIVIDE:
+        PUSH HL                         ;*** DIVIDE ***
+        LD L,H                          ;DIVIDE H BY DE
+        LD H,00H
+        CALL DV1
+        LD B,C                          ;SAVE RESULT IN B
+        LD A,L                          ;(REMAINDER+L)/DE
+        POP HL
+        LD H,A
+DV1:
+        LD C,0FFH                       ;RESULT IN C
+DV2:
+        INC C                           ;DUMB ROUTINE
+        CALL SUBDE                      ;DIVIDE BY SUBTRACT
+        JR NC,DV2                       ;AND COUNT
+        ADD HL,DE
+        RET
+SUBDE:
+        LD A,L                          ;*** SUBDE ***
+        SUB E                           ;SUBSTRACT DE FROM
+        LD L,A                          ;HL
+        LD A,H
+        SBC A,D
+        LD H,A
+        RET
+CHKSGN:
+        LD A,H                          ;*** CHKSGN ***
+        OR A                            ;CHECK SIGN OF HL
+        RET P
+CHGSGN:
+        LD A,H                          ;*** CHGSGN ***
+        PUSH AF
+        CPL                             ;CHANGE SIGN OF HL
+        LD H,A
+        LD A,L
+        CPL
+        LD L,A
+        INC HL
+        POP AF
+        XOR H
+        JP P,QHOW
+        LD A,B                          ;AND ALSO FLIP B
+        XOR 80H
+        LD B,A
+        RET
+CKHLDE:
+        LD A,H                          ;SAME SIGN?
+        XOR D                           ;YES, COMPARE
+        JP P,CK1                        ;NO, XCHANGE AND COMP
+        EX DE,HL
+CK1:
+        RST 20H
+        RET
+;*************************************************************
+;
+; *** SETVAL *** FIN *** ENDCHK *** & ERROR (& FRIENDS) ***
+;
+; "SETVAL" EXPECTS A VARIABLE, FOLLOWED BY AN EQUAL SIGN AND
+; THEN AN EXPR.  IT EVALUATES THE EXPR. AND SET THE VARIABLE
+; TO THAT VALUE.
+;
+; "FIN" CHECKS THE END OF A COMMAND.  IF IT ENDED WITH ";",
+; EXECUTION CONTINUES.  IF IT ENDED WITH A CR, IT FINDS THE
+; NEXT LINE AND CONTINUE FROM THERE.
+;
+; "ENDCHK" CHECKS IF A COMMAND IS ENDED WITH CR.  THIS IS
+; REQUIRED IN CERTAIN COMMANDS.  (GOTO, RETURN, AND STOP ETC.)
+;
+; "ERROR" PRINTS THE STRING POINTED BY DE (AND ENDS WITH CR).
+; IT THEN PRINTS THE LINE POINTED BY 'CURRNT' WITH A "?"
+; INSERTED AT WHERE THE OLD TEXT POINTER (SHOULD BE ON TOP
+; OF THE STACK) POINTS TO.  EXECUTION OF TB IS STOPPED
+; AND TBI IS RESTARTED.  HOWEVER, IF 'CURRNT' -> ZERO
+; (INDICATING A DIRECT COMMAND), THE DIRECT COMMAND IS NOT
+; PRINTED.  AND IF 'CURRNT' -> NEGATIVE # (INDICATING 'INPUT'
+; COMMAND), THE INPUT LINE IS NOT PRINTED AND EXECUTION IS
+; NOT TERMINATED BUT CONTINUED AT 'INPERR'.
+;
+; RELATED TO 'ERROR' ARE THE FOLLOWING:
+; 'QWHAT' SAVES TEXT POINTER IN STACK AND GET MESSAGE "WHAT?"
+; 'AWHAT' JUST GET MESSAGE "WHAT?" AND JUMP TO 'ERROR'.
+; 'QSORRY' AND 'ASORRY' DO SAME KIND OF THING.
+; 'AHOW' AND 'AHOW' IN THE ZERO PAGE SECTION ALSO DO THIS.
+;*************************************************************
+
+SETVAL:
+        RST 38H                         ;*** SETVAL ***
+        JP C,QWHAT                      ;"WHAT?" NO VARIABLE
+        PUSH HL                         ;SAVE ADDRESS OF VAR.
+        RST 08H                         ;PASS "=" SIGN
+        DB '='
+        DB SV1-$-1
+        RST 18H                         ;EVALUATE EXPR.
+        LD B,H                          ;VALUE IS IN BC NOW
+        LD C,L
+        POP HL                          ;GET ADDRESS
+        LD (HL),C                       ;SAVE VALUE
+        INC HL
+        LD (HL),B
+        RET
+SV1:
+        JP QWHAT                        ;NO "=" SIGN
+FIN:
+        RST 08H                         ;*** FIN ***
+        DB 3BH
+        DB FI1-$-1
+        POP AF                          ;";", PURGE RET. ADDR.
+        JP RUNSML                       ;CONTINUE SAME LINE
+FI1:
+        RST 08H                         ;NOT ";", IS IT CR?
+        DB CR
+        DB FI2-$-1
+        POP AF                          ;YES, PURGE RET. ADDR.
+        JP RUNNXL                       ;RUN NEXT LINE
+FI2:
+        RET                             ;ELSE RETURN TO CALLER
+ENDCHK:
+        RST 28H                         ;*** ENDCHK ***
+        CP CR                           ;END WITH CR?
+        RET Z                           ;OK, ELSE SAY: "WHAT?"
+QWHAT:
+        PUSH DE                         ;*** QWHAT ***
+AWHAT:
+        LD DE,WHAT                      ;*** AWHAT ***
+ERROR_ROUTINE:
+        SUB A                           ;*** ERROR ***
+        CALL PRTSTG                     ;PRINT 'WHAT?', 'HOW?'
+        POP DE                          ;OR 'SORRY'
+        LD A,(DE)                       ;SAVE THE CHARACTER
+        PUSH AF                         ;AT WHERE OLD DE ->
+        SUB A                           ;AND PUT A 0 THERE
+        LD (DE),A
+        LD HL,(CURRNT)                  ;GET CURRENT LINE #
+        PUSH HL
+        LD A,(HL)                       ;CHECK THE VALUE
+        INC HL
+        OR (HL)
+        POP DE
+        JP Z,RSTART                     ;IF ZERO, JUST RESTART
+        LD A,(HL)                       ;IF NEGATIVE,
+        OR A
+        JP M,INPERR                     ;REDO INPUT
+        CALL PRTLN                      ;ELSE PRINT THE LINE
+        DEC DE                          ;UPTO WHERE THE 0 IS
+        POP AF                          ;RESTORE THE CHARACTER
+        LD (DE),A
+        LD A,3FH                        ;PRINT A "?"
+        RST 10H
+        SUB A                           ;AND THE REST OF THE
+        CALL PRTSTG                     ;LINE
+        JP RSTART                       ;THEN RESTART
+QSORRY:
+        PUSH DE                         ;*** QSORRY ***
+ASORRY:
+        LD DE,SORRY                     ;*** ASORRY ***
+        JR ERROR_ROUTINE
+;*************************************************************
+;
+; *** GETLN *** FNDLN (& FRIENDS) ***
+;
+; 'GETLN' READS A INPUT LINE INTO 'BUFFER'.  IT FIRST PROMPT
+; THE CHARACTER IN A (GIVEN BY THE CALLER), THEN IT FILLS
+; THE BUFFER AND ECHOS.  IT IGNORES LF'S AND NULLS, BUT STILL
+; ECHOS THEM BACK.  RUB-OUT IS USED TO CAUSE IT TO DELETE
+; THE LAST CHARACTER (IF THERE IS ONE), AND ALT-MOD IS USED TO
+; CAUSE IT TO DELETE THE WHOLE LINE AND START IT ALL OVER.
+; CR SIGNALS THE END OF A LINE, AND CAUSE 'GETLN' TO RETURN.
+;
+; 'FNDLN' FINDS A LINE WITH A GIVEN LINE # (IN HL) IN THE
+; TEXT SAVE AREA.  DE IS USED AS THE TEXT POINTER.  IF THE
+; LINE IS FOUND, DE WILL POINT TO THE BEGINNING OF THAT LINE
+; (I.E., THE LOW BYTE OF THE LINE #), AND FLAGS ARE NC & Z.
+; IF THAT LINE IS NOT THERE AND A LINE WITH A HIGHER LINE #
+; IS FOUND, DE POINTS TO THERE AND FLAGS ARE NC & NZ.  IF
+; WE REACHED THE END OF TEXT SAVE AREA AND CANNOT FIND THE
+; LINE, FLAGS ARE C & NZ.
+; 'FNDLN' WILL INITIALIZE DE TO THE BEGINNING OF THE TEXT SAVE
+; AREA TO START THE SEARCH.  SOME OTHER ENTRIES OF THIS
+; ROUTINE WILL NOT INITIALIZE DE AND DO THE SEARCH.
+; 'FNDLNP' WILL START WITH DE AND SEARCH FOR THE LINE #.
+; 'FNDNXT' WILL BUMP DE BY 2, FIND A CR AND THEN START SEARCH.
+; 'FNDSKP' USE DE TO FIND A CR, AND THEN START SEARCH.
+;*************************************************************
+
+GETLN:
+        RST 10H                         ;*** GETLN ***
+        LD DE,BUFFER                    ;PROMPT AND INIT.
+GL1:
+        CALL CHKIO                      ;CHECK KEYBOARD
+        JR Z,GL1                        ;NO INPUT, WAIT
+        CP 7FH                          ;DELETE LAST CHARACTER?
+        JR Z,GL3                        ;YES
+        RST 10H                         ;INPUT, ECHO BACK
+        CP 0AH                          ;IGNORE LF
+        JR Z,GL1
+        OR A                            ;IGNORE NULL
+        JR Z,GL1
+        CP 7DH                          ;DELETE THE WHOLE LINE?
+        JR Z,GL4                        ;YES
+        LD (DE),A                       ;ELSE SAVE INPUT
+        INC DE                          ;AND BUMP POINTER
+        CP 0DH                          ;WAS IT CR
+        RET Z                           ;YES, END OF LINE
+        LD A,E                          ;ELSE MORE FREE ROOM?
+        CP BUFEND & 0FFH
+        JR NZ,GL1                       ;YES, GET NEXT INPUT
+GL3:
+        LD A,E                          ;DELETE LAST CHARACTER
+        CP BUFFER & 0FFH                ;BUT DO WE HAVE ANY?
+        JR Z,GL4                        ;NO, REDO WHOLE LINE
+        DEC DE                          ;YES, BACKUP POINTER
+        LD A,5CH                        ;AND ECHO A BACK-SLASH
+        RST 10H
+        JR GL1                          ;GO GET NEXT INPUT
+GL4:
+        CALL CRLF                       ;REDO ENTIRE LINE
+        LD A,05EH                       ;CR, LF AND UP-ARROW
+        JR GETLN
+FNDLN:
+        LD A,H                          ;*** FNDLN ***
+        OR A                            ;CHECK SIGN OF HL
+        JP M,QHOW                       ;IT CANNOT BE -
+        LD DE,TXTBGN                    ;INIT TEXT POINTER
+FNDLP:                                  ;*** FDLNP ***
+FL1:
+        PUSH HL                         ;SAVE LINE #
+        LD HL,(TXTUNF)                  ;CHECK IF WE PASSED END
+        DEC HL
+        RST 20H
+        POP HL                          ;GET LINE # BACK
+        RET C                           ;C,NZ PASSED END
+        LD A,(DE)                       ;WE DID NOT, GET BYTE 1
+        SUB L                           ;IS THIS THE LINE?
+        LD B,A                          ;COMPARE LOW ORDER
+        INC DE
+        LD A,(DE)                       ;GET BYTE 2
+        SBC A,H                         ;COMPARE HIGH ORDER
+        JR C,FL2                        ;NO, NOT THERE YET
+        DEC DE                          ;ELSE WE EITHER FOUND
+        OR B                            ;IT, OR IT IS NOT THERE
+        RET                             ;NC,Z;FOUND, NC,NZ:NO
+FNDNXT:                                 ;*** FNDNXT ***
+        INC DE                          ;FIND NEXT LINE
+FL2:
+        INC DE                          ;JUST PASSED BYTE 1 & 2
+FNDSKP:
+        LD A,(DE)                       ;*** FNDSKP ***
+        CP CR                           ;TRY TO FIND CR
+        JR NZ,FL2                       ;KEEP LOOKING
+        INC DE                          ;FOUND CR, SKIP OVER
+        JR FL1                          ;CHECK IF END OF TEXT
+;*************************************************************
+;
+; *** PRTSTG *** QTSTG *** PRTNUM *** & PRTLN ***
+;
+; 'PRTSTG' PRINTS A STRING POINTED BY DE.  IT STOPS PRINTING
+; AND RETURNS TO CALLER WHEN EITHER A CR IS PRINTED OR WHEN
+; THE NEXT BYTE IS THE SAME AS WHAT WAS IN A (GIVEN BY THE
+; CALLER).  OLD A IS STORED IN B, OLD B IS LOST.
+;
+; 'QTSTG' LOOKS FOR A BACK-ARROW, SINGLE QUOTE, OR DOUBLE
+; QUOTE.  IF NONE OF THESE, RETURN TO CALLER.  IF BACK-ARROW,
+; OUTPUT A CR WITHOUT A LF.  IF SINGLE OR DOUBLE QUOTE, PRINT
+; THE STRING IN THE QUOTE AND DEMANDS A MATCHING UNQUOTE.
+; AFTER THE PRINTING THE NEXT 3 BYTES OF THE CALLER IS SKIPPED
+; OVER (USUALLY A JUMP INSTRUCTION.
+;
+; 'PRTNUM' PRINTS THE NUMBER IN HL.  LEADING BLANKS ARE ADDED
+; IF NEEDED TO PAD THE NUMBER OF SPACES TO THE NUMBER IN C.
+; HOWEVER, IF THE NUMBER OF DIGITS IS LARGER THAN THE # IN
+; C, ALL DIGITS ARE PRINTED ANYWAY.  NEGATIVE SIGN IS ALSO
+; PRINTED AND COUNTED IN, POSITIVE SIGN IS NOT.
+;
+; 'PRTLN' PRINTS A SAVED TEXT LINE WITH LINE # AND ALL.
+;*************************************************************
+
+PRTSTG:
+        LD B,A                          ;*** PRTSTG ***
+PS1:
+        LD A,(DE)                       ;GET A CHARACTER
+        INC DE                          ;BUMP POINTER
+        CP B                            ;SAME AS OLD A?
+        RET Z                           ;YES, RETURN
+        RST 10H                         ;NO, NEXT
+        CP CR                           ;WAS IT A CR?
+        JR NZ,PS1                       ;NO, NEXT
+        RET                             ;YES, RETURN
+QTSTG:
+        RST 08H                         ;*** QTSTG ***
+        DB '"'
+        DB QT3-$-1
+        LD A,22H                        ;IT IS A "
+QT1:
+        CALL PRTSTG                     ;PRINT UNTIL ANOTHER
+        CP CR                           ;WAS LAST ONE A CR?
+        POP HL                          ;RETURN ADDRESS
+        JP Z,RUNNXL                     ;WAS CR, RUN NEXT LINE
+QT2:
+        INC HL                          ;SKIP 3 BYTES ON RETURN
+        INC HL
+        INC HL
+        JP (HL)                         ;RETURN
+QT3:
+        RST 08H                         ;IS IT A '?
+        DB 27H
+        DB QT4-$-1
+        LD A,27H                        ;YES, DO THE SAME
+        JR QT1                          ;AS IN "
+QT4:
+        RST 08H                         ;IS IT BACK-ARROW?
+        DB 5FH
+        DB QT5-$-1
+        LD A,8DH                        ;YES, CR WITHOUT LF
+        RST 10H                         ;DO IT TWICE TO GIVE
+        RST 10H                         ;TTY ENOUGH TIME
+        POP HL                          ;RETURN ADDRESS
+        JR QT2
+QT5:
+        RET                             ;NONE OF ABOVE
+;
+PRTNUM:
+        LD B,00H                        ;*** PRTNUM ***
+        CALL CHKSGN                     ;CHECK SIGN
+        JP P,PN1                        ;NO SIGN
+        LD B,'-'                        ;B=SIGN
+        DEC C                           ;'-' TAKES SPACE
+PN1:
+        PUSH DE                         ;SAVE
+        LD DE,000AH                     ;DECIMAL
+        PUSH DE                         ;SAVE AS FLAG
+        DEC C                           ;C=SPACES
+        PUSH BC                         ;SAVE SIGN & SPACE
+PN2:
+        CALL DIVIDE                     ;DIVIDE HL BY 10
+        LD A,B                          ;RESULT 0?
+        OR C
+        JR Z,PN3                        ;YES, WE GOT ALL
+        EX (SP),HL                      ;NO, SAVE REMAINDER
+        DEC L                           ;AND COUNT SPACE
+        PUSH HL                         ;HL IS OLD BC
+        LD H,B                          ;MOVE RESULT TO BC
+        LD L,C
+        JR PN2                          ;AND DIVIDE BY 10
+PN3:
+        POP BC                          ;WE GOT ALL DIGITS IN
+PN4:
+        DEC C                           ;THE STACK
+        LD A,C                          ;LOOK AT SPACE COUNT
+        OR A
+        JP M,PN5                        ;NO LEADING BLANKS
+        LD A,20H                        ;LEADING BLANKS
+        RST 10H
+        JR PN4                          ;MORE?
+PN5:
+        LD A,B                          ;PRINT SIGN
+        OR A
+        CALL NZ,0010H
+        LD E,L                          ;LAST REMAINDER IN E
+PN6:
+        LD A,E                          ;CHECK DIGIT IN E
+        CP 0AH                          ;10 IS FLAG FOR NO MORE
+        POP DE
+        RET Z                           ;IF SO, RETURN
+        ADD A,30H                       ;ELSE, CONVERT TO ASCII
+        RST 10H                         ;PRINT THE DIGIT
+        JR PN6                          ;GO BACK FOR MORE
+PRTLN:
+        LD A,(DE)                       ;*** PRTLN ***
+        LD L,A                          ;LOW ORDER LINE #
+        INC DE
+        LD A,(DE)                       ;HIGH ORDER
+        LD H,A
+        INC DE
+        LD C,04H                        ;PRINT 4 DIGIT LINE #
+        CALL PRTNUM
+        LD A,20H                        ;FOLLOWED BY A BLANK
+        RST 10H
+        SUB A                           ;AND THEN THE NEXT
+        CALL PRTSTG
+        RET
+;*************************************************************
+;
+; *** MVUP *** MVDOWN *** POPA *** & PUSHA ***
+;
+; 'MVUP' MOVES A BLOCK UP FROM WHERE DE-> TO WHERE BC-> UNTIL
+; DE = HL
+;
+; 'MVDOWN' MOVES A BLOCK DOWN FROM WHERE DE-> TO WHERE HL->
+; UNTIL DE = BC
+;
+; 'POPA' RESTORES THE 'FOR' LOOP VARIABLE SAVE AREA FROM THE
+; STACK
+;
+; 'PUSHA' STACKS THE 'FOR' LOOP VARIABLE SAVE AREA INTO THE
+; STACK
+;*************************************************************
+
+MVUP:
+        RST 20H                         ;*** MVUP ***
+        RET Z                           ;DE = HL, RETURN
+        LD A,(DE)                       ;GET ONE BYTE
+        LD (BC),A                       ;MOVE IT
+        INC DE                          ;INCREASE BOTH POINTERS
+        INC BC
+        JR MVUP                         ;UNTIL DONE
+MVDOWN:
+        LD A,B                          ;*** MVDOWN ***
+        SUB D                           ;TEST IF DE = BC
+        JP NZ,MD1                       ;NO, GO MOVE
+        LD A,C                          ;MAYBE, OTHER BYTE?
+        SUB E
+        RET Z                           ;YES, RETURN
+MD1:
+        DEC DE                          ;ELSE MOVE A BYTE
+        DEC HL                          ;BUT FIRST DECREASE
+        LD A,(DE)                       ;BOTH POINTERS AND
+        LD (HL),A                       ;THEN DO IT
+        JR MVDOWN                       ;LOOP BACK
+POPA:
+        POP BC                          ;BC = RETURN ADDR.
+        POP HL                          ;RESTORE LOPVAR, BUT
+        LD (LOPVAR),HL                  ;=0 MEANS NO MORE
+        LD A,H
+        OR L
+        JR Z,PP1                        ;YEP, GO RETURN
+        POP HL                          ;NOP, RESTORE OTHERS
+        LD (LOPINC),HL
+        POP HL
+        LD (LOPLMT),HL
+        POP HL
+        LD (LOPLN),HL
+        POP HL
+        LD (LOPPT),HL
+PP1:
+        PUSH BC                         ;BC = RETURN ADDR.
+        RET
+PUSHA:
+        LD HL,STKLMT                    ;*** PUSHA ***
+        CALL CHGSGN
+        POP BC                          ;BC=RETURN ADDRESS
+        ADD HL,SP                       ;IS STACK NEAR THE TOP?
+        JP NC,QSORRY                    ;YES, SORRY FOR THAT
+        LD HL,(LOPVAR)                  ;ELSE SAVE LOOP VAR'S
+        LD A,H                          ;BUT IF LOPVAR IS 0
+        OR L                            ;THAT WILL BE ALL
+        JR Z,PU1
+        LD HL,(LOPPT)                   ;ELSE, MORE TO SAVE
+        PUSH HL
+        LD HL,(LOPLN)
+        PUSH HL
+        LD HL,(LOPLMT)
+        PUSH HL
+        LD HL,(LOPINC)
+        PUSH HL
+        LD HL,(LOPVAR)
+PU1:
+        PUSH HL
+        PUSH BC                         ;BC = RETURN ADDR.
+        RET
+;*************************************************************
+;
+; *** OUTC *** & CHKIO ***
+;
+; THESE ARE THE ONLY I/O ROUTINES IN TBI.
+; 'OUTC' IS CONTROLLED BY A SOFTWARE SWITCH 'OCSW'.  IF OCSW=0
+; 'OUTC' WILL JUST RETURN TO THE CALLER.  IF OCSW IS NOT 0,
+; IT WILL OUTPUT THE BYTE IN A.  IF THAT IS A CR, A LF IS ALSO
+; SEND OUT.  ONLY THE FLAGS MAY BE CHANGED AT RETURN. ALL REG.
+; ARE RESTORED.
+;
+; 'CHKIO' CHECKS THE INPUT.  IF NO INPUT, IT WILL RETURN TO
+; THE CALLER WITH THE Z FLAG SET.  IF THERE IS INPUT, Z FLAG
+; IS CLEARED AND THE INPUT BYTE IS IN A.  HOWEVER, IF THE
+; INPUT IS A CONTROL-O, THE 'OCSW' SWITCH IS COMPLIMENTED, AND
+; Z FLAG IS RETURNED.  IF A CONTROL-C IS READ, 'CHKIO' WILL
+; RESTART TBI AND DO NOT RETURN TO THE CALLER.
+;
+; Do not modify these routines.  Routines requiring
+; modification are : SERIAL_INIT, RX_RDY, and TX_RDY.
+;*************************************************************
+
+INIT:
+        CALL SERIAL_INIT        ;INITIALIZE THE SIO
+        LD D,19H
+PATLOP:
+        CALL CRLF
+        DEC D
+        JR NZ,PATLOP
+        SUB A
+        LD DE,MSG1          ;PRINT THE BOOT MESSAGES
+        CALL PRTSTG
+        LD DE,MSG2
+        CALL PRTSTG
+        LD HL,START
+        LD (RANPNT),HL
+        LD HL,TXTBGN
+        LD (TXTUNF),HL
+        JP RSTART
+OUTC:
+        JR NZ,OUTC2         ;IT IS ON
+        POP AF                          ;IT IS OFF
+        RET                             ;RESTORE AF AND RETURN
+OUTC2:
+        CALL TX_RDY         ;SEE IF TRANSMIT IS AVAILABLE
+        POP AF                          ;RESTORE THE REGISTER
+        OUT (SerialPort),A      ;SEND THE BYTE
+        CP CR
+        RET NZ
+        LD A,LF
+        RST 10H
+        LD A,CR
+        RET
+CHKIO:
+        CALL RX_RDY         ;CHECK IF CHARACTER AVAILABLE
+        RET Z                           ;RETURN IF NO CHARACTER AVAILABLE
+
+        PUSH BC                         ;IF IT'S A LF, IGNORE AND RETURN
+        LD B,A                          ; AS IF THERE WAS NO CHARACTER.
+        SUB LF
+        JR Z,CHKIO2
+        LD A,B                          ;OTHERWISE RESTORE 'A' AND 'BC'
+        POP BC                          ; AND CONTINUE ON.
+
+        CP 0FH                          ;IS IT CONTROL-0?
+        JR NZ,CI1                       ;NO, MORE CHECKING
+        LD A,(OCSW)                     ;CONTROL-0 FLIPS OCSW
+        CPL                             ;ON TO OFF, OFF TO ON
+        LD (OCSW),A
+        JR CHKIO                        ;GET ANOTHER INPUT
+CHKIO2:
+        LD A,00H                        ;CLEAR A
+        OR A                            ;ZET THE Z-FLAG
+        POP BC                          ;RESTORE THE 'BC' PAIR
+        RET                             ;RETURN WITH 'Z' SET.
+CI1:
+        CP 03H                          ;IS IT CONTROL-C?
+        RET NZ                          ;NO, RETURN "NZ"
+        JP RSTART                       ;YES, RESTART TBI
+
+
+MSG1:   DB   ESC,"[2J",ESC,"[H"         ;SCREEN CLEAR
+        DB   'Z80 TINY BASIC 2.0g',CR       ;BOOT MESSAGE
+MSG2:   DB   'PORTED BY DOUG GABBARD, 2017',CR
+
+;*************************************************************
+;
+; *** TABLES *** DIRECT *** & EXEC ***
+;
+; THIS SECTION OF THE CODE TESTS A STRING AGAINST A TABLE.
+; WHEN A MATCH IS FOUND, CONTROL IS TRANSFERED TO THE SECTION
+; OF CODE ACCORDING TO THE TABLE.
+;
+; AT 'EXEC', DE SHOULD POINT TO THE STRING AND HL SHOULD POINT
+; TO THE TABLE-1.  AT 'DIRECT', DE SHOULD POINT TO THE STRING.
+; HL WILL BE SET UP TO POINT TO TAB1-1, WHICH IS THE TABLE OF
+; ALL DIRECT AND STATEMENT COMMANDS.
+;
+; A '.' IN THE STRING WILL TERMINATE THE TEST AND THE PARTIAL
+; MATCH WILL BE CONSIDERED AS A MATCH.  E.G., 'P.', 'PR.',
+; 'PRI.', 'PRIN.', OR 'PRINT' WILL ALL MATCH 'PRINT'.
+;
+; THE TABLE CONSISTS OF ANY NUMBER OF ITEMS.  EACH ITEM
+; IS A STRING OF CHARACTERS WITH BIT 7 SET TO 0 AND
+; A JUMP ADDRESS STORED HI-LOW WITH BIT 7 OF THE HIGH
+; BYTE SET TO 1.
+;
+; END OF TABLE IS AN ITEM WITH A JUMP ADDRESS ONLY.  IF THE
+; STRING DOES NOT MATCH ANY OF THE OTHER ITEMS, IT WILL
+; MATCH THIS NULL ITEM AS DEFAULT.
+;*************************************************************
+
+TAB1:                                   ;DIRECT COMMANDS
+        DB 'LIST'
+        DWA LIST
+        DB 'RUN'
+        DWA RUN
+        DB 'NEW'
+        DWA NEW
+TAB2:                                   ;DIRECT/STATEMENT
+        DB 'NEXT'
+        DWA NEXT
+        DB 'LET'
+        DWA LET
+        DB 'IF'
+        DWA IFF
+        DB 'GOTO'
+        DWA GOTO
+        DB 'GOSUB'
+        DWA GOSUB
+        DB 'RETURN'
+        DWA RETURN
+        DB 'REM'
+        DWA REM
+        DB 'FOR'
+        DWA FOR
+        DB 'INPUT'
+        DWA INPUT
+        DB 'PRINT'
+        DWA PRINT
+        DB 'STOP'
+        DWA STOP
+        DWA DEFLT
+TAB4:                                   ;FUNCTIONS
+        DB 'RND'
+        DWA RND
+        DB 'ABS'
+        DWA ABS
+        DB 'SIZE'
+        DWA SIZE
+        DWA XP40
+TAB5:                                   ;"TO" IN "FOR"
+        DB 'TO'
+        DWA FR1
+        DWA QWHAT
+TAB6:                                   ;"STEP" IN "FOR"
+        DB 'STEP'
+        DWA FR2
+        DWA FR3
+TAB8:                                   ;RELATION OPERATORS
+        DB '>='
+        DWA XP11
+        DB '#'
+        DWA XP12
+        DB '>'
+        DWA XP13
+        DB '='
+        DWA XP15
+        DB '<='
+        DWA XP14
+        DB '<'
+        DWA XP16
+        DWA XP17
+DIRECT: LD HL,TAB1-1                   ;*** DIRECT ***
+EXEC:                                   ;*** EXEC ***
+EX0:    RST 28H                         ;IGNORE LEADING BLANKS
+        PUSH DE                         ;SAVE POINTER
+EX1:
+        LD A,(DE)                       ;IF FOUND '.' IN STRING
+        INC DE                          ;BEFORE ANY MISMATCH
+        CP 23H                          ;WE DECLARE A MATCH
+        JR Z,EX3
+        INC HL                          ;HL->TABLE
+        CP (HL)                         ;IF MATCH, TEST NEXT
+        JR Z,EX1
+        LD A,7FH                        ;ELSE SEE IF BIT 7
+        DEC DE                          ;OF TABLE IS SET, WHICH
+        CP (HL)                         ;IS THE JUMP ADDR. (HI)
+        JR C,EX5                        ;C:YES, MATCHED
+EX2:
+        INC HL                          ;NC:NO, FIND JUMP ADDR.
+        CP (HL)
+        JR NC,EX2
+        INC HL                          ;BUMP TO NEXT TAB. ITEM
+        POP DE                          ;RESTORE STRING POINTER
+        JR EX0                          ;TEST AGAINST NEXT ITEM
+EX3:
+        LD A,7FH                        ;PARTIAL MATCH, FIND
+EX4:
+        INC HL                          ;JUMP ADDR., WHICH IS
+        CP (HL)                         ;FLAGGED BY BIT 7
+        JR NC,EX4
+EX5:
+        LD A,(HL)                       ;LOAD HL WITH THE JUMP
+        INC HL                          ;ADDRESS FROM THE TABLE
+        LD L,(HL)
+        AND 7FH                         ;MASK OFF BIT 7
+        LD H,A
+        POP AF                          ;CLEAN UP THE GABAGE
+        JP (HL)                         ;AND WE GO DO IT
+;-------------------------------------------------------------------------------
+;///////////////////////////////////////////////////////////////////////////////
+;-------------------------------------------------------------------------------
+;COMPUTER SPECIFIC ROUTINES.
+;-------------------------------------------------------------------------------
+SERIAL_INIT:
+
+    ; This routine is for initializing your serial port.
+
+        RET
+;-------------------------------------------------------------------------------
+TX_RDY:
+
+    ; This routine is checking if the Serial Port is ready to send
+    ; a character.
+    
+    RET
+        
+;-------------------------------------------------------------------------------
+RX_RDY:
+
+    ; This routine is for checkif if a character is available over
+    ; serial. If a character is available, it returns to the calling
+    ; function with the character in 'A' and the Z-flag reset.
+    ; However, if a character is not available, it returns with the
+    ; Z-flag set.
+
+        RET
+;-------------------------------------------------------------------------------
+;///////////////////////////////////////////////////////////////////////////////
+;-------------------------------------------------------------------------------
+
+LSTROM:                                 ;ALL ABOVE CAN BE ROM
+                    ;HERE DOWN MUST BE RAM
+        ORG  08000H
+        ORG  0FF00H
+VARBGN: DS   55                         ;VARIABLE @(0)
+BUFFER: DS   64                         ;INPUT BUFFER
+BUFEND: DS   1                          ;BUFFER ENDS
+STKLMT: DS   1                          ;TOP LIMIT FOR STACK
+        END

snapshots/jotego_jtcores_pr1087/modules/jtframe/asm/z80/jtTinyBasic.asm

@@ -0,0 +1,1789 @@
+;*************************************************************
+;
+;                 TINY BASIC FOR ZILOG Z80
+;                       VERSION 2.0
+;                     BY LI-CHEN WANG
+;
+;                  MODIFIED AND TRANSLATED
+;                    TO INTEL MNEMONICS
+;                     BY ROGER RAUSKOLB
+;                      10 OCTOBER,1976
+;
+;                  MODIFIED AND TRANSLATED
+;                    TO ZILOG MNEMONICS
+;                      BY DOUG GABBARD
+;            www.retrodepot.net
+;
+;           RELEASED TO THE PUBLIC
+;                      10 OCTOBER,2017
+;                  YEAH, 41 YEARS LATER....
+;
+;                         @COPYLEFT
+;                   ALL WRONGS RESERVED
+;
+;*************************************************************
+; This code is derived from the original 8080 Tiny Basic.
+; It was first compiled in 8080 Mnemonics, then disassembled
+; into Zilog Mnemonics.  And then checked against the original
+; to ensure accuracy.  It was then partially enhanced with z80
+; specific code. And once done, it was then modified to work
+; with the G80-S Micro Computer. However, that portion of the
+; code has been left out in order to make this code a little
+; more portable.  There are only three routines that one needs
+; to write, and specifing the serial port's I/O address, in
+; order to make this version work with your own DIY computer.
+; Those routines can be found at the end of the source code.
+;
+; I hope you find good use for this relic. However, I would
+; ask that if you do find use for it, please put a reference
+; to me in your work. And please, distribute freely.
+;*************************************************************
+; Notes for JTFrame version:
+;  Adapted to work with GNU z80asm
+;  Added interrupt handling
+
+SerialPort:     EQU     0F0H            ; This the serial output port
+
+
+SPACE:          EQU     020H            ; Space
+TAB:            EQU     09H             ; HORIZONTAL TAB
+CTRLC:          EQU     03H             ; Control "C"
+CTRLG:          EQU     07H             ; Control "G"
+BKSP:           EQU     08H             ; Back space
+LF:             EQU     0AH             ; Line feed
+CS:             EQU     0CH             ; Clear screen
+CR:             EQU     0DH             ; Carriage return
+CTRLO:          EQU     0FH             ; Control "O"
+CTRLQ:          EQU     011H            ; Control "Q"
+CTRLR:          EQU     012H            ; Control "R"
+CTRLS:          EQU     013H            ; Control "S"
+CTRLU:          EQU     015H            ; Control "U"
+ESC:            EQU     01BH            ; Escape
+DEL:            EQU     07FH            ; Delete
+
+; Adjust to fit RAM mapping
+STACK:          EQU     087FFH          ; STACK (Last RAM address)
+OCSW:           EQU     08000H          ;SWITCH FOR OUTPUT
+CURRNT:         EQU     OCSW+1          ;POINTS FOR OUTPUT
+STKGOS:         EQU     OCSW+3          ;SAVES SP IN 'GOSUB'
+VARNXT:         EQU     OCSW+5          ;TEMP STORAGE
+STKINP:         EQU     OCSW+7          ;SAVES SP IN 'INPUT'
+LOPVAR:         EQU     OCSW+9          ;'FOR' LOOP SAVE AREA
+LOPINC:         EQU     OCSW+11         ;INCREMENT
+LOPLMT:         EQU     OCSW+13         ;LIMIT
+LOPLN:          EQU     OCSW+15         ;LINE NUMBER
+LOPPT:          EQU     OCSW+17         ;TEXT POINTER
+RANPNT:         EQU     OCSW+19         ;RANDOM NUMBER POINTER
+TXTUNF:         EQU     OCSW+21         ;->UNFILLED TEXT AREA
+TXTBGN:         EQU     OCSW+23         ;TEXT SAVE AREA BEGINS
+
+TXTEND:         EQU     08700H          ;TEXT SAVE AREA ENDS
+
+
+;*************************************************************
+; *** ZERO PAGE SUBROUTINES ***
+;
+; THE Z80 INSTRUCTION SET ALLOWS FOR 8 ROUTINES IN LOW MEMORY
+; THAT MAY BE CALLED BY RST 00H, 08H, 10H, 18H, 20H, 28H, 30H,
+; AND 38H.  THIS IS A ONE BYTE INSTRUCTION, AND IS FUNCTIONALLY
+; SIMILAR TO THE THREE BYTE INSTRUCTION 'CALL XXXX'. TINY BASIC
+; WILL USE THE RST INSTRUCTION FOR THE 7 MOST FREQUENTLY USED
+; SUBROUTINES. TWO OTHER SUBROUTINES (CRLF & TSTNUM) ARE ALSO
+; IN THIS SECTION. THEY CAN BE REACHED WITH 'CALL'.
+;*************************************************************
+
+DWA:    MACRO WHERE
+        DB   (WHERE >> 8) + 128
+        DB   WHERE & 0FFH
+        ENDM
+
+        ORG  0000H
+
+START:
+        LD SP,STACK                     ;*** COLD START ***
+        LD A,0FFH
+        JP INIT
+
+RST08:  EX (SP),HL                      ;*** TSTC OR RST 08H ***
+        RST 28H                         ;IGNORE BLANKS AND
+        CP (HL)                         ;TEST CHARACTER
+        JP TC1                          ;REST OF THIS IS AT TC1
+
+CRLF:
+        LD A,CR                         ;*** CRLF ***
+
+RST10:  PUSH AF                         ;*** OUTC OR RST 10H ***
+        LD A,(OCSW)                     ;PRINT CHARACTER ONLY
+        OR A                            ;IF OCSW SWITCH IS ON
+        JP OUTC                         ;REST OF THIS AT OUTC
+
+RST18:  CALL EXPR2                      ;*** EXPR OR RST 18H ***
+        PUSH HL                         ;EVALUATE AN EXPRESSION
+        JP EXPR1                        ;REST OF IT AT EXPR1
+        DB 'W'
+
+RST20:  LD A,H                          ;*** COMP OR RST 20H ***
+        CP D                            ;COMPARE HL WITH DE
+        RET NZ                          ;RETURN CORRECT C AND
+        LD A,L                          ;Z FLAGS
+        CP E                            ;BUT OLD A IS LOST
+        RET
+        DB 'AN'
+
+SS1:
+RST28:  LD A,(DE)                       ;*** IGNBLK/RST 28H ***
+        CP 20H                          ;IGNORE BLANKS
+        RET NZ                          ;IN TEXT (WHERE DE->)
+        INC DE                          ;AND RETURN THE FIRST
+        JP SS1                          ;NON-BLANK CHAR. IN A
+
+RST30:  POP AF                          ;*** FINISH/RST 30H ***
+        CALL FIN                        ;CHECK END OF COMMAND
+        JP QWHAT                        ;PRINT "WHAT?" IF WRONG
+        DB 'G'
+
+RST38:  RST 28H                         ;*** TSTV OR RST 38H ***
+        SUB 40H                         ;TEST VARIABLES
+        RET C                           ;C:NOT A VARIABLE
+        JR NZ,TV1                       ;NOT "@" ARRAY
+        INC DE                          ;IT IS THE "@" ARRAY
+        CALL PARN                       ;@ SHOULD BE FOLLOWED
+        ADD HL,HL                       ;BY (EXPR) AS ITS INDEX
+        JR C,QHOW                       ;IS INDEX TOO BIG?
+        PUSH DE                         ;WILL IT OVERWRITE
+        EX DE,HL                        ;TEXT?
+        CALL SIZE                       ;FIND SIZE OF FREE
+        RST 20H                         ;AND CHECK THAT
+        JP C,ASORRY                     ;IF SO, SAY "SORRY"
+        LD HL,VARBGN                    ;IF NOT GET ADDRESS
+        CALL SUBDE                      ;OF @(EXPR) AND PUT IT
+        POP DE                          ;IN HL
+        RET                             ;C FLAG IS CLEARED
+
+TV1:
+        CP 1BH                          ;NOT @, IS IT A TO Z?
+        CCF                             ;IF NOT RETURN C FLAG
+        RET C
+        INC DE                          ;IF A THROUGH Z
+        LD HL,VARBGN                    ;COMPUTE ADDRESS OF
+        RLCA                            ;THAT VARIABLE
+        ADD A,L                         ;AND RETURN IT IN HL
+        LD L,A                          ;WITH C FLAG CLEARED
+        LD A,00H
+        ADC A,H
+        LD H,A
+        RET
+
+NMI66:                                  ;MUST BE AT 66H
+        RETI
+
+TC1:
+        INC HL                          ;COMPARE THE BYTE THAT
+        JR Z,TC2                        ;FOLLOWS THE RST INST.
+        PUSH BC                         ;WITH THE TEXT (DE->)
+        LD C,(HL)                       ;IF NOT =, ADD THE 2ND
+        LD B,00H                        ;BYTE THAT FOLLOWS THE
+        ADD HL,BC                       ;RST TO THE OLD PC
+        POP BC                          ;I.E., DO A RELATIVE
+        DEC DE                          ;JUMP IF NOT =
+
+TC2:
+        INC DE                          ;IF =, SKIP THOSE BYTES
+        INC HL                          ;AND CONTINUE
+        EX (SP),HL
+        RET
+
+TSTNUM:
+        LD HL,0000H                     ;*** TSTNUM ***
+        LD B,H                          ;TEST IF THE TEXT IS
+        RST 28H                         ;A NUMBER
+
+TN1:
+        CP 30H                          ;IF NOT, RETURN 0 IN
+        RET C                           ;B AND HL
+        CP 3AH                          ;IF NUMBERS, CONVERT
+        RET NC                          ;TO BINARY IN HL AND
+        LD A,0F0H                       ;SET B TO # OF DIGITS
+        AND H                           ;IF H>255, THERE IS NO
+        JR NZ,QHOW                      ;ROOM FOR NEXT DIGIT
+        INC B                           ;B COUNTS # OF DIGITS
+        PUSH BC
+        LD B,H                          ;HL=10*HL+(NEW DIGIT)
+        LD C,L
+        ADD HL,HL                       ;WHERE 10* IS DONE BY
+        ADD HL,HL                       ;SHIFT AND ADD
+        ADD HL,BC
+        ADD HL,HL
+        LD A,(DE)                       ;AND (DIGIT) IS FROM
+        INC DE                          ;STRIPPING THE ASCII
+        AND 0FH                         ;CODE
+        ADD A,L
+        LD L,A
+        LD A,00H
+        ADC A,H
+        LD H,A
+        POP BC
+        LD A,(DE)                       ;DO THIS DIGIT AFTER
+        JP P,TN1                        ;DIGIT. S SAYS OVERFLOW
+
+QHOW:
+        PUSH DE                         ;*** ERROR "HOW?" ***
+AHOW:
+        LD DE,HOW
+        JP ERROR_ROUTINE
+
+
+HOW:    DB "HOW?",CR
+OK:     DB "OK",CR
+WHAT:   DB "WHAT?",CR
+SORRY:  DB "SORRY",CR
+
+;*************************************************************
+;
+; *** MAIN ***
+;
+; THIS IS THE MAIN LOOP THAT COLLECTS THE TINY BASIC PROGRAM
+; AND STORES IT IN THE MEMORY.
+;
+; AT START, IT PRINTS OUT "(CR)OK(CR)", AND INITIALIZES THE
+; STACK AND SOME OTHER INTERNAL VARIABLES.  THEN IT PROMPTS
+; ">" AND READS A LINE.  IF THE LINE STARTS WITH A NON-ZERO
+; NUMBER, THIS NUMBER IS THE LINE NUMBER.  THE LINE NUMBER
+; (IN 16 BIT BINARY) AND THE REST OF THE LINE (INCLUDING CR)
+; IS STORED IN THE MEMORY.  IF A LINE WITH THE SAME LINE
+; NUMBER IS ALREADY THERE, IT IS REPLACED BY THE NEW ONE.  IF
+; THE REST OF THE LINE CONSISTS OF A CR ONLY, IT IS NOT STORED
+; AND ANY EXISTING LINE WITH THE SAME LINE NUMBER IS DELETED.
+;
+; AFTER A LINE IS INSERTED, REPLACED, OR DELETED, THE PROGRAM
+; LOOPS BACK AND ASKS FOR ANOTHER LINE.  THIS LOOP WILL BE
+; TERMINATED WHEN IT READS A LINE WITH ZERO OR NO LINE
+; NUMBER; AND CONTROL IS TRANSFERED TO "DIRECT".
+;
+; TINY BASIC PROGRAM SAVE AREA STARTS AT THE MEMORY LOCATION
+; LABELED "TXTBGN" AND ENDS AT "TXTEND".  WE ALWAYS FILL THIS
+; AREA STARTING AT "TXTBGN", THE UNFILLED PORTION IS POINTED
+; BY THE CONTENT OF A MEMORY LOCATION LABELED "TXTUNF".
+;
+; THE MEMORY LOCATION "CURRNT" POINTS TO THE LINE NUMBER
+; THAT IS CURRENTLY BEING INTERPRETED.  WHILE WE ARE IN
+; THIS LOOP OR WHILE WE ARE INTERPRETING A DIRECT COMMAND
+; (SEE NEXT SECTION). "CURRNT" SHOULD POINT TO A 0.
+;*************************************************************
+
+RSTART:
+        LD SP,STACK
+
+ST1:
+        CALL CRLF                       ;AND JUMP TO HERE
+        LD DE,OK                        ;DE->STRING
+        SUB A                           ;A=0
+        CALL PRTSTG                     ;PRINT STRING UNTIL CR
+        LD HL,ST2+1                     ;LITERAL 0
+        LD (CURRNT),HL                  ;CURRENT->LINE # = 0
+
+ST2:
+        LD HL,0000H
+        LD (LOPVAR),HL
+        LD (STKGOS),HL
+
+ST3:
+        LD A,'>'                        ;PROMPT '>' AND
+        CALL GETLN                      ;READ A LINE
+        PUSH DE                         ;DE->END OF LINE
+        LD DE,BUFFER                    ;DE->BEGINNING OF LINE
+        CALL TSTNUM                     ;TEST IF IT IS A NUMBER
+        RST 28H
+        LD A,H                          ;HL=VALUE OF THE # OR
+        OR L                            ;0 IF NO # WAS FOUND
+        POP BC                          ;BC->END OF LINE
+        JP Z,DIRECT
+        DEC DE                          ;BACKUP DE AND SAVE
+        LD A,H                          ;VALUE OF LINE # THERE
+        LD (DE),A
+        DEC DE
+        LD A,L
+        LD (DE),A
+        PUSH BC                         ;BC,DE->BEGIN, END
+        PUSH DE
+        LD A,C
+        SUB E
+
+        PUSH AF                         ;A=# OF BYTES IN LINE
+        CALL FNDLN                      ;FIND THIS LINE IN SAVE
+        PUSH DE                         ;AREA, DE->SAVE AREA
+        JR NZ,ST4                       ;NZ:NOT FOUND, INSERT
+        PUSH DE                         ;Z:FOUND, DELETE IT
+        CALL FNDNXT                     ;FIND NEXT LINE
+                                        ;DE->NEXT LINE
+        POP BC                          ;BC->LINE TO BE DELETED
+        LD HL,(TXTUNF)                  ;HL->UNFILLED SAVE AREA
+        CALL MVUP                       ;MOVE UP TO DELETE
+        LD H,B                          ;TXTUNF->UNFILLED ARA
+        LD L,C
+        LD (TXTUNF),HL                  ;UPDATE
+
+ST4:
+        POP BC                          ;GET READY TO INSERT
+        LD HL,(TXTUNF)                  ;BUT FIRST CHECK IF
+        POP AF                          ;THE LENGTH OF NEW LINE
+        PUSH HL                         ;IS 3 (LINE # AND CR)
+        CP 03H                          ;THEN DO NOT INSERT
+        JR Z,RSTART                     ;MUST CLEAR THE STACK
+        ADD A,L                         ;COMPUTE NEW TXTUNF
+        LD L,A
+        LD A,00H
+        ADC A,H
+        LD H,A                          ;HL->NEW UNFILLED AREA
+        LD DE,TXTEND                    ;CHECK TO SEE IF THERE
+        RST 20H                         ;IS ENOUGH SPACE
+        JP NC,QSORRY                    ;SORRY, NO ROOM FOR IT
+        LD (TXTUNF),HL                  ;OK, UPDATE TXTUNF
+        POP DE                          ;DE->OLD UNFILLED AREA
+        CALL MVDOWN
+        POP DE                          ;DE->BEGIN, HL->END
+        POP HL
+        CALL MVUP                       ;MOVE NEW LINE TO SAVE
+        JR ST3                          ;AREA
+
+;*************************************************************
+;
+; WHAT FOLLOWS IS THE CODE TO EXECUTE DIRECT AND STATEMENT
+; COMMANDS.  CONTROL IS TRANSFERED TO THESE POINTS VIA THE
+; COMMAND TABLE LOOKUP CODE OF 'DIRECT' AND 'EXEC' IN LAST
+; SECTION.  AFTER THE COMMAND IS EXECUTED, CONTROL IS
+; TRANSFERED TO OTHERS SECTIONS AS FOLLOWS:
+;
+; FOR 'LIST', 'NEW', AND 'STOP': GO BACK TO 'RSTART'
+; FOR 'RUN': GO EXECUTE THE FIRST STORED LINE IF ANY, ELSE
+; GO BACK TO 'RSTART'.
+; FOR 'GOTO' AND 'GOSUB': GO EXECUTE THE TARGET LINE.
+; FOR 'RETURN' AND 'NEXT': GO BACK TO SAVED RETURN LINE.
+; FOR ALL OTHERS: IF 'CURRENT' -> 0, GO TO 'RSTART', ELSE
+; GO EXECUTE NEXT COMMAND.  (THIS IS DONE IN 'FINISH'.)
+;*************************************************************
+;
+; *** NEW *** STOP *** RUN (& FRIENDS) *** & GOTO ***
+;
+; 'NEW(CR)' SETS 'TXTUNF' TO POINT TO 'TXTBGN'
+;
+; 'STOP(CR)' GOES BACK TO 'RSTART'
+;
+; 'RUN(CR)' FINDS THE FIRST STORED LINE, STORE ITS ADDRESS (IN
+; 'CURRENT'), AND START EXECUTE IT.  NOTE THAT ONLY THOSE
+; COMMANDS IN TAB2 ARE LEGAL FOR STORED PROGRAM.
+;
+; THERE ARE 3 MORE ENTRIES IN 'RUN':
+; 'RUNNXL' FINDS NEXT LINE, STORES ITS ADDR. AND EXECUTES IT.
+; 'RUNTSL' STORES THE ADDRESS OF THIS LINE AND EXECUTES IT.
+; 'RUNSML' CONTINUES THE EXECUTION ON SAME LINE.
+;
+; 'GOTO EXPR(CR)' EVALUATES THE EXPRESSION, FIND THE TARGET
+; LINE, AND JUMP TO 'RUNTSL' TO DO IT.
+;*************************************************************
+
+NEW:
+        CALL ENDCHK                     ;*** NEW(CR) ***
+        LD HL,TXTBGN
+        LD (TXTUNF),HL
+STOP:
+        CALL ENDCHK                     ;*** STOP(CR) ***
+        JP RSTART
+RUN:
+        CALL ENDCHK                     ;*** RUN(CR) ***
+        LD DE,TXTBGN                    ;FIRST SAVED LINE
+RUNNXL:
+        LD HL,00H                       ;*** RUNNXL ***
+        CALL FNDLP                      ;FIND WHATEVER LINE #
+        JP C,RSTART                     ;C:PASSED TXTUNF, QUIT
+RUNTSL:
+        EX DE,HL                        ;*** RUNTSL ***
+        LD (CURRNT),HL                  ;SET 'CURRENT'->LINE #
+        EX DE,HL
+        INC DE                          ;BUMP PASS LINE #
+        INC DE
+RUNSML:
+        CALL CHKIO                      ;*** RUNSML ***
+        LD HL,TAB2-1                    ;FIND COMMAND IN TAB2
+        JP EXEC                         ;AND EXECUTE IT
+GOTO:
+        RST 18H                         ;*** GOTO EXPR ***
+        PUSH DE                         ;SAVE FOR ERROR ROUTINE
+        CALL ENDCHK                     ;MUST FIND A CR
+        CALL FNDLN                      ;FIND THE TARGET LINE
+        JP NZ,AHOW                      ;NO SUCH LINE #
+        POP AF                          ;CLEAR THE PUSH DE
+        JR RUNTSL                       ;GO DO IT
+
+;*************************************************************
+;
+; *** LIST *** & PRINT ***
+;
+; LIST HAS TWO FORMS:
+; 'LIST(CR)' LISTS ALL SAVED LINES
+; 'LIST #(CR)' START LIST AT THIS LINE #
+; YOU CAN STOP THE LISTING BY CONTROL C KEY
+;
+; PRINT COMMAND IS 'PRINT ....;' OR 'PRINT ....(CR)'
+; WHERE '....' IS A LIST OF EXPRESIONS, FORMATS, BACK-
+; ARROWS, AND STRINGS.  THESE ITEMS ARE SEPERATED BY COMMAS.
+;
+; A FORMAT IS A POUND SIGN FOLLOWED BY A NUMBER.  IT CONTROLS
+; THE NUMBER OF SPACES THE VALUE OF A EXPRESION IS GOING TO
+; BE PRINTED.  IT STAYS EFFECTIVE FOR THE REST OF THE PRINT
+; COMMAND UNLESS CHANGED BY ANOTHER FORMAT.  IF NO FORMAT IS
+; SPECIFIED, 6 POSITIONS WILL BE USED.
+;
+; A STRING IS QUOTED IN A PAIR OF SINGLE QUOTES OR A PAIR OF
+; DOUBLE QUOTES.
+;
+; A BACK-ARROW MEANS GENERATE A (CR) WITHOUT (LF)
+;
+; A (CRLF) IS GENERATED AFTER THE ENTIRE LIST HAS BEEN
+; PRINTED OR IF THE LIST IS A NULL LIST.  HOWEVER IF THE LIST
+; ENDED WITH A COMMA, NO (CRLF) IS GENERATED.
+;*************************************************************
+
+LIST:
+        CALL TSTNUM                     ;TEST IF THERE IS A #
+        CALL ENDCHK                     ;IF NO # WE GET A 0
+        CALL FNDLN                      ;FIND THIS OR NEXT LINE
+LS1:
+        JP C,RSTART                     ;C:PASSED TXTUNF
+        CALL PRTLN                      ;PRINT THE LINE
+        CALL CHKIO                      ;STOP IF HIT CONTROL-C
+        CALL FNDLP                      ;FIND NEXT LINE
+        JR LS1                          ;AND LOOP BACK
+PRINT:
+        LD C,06H                        ;C = # OF SPACES
+        RST 08H                         ;F NULL LIST & ";"
+        DB 3BH
+        DB PR2-$-1
+        CALL CRLF                       ;GIVE CR-LF AND
+        JR RUNSML                       ;CONTINUE SAME LINE
+PR2:
+        RST 08H                         ;IF NULL LIST (CR)
+        DB CR
+        DB PR0-$-1
+        CALL CRLF                       ;ALSO GIVE CR-LF AND
+        JR RUNNXL                       ;GO TO NEXT LINE
+PR0:
+        RST 08H                         ;ELSE IS IT FORMAT?
+        DB '#'
+        DB PR1-$-1
+        RST 18H                         ;YES, EVALUATE EXPR.
+        LD C,L                          ;AND SAVE IT IN C
+        JR PR3                          ;LOOK FOR MORE TO PRINT
+PR1:
+        CALL QTSTG                      ;OR IS IT A STRING?
+        JR PR8                          ;IF NOT, MUST BE EXPR.
+PR3:
+        RST 08H                         ;IF ",", GO FIND NEXT
+        DB ','
+        DB PR6-$-1
+        CALL FIN                        ;IN THE LIST.
+        JR PR0                          ;LIST CONTINUES
+PR6:
+        CALL CRLF                       ;LIST ENDS
+        RST 30H
+PR8:
+        RST 18H                         ;EVALUATE THE EXPR
+        PUSH BC
+        CALL PRTNUM                     ;PRINT THE VALUE
+        POP BC
+        JR PR3                          ;MORE TO PRINT?
+
+;*************************************************************
+;
+; *** GOSUB *** & RETURN ***
+;
+; 'GOSUB EXPR;' OR 'GOSUB EXPR (CR)' IS LIKE THE 'GOTO'
+; COMMAND, EXCEPT THAT THE CURRENT TEXT POINTER, STACK POINTER
+; ETC. ARE SAVE SO THAT EXECUTION CAN BE CONTINUED AFTER THE
+; SUBROUTINE 'RETURN'.  IN ORDER THAT 'GOSUB' CAN BE NESTED
+; (AND EVEN RECURSIVE), THE SAVE AREA MUST BE STACKED.
+; THE STACK POINTER IS SAVED IN 'STKGOS', THE OLD 'STKGOS' IS
+; SAVED IN THE STACK.  IF WE ARE IN THE MAIN ROUTINE, 'STKGOS'
+; IS ZERO (THIS WAS DONE BY THE "MAIN" SECTION OF THE CODE),
+; BUT WE STILL SAVE IT AS A FLAG FOR NO FURTHER 'RETURN'S.
+;
+; 'RETURN(CR)' UNDOS EVERYTHING THAT 'GOSUB' DID, AND THUS
+; RETURN THE EXECUTION TO THE COMMAND AFTER THE MOST RECENT
+; 'GOSUB'.  IF 'STKGOS' IS ZERO, IT INDICATES THAT WE
+; NEVER HAD A 'GOSUB' AND IS THUS AN ERROR.
+;*************************************************************
+
+GOSUB:
+        CALL PUSHA                      ;SAVE THE CURRENT "FOR"
+        RST 18H                         ;PARAMETERS
+        PUSH DE                         ;AND TEXT POINTER
+        CALL FNDLN                      ;FIND THE TARGET LINE
+        JP NZ,AHOW                      ;NOT THERE. SAY "HOW?"
+        LD HL,(CURRNT)                  ;FOUND IT, SAVE OLD.
+        PUSH HL                         ;'CURRNT' OLD 'STKGOS'
+        LD HL,(STKGOS)
+        PUSH HL
+        LD HL,0000H                     ;AND LOAD NEW ONES
+        LD (LOPVAR),HL
+        ADD HL,SP
+        LD (STKGOS),HL
+        JP RUNTSL                       ;THEN RUN THAT LINE
+RETURN:
+        CALL ENDCHK                     ;THERE MUST BE A CR
+        LD HL,(STKGOS)                  ;OLD STACK POINTER
+        LD A,H                          ;0 MEANS NOT EXIST
+        OR L
+        JP Z,QWHAT                      ;SO, WE SAY: "WHAT?"
+        LD SP,HL                        ;ELSE, RESTORE IT
+        POP HL
+        LD (STKGOS),HL                  ;AND THE OLD "STKGOS"
+        POP HL
+        LD (CURRNT),HL                  ;AND THE OLD 'CURRNT'
+        POP DE                          ;OLD TEXT POINTER
+        CALL POPA                       ;OLD "FOR" PARAMETERS
+        RST 30H                         ;AND WE ARE BACK HOME
+
+;*************************************************************
+;
+; *** FOR *** & NEXT ***
+;
+; 'FOR' HAS TWO FORMS:
+; 'FOR VAR=EXP1 TO EXP2 STEP EXP3' AND 'FOR VAR=EXP1 TO EXP2'
+; THE SECOND FORM MEANS THE SAME THING AS THE FIRST FORM WITH
+; EXP3=1.  (I.E., WITH A STEP OF +1.)
+; TBI WILL FIND THE VARIABLE VAR, AND SET ITS VALUE TO THE
+; CURRENT VALUE OF EXP1.  IT ALSO EVALUATES EXP2 AND EXP3
+; AND SAVE ALL THESE TOGETHER WITH THE TEXT POINTER ETC. IN
+; THE 'FOR' SAVE AREA, WHICH CONSISTS OF 'LOPVAR', 'LOPINC',
+; 'LOPLMT', 'LOPLN', AND 'LOPPT'.  IF THERE IS ALREADY SOME-
+; THING IN THE SAVE AREA (THIS IS INDICATED BY A NON-ZERO
+; 'LOPVAR'), THEN THE OLD SAVE AREA IS SAVED IN THE STACK
+; BEFORE THE NEW ONE OVERWRITES IT.
+; TBI WILL THEN DIG IN THE STACK AND FIND OUT IF THIS SAME
+; VARIABLE WAS USED IN ANOTHER CURRENTLY ACTIVE 'FOR' LOOP.
+; IF THAT IS THE CASE, THEN THE OLD 'FOR' LOOP IS DEACTIVATED.
+; (PURGED FROM THE STACK..)
+;
+; 'NEXT VAR' SERVES AS THE LOGICAL (NOT NECESSARILLY PHYSICAL)
+; END OF THE 'FOR' LOOP.  THE CONTROL VARIABLE VAR. IS CHECKED
+; WITH THE 'LOPVAR'.  IF THEY ARE NOT THE SAME, TBI DIGS IN
+; THE STACK TO FIND THE RIGHT ONE AND PURGES ALL THOSE THAT
+; DID NOT MATCH.  EITHER WAY, TBI THEN ADDS THE 'STEP' TO
+; THAT VARIABLE AND CHECK THE RESULT WITH THE LIMIT.  IF IT
+; IS WITHIN THE LIMIT, CONTROL LOOPS BACK TO THE COMMAND
+; FOLLOWING THE 'FOR'.  IF OUTSIDE THE LIMIT, THE SAVE AREA
+; IS PURGED AND EXECUTION CONTINUES.
+;*************************************************************
+
+FOR:
+        CALL PUSHA                      ;SAVE THE OLD SAVE AREA
+        CALL SETVAL                     ;SET THE CONTROL VAR.
+        DEC HL                          ;HL IS ITS ADDRESS
+        LD (LOPVAR),HL                  ;SAVE THAT
+        LD HL,TAB5-1                    ;USE 'EXEC' TO LOOK
+        JP EXEC                         ;FOR THE WORK 'TO'
+FR1:
+        RST 18H                         ;EVALUATE THE LIMITE
+        LD (LOPLMT),HL                  ;SAVE THAT
+        LD HL,TAB6-1                    ;USE 'EXEC' TO LOOK
+        JP EXEC                         ;FOR THE WORD 'STEP'
+FR2:
+        RST 18H                         ;FOUND IT, GET STEP
+        JR FR4
+FR3:
+        LD HL,0001H                     ;NOT FOUND, SET TO 1
+FR4:
+        LD (LOPINC),HL                  ;SAVE THAT TOO
+FR5:
+        LD HL,(CURRNT)                  ;SAVE CURRENT LINE #
+        LD (LOPLN),HL
+        EX DE,HL                        ;AND TEXT POINTER
+        LD (LOPPT),HL
+        LD BC,0AH                       ;DIG INTO STACK TO
+        LD HL,(LOPVAR)                  ;FIND 'LOPVAR'
+        EX DE,HL
+        LD H,B
+        LD L,B                          ;HL=0 NOW
+        ADD HL,SP                       ;HERE IS THE STACK
+        DB 3EH                          ;DISASSEMBLY SAID "ld a,09h"
+FR7:
+        ADD HL,BC                       ;EACH LEVEL IS 10 DEEP - DIS = 09
+        LD A,(HL)                       ;GET THAT OLD 'LOPVAR'
+        INC HL
+        OR (HL)
+        JR Z,FR8                        ;0 SAYS NO MORE IN IT
+        LD A,(HL)
+        DEC HL
+        CP D                            ;SAME AS THIS ONE?
+        JR NZ,FR7
+        LD A,(HL)                       ;THE OTHER HALF?
+        CP E
+        JR NZ,FR7
+        EX DE,HL                        ;YES, FOUND ONE
+        LD HL,0000H
+        ADD HL,SP                       ;TRY TO MOVE SP
+        LD B,H
+        LD C,L
+        LD HL,000AH
+        ADD HL,DE
+        CALL MVDOWN                     ;AND PURGE 10 WORDS
+        LD SP,HL                        ;IN THE STACK
+FR8:
+        LD HL,(LOPPT)                   ;JOB DONE, RESTORE DE
+        EX DE,HL
+        RST 30H                         ;AND CONTINUE
+;
+NEXT:
+        RST 38H                         ;GET ADDRESS OF VAR.
+        JP C,QWHAT                      ;NO VARIABLE, "WHAT?"
+        LD (VARNXT),HL                  ;YES, SAVE IT
+NX0:
+        PUSH DE                         ;SAVE TEXT POINTER
+        EX DE,HL
+        LD HL,(LOPVAR)                  ;GET VAR. IN 'FOR'
+        LD A,H
+        OR L                            ;0 SAYS NEVER HAD ONE
+        JP Z,AWHAT                      ;SO WE ASK: "WHAT?"
+        RST 20H                         ;ELSE WE CHECK THEM
+        JR Z,NX3                        ;OK, THEY AGREE
+        POP DE                          ;NO, LET'S SEE
+        CALL POPA                       ;PURGE CURRENT LOOP
+        LD HL,(VARNXT)                  ;AND POP ONE LEVEL
+        JR NX0                          ;GO CHECK AGAIN
+NX3:
+        LD E,(HL)                       ;COME HERE WHEN AGREED
+        INC HL
+        LD D,(HL)                       ;DE=VALUE OF VAR.
+        LD HL,(LOPINC)
+        PUSH HL
+        LD A,H
+        XOR D
+        LD A,D
+        ADD HL,DE                       ;ADD ONE STEP
+        JP M,NX4
+        XOR H
+        JP M,NX5
+NX4:
+        EX DE,HL
+        LD HL,(LOPVAR)                  ;PUT IT BACK
+        LD (HL),E
+        INC HL
+        LD (HL),D
+        LD HL,(LOPLMT)                  ;HL->LIMIT
+        POP AF                          ;OLD HL
+        OR A
+        JP P,NX1                        ;STEP > 0
+        EX DE,HL                        ;STEP < 0
+NX1:
+        CALL CKHLDE                     ;COMPARE WITH LIMIT
+        POP DE                          ;RESTORE TEXT POINTER
+        JR C,NX2                        ;OUTSIDE LIMIT
+        LD HL,(LOPLN)                   ;WITHIN LIMIT, GO
+        LD (CURRNT),HL                  ;BACK TO THE SAVED
+        LD HL,(LOPPT)                   ;'CURRNT' AND TEXT
+        EX DE,HL                        ;POINTER
+        RST 30H
+NX5:
+        POP HL
+        POP DE
+NX2:
+        CALL POPA                       ;PURGE THIS LOOP
+        RST 30H
+
+;*************************************************************
+;
+; *** REM *** IF *** INPUT *** & LET (& DEFLT) ***
+;
+; 'REM' CAN BE FOLLOWED BY ANYTHING AND IS IGNORED BY TBI.
+; TBI TREATS IT LIKE AN 'IF' WITH A FALSE CONDITION.
+;
+; 'IF' IS FOLLOWED BY AN EXPR. AS A CONDITION AND ONE OR MORE
+; COMMANDS (INCLUDING OTHER 'IF'S) SEPERATED BY SEMI-COLONS.
+; NOTE THAT THE WORD 'THEN' IS NOT USED.  TBI EVALUATES THE
+; EXPR. IF IT IS NON-ZERO, EXECUTION CONTINUES.  IF THE
+; EXPR. IS ZERO, THE COMMANDS THAT FOLLOWS ARE IGNORED AND
+; EXECUTION CONTINUES AT THE NEXT LINE.
+;
+; 'INPUT' COMMAND IS LIKE THE 'PRINT' COMMAND, AND IS FOLLOWED
+; BY A LIST OF ITEMS.  IF THE ITEM IS A STRING IN SINGLE OR
+; DOUBLE QUOTES, OR IS A BACK-ARROW, IT HAS THE SAME EFFECT AS
+; IN 'PRINT'.  IF AN ITEM IS A VARIABLE, THIS VARIABLE NAME IS
+; PRINTED OUT FOLLOWED BY A COLON.  THEN TBI WAITS FOR AN
+; EXPR. TO BE TYPED IN.  THE VARIABLE IS THEN SET TO THE
+; VALUE OF THIS EXPR.  IF THE VARIABLE IS PROCEDED BY A STRING
+; (AGAIN IN SINGLE OR DOUBLE QUOTES), THE STRING WILL BE
+; PRINTED FOLLOWED BY A COLON.  TBI THEN WAITS FOR INPUT EXPR.
+; AND SET THE VARIABLE TO THE VALUE OF THE EXPR.
+;
+; IF THE INPUT EXPR. IS INVALID, TBI WILL PRINT "WHAT?",
+; "HOW?" OR "SORRY" AND REPRINT THE PROMPT AND REDO THE INPUT.
+; THE EXECUTION WILL NOT TERMINATE UNLESS YOU TYPE CONTROL-C.
+; THIS IS HANDLED IN 'INPERR'.
+;
+; 'LET' IS FOLLOWED BY A LIST OF ITEMS SEPERATED BY COMMAS.
+; EACH ITEM CONSISTS OF A VARIABLE, AN EQUAL SIGN, AND AN EXPR.
+; TBI EVALUATES THE EXPR. AND SET THE VARIABLE TO THAT VALUE.
+; TBI WILL ALSO HANDLE 'LET' COMMAND WITHOUT THE WORD 'LET'.
+; THIS IS DONE BY 'DEFLT'.
+;*************************************************************
+
+REM:
+        LD HL,0000H                     ;*** REM ***
+        DB 3EH                          ;THIS IS LIKE 'IF 0'
+IFF:
+        RST 18H                         ;*** IF ***
+        LD A,H                          ;IS THE EXPR.=0?
+        OR L
+        JP NZ,RUNSML                    ;NO, CONTINUE
+        CALL FNDSKP                     ;YES, SKIP REST OF LINE
+        JP NC,RUNTSL                    ;AND RUN THE NEXT LINE
+        JP RSTART                       ;IF NO NEXT, RE-START
+INPERR:
+        LD HL,(STKINP)                  ;*** INPERR ***
+        LD SP,HL                        ;RESTORE OLD SP
+        POP HL                          ;AND OLD 'CURRNT'
+        LD (CURRNT),HL
+        POP DE                          ;AND OLD TEXT POINTER
+        POP DE                          ;REDO INPUT
+INPUT:                                  ;*** INPUT ***
+IP1:
+        PUSH DE                         ;SAVE IN CASE OF ERROR
+        CALL QTSTG                      ;IS NEXT ITEM A STRING?
+        JR IP2                          ;NO
+        RST 38H                         ;YES, BUT FOLLOWED BY A
+        JR C,IP4                        ;VARIABLE? NO.
+        JR IP3                          ;YES. INPUT VARIABLE
+IP2:
+        PUSH DE                         ;SAVE FOR 'PRTSTG'
+        RST 38H                         ;MUST BE VARIABLE NOW
+        JP C,QWHAT                      ;"WHAT?" IT IS NOT?
+        LD A,(DE)                       ;GET READY FOR 'PRTSTR'
+        LD C,A
+        SUB A
+        LD (DE),A
+        POP DE
+        CALL PRTSTG                     ;PRINT STRING AS PROMPT
+        LD A,C                          ;RESTORE TEXT
+        DEC DE
+        LD (DE),A
+IP3:
+        PUSH DE                         ;SAVE TEXT POINTER
+        EX DE,HL
+        LD HL,(CURRNT)                  ;ALSO SAVE 'CURRNT'
+        PUSH HL
+        LD HL,IP1                       ;A NEGATIVE NUMBER
+        LD (CURRNT),HL                  ;AS A FLAG
+        LD HL,0000H                     ;SAVE SP TOO
+        ADD HL,SP
+        LD (STKINP),HL
+        PUSH DE                         ;OLD HL
+        LD A,3AH                        ;PRINT THIS TOO
+        CALL GETLN                      ;AND GET A LINE
+        LD DE,BUFFER                    ;POINTS TO BUFFER
+        RST 18H                         ;EVALUATE INPUT
+        NOP                             ;CAN BE 'CALL ENDCHK'
+        NOP
+        NOP
+        POP DE                          ;OK,GET OLD HL
+        EX DE,HL
+        LD (HL),E                       ;SAVE VALUE IN VAR.
+        INC HL
+        LD (HL),D
+        POP HL                          ;GET OLD 'CURRNT'
+        LD (CURRNT),HL
+        POP DE                          ;AND OLD TEXT POINTER
+IP4:
+        POP AF                          ;PURGE JUNK IN STACK
+        RST 08H                         ;IS NEXT CH. ','?
+        DB ','
+        DB IP5-$-1
+        JR IP1                          ;YES, MORE ITEMS.
+IP5:
+        RST 30H
+DEFLT:
+        LD A,(DE)                       ;***  DEFLT ***
+        CP CR                           ;EMPTY LINE IS OK
+        JR Z,LT1                        ;ELSE IT IS 'LET'
+LET:
+        CALL SETVAL                     ;*** LET ***
+        RST 08H                         ;SET VALUE TO VAR
+        DB ','                          ;---DISASSEMBLE = INC L
+        DB LT1-$-1                      ;---DISASSEMBLE = INC BC
+        JR LET                          ;ITEM BY ITEM
+LT1:
+        RST 30H                         ;UNTIL FINISH
+;*************************************************************
+;
+; *** EXPR ***
+;
+; 'EXPR' EVALUATES ARITHMETICAL OR LOGICAL EXPRESSIONS.
+; <EXPR>::<EXPR2>
+;         <EXPR2><REL.OP.><EXPR2>
+; WHERE <REL.OP.> IS ONE OF THE OPERATORS IN TAB8 AND THE
+; RESULT OF THESE OPERATIONS IS 1 IF TRUE AND 0 IF FALSE.
+; <EXPR2>::=(+ OR -)<EXPR3>(+ OR -<EXPR3>)(....)
+; WHERE () ARE OPTIONAL AND (....) ARE OPTIONAL REPEATS.
+; <EXPR3>::=<EXPR4>(* OR /><EXPR4>)(....)
+; <EXPR4>::=<VARIABLE>
+;           <FUNCTION>
+;           (<EXPR>)
+; <EXPR> IS RECURSIVE SO THAT VARIABLE '@' CAN HAVE AN <EXPR>
+; AS INDEX, FUNCTIONS CAN HAVE AN <EXPR> AS ARGUMENTS, AND
+; <EXPR4> CAN BE AN <EXPR> IN PARANTHESE.
+;*************************************************************
+
+EXPR1:
+        LD HL,TAB8-1                    ;LOOKUP REL.OP.
+        JP EXEC                         ;GO DO IT
+XP11:
+        CALL XP18                       ;REL.OP.">="
+        RET C                           ;NO, RETURN HL=0
+        LD L,A                          ;YES, RETURN HL=1
+        RET
+XP12:
+        CALL XP18                       ;REL.OP."#"
+        RET Z                           ;FALSE, RETURN HL=0
+        LD L,A                          ;TRUE, RETURN HL=1
+        RET
+XP13:
+        CALL XP18                       ;REL.OP.">"
+        RET Z                           ;FALSE
+        RET C                           ;ALSO FALSE, HL=0
+        LD L,A                          ;TRUE, HL=1
+        RET
+XP14:
+        CALL XP18                       ;REL.OP."<="
+        LD L,A                          ;SET HL=1
+        RET Z                           ;REL. TRUE, RETURN
+        RET C
+        LD L,H                          ;ELSE SET HL=0
+        RET
+XP15:
+        CALL XP18                       ;REL.OP."="
+        RET NZ                          ;FALSE, RETURN HL=0
+        LD L,A                          ;ELSE SET HL=1
+        RET
+XP16:
+        CALL XP18                       ;REL.OP."<"
+        RET NC                          ;FALSE, RETURN HL=0
+        LD L,A                          ;ELSE SET HL=1
+        RET
+XP17:
+        POP HL                          ;NOT .REL.OP
+        RET                             ;RETURN HL=<EXPR2>
+XP18:
+        LD A,C                          ;SUBROUTINE FOR ALL
+        POP HL                          ;REL.OP.'S
+        POP BC
+        PUSH HL                         ;REVERSE TOP OF STACK
+        PUSH BC
+        LD C,A
+        CALL EXPR2                      ;GET 2ND <EXPR2>
+        EX DE,HL                        ;VALUE IN DE NOW
+        EX (SP),HL                      ;1ST <EXPR2> IN HL
+        CALL CKHLDE                     ;COMPARE 1ST WITH 2ND
+        POP DE                          ;RESTORE TEXT POINTER
+        LD HL,0000H                     ;SET HL=0, A=1
+        LD A,01H
+        RET
+EXPR2:
+        RST 08H                         ;NEGATIVE SIGN?
+        DB '-'
+        DB XP21-$-1
+        LD HL,0000H                     ;YES, FAKE '0-'
+        JR XP26                         ;TREAT LIKE SUBTRACT
+XP21:
+        RST 08H                         ;POSITIVE SIGN? IGNORE
+        DB '+'
+        DB XP22-$-1
+XP22:
+        CALL EXPR3                      ;1ST <EXPR3>
+XP23:
+        RST 08H                         ;ADD?
+        DB  '+'
+        DB XP25-$-1
+        PUSH HL                         ;YES, SAVE VALUE
+        CALL EXPR3                      ;GET 2ND <EXPR3>
+XP24:
+        EX DE,HL                        ;2ND IN DE
+        EX (SP),HL                      ;1ST IN HL
+        LD A,H                          ;COMPARE SIGN
+        XOR D
+        LD A,D
+        ADD HL,DE
+        POP DE                          ;RESTORE TEXT POINTER
+        JP M,XP23                       ;1ST AND 2ND SIGN DIFFER
+        XOR H                           ;1ST AND 2ND SIGN EQUAL
+        JP P,XP23                       ;SO IS RESULT
+        JP QHOW                         ;ELSE WE HAVE OVERFLOW
+XP25:
+        RST 08H                         ;SUBTRACT?
+        DB '-'
+        DB XP42-$-1
+XP26:
+        PUSH HL                         ;YES, SAVE 1ST <EXPR3>
+        CALL EXPR3                      ;GET 2ND <EXPR3>
+        CALL CHGSGN                     ;NEGATE
+        JR XP24                         ;AND ADD THEM
+;
+EXPR3:
+        CALL EXPR4                      ;GET 1ST <EXPR4>
+XP31:
+        RST 08H                         ;MULTIPLY?
+        DB '*'
+        DB XP34-$-1
+        PUSH HL                         ;YES, SAVE 1ST
+        CALL EXPR4                      ;AND GET 2ND <EXPR4>
+        LD B,00H                        ;CLEAR B FOR SIGN
+        CALL CHKSGN                     ;CHECK SIGN
+        EX (SP),HL                      ;1ST IN HL
+        CALL CHKSGN                     ;CHECK SIGN OF 1ST
+        EX DE,HL
+        EX (SP),HL
+        LD A,H                          ;IS HL > 255 ?
+        OR A
+        JR Z,XP32                       ;NO
+        LD A,D                          ;YES, HOW ABOUT DE
+        OR D
+        EX DE,HL                        ;PUT SMALLER IN HL
+        JP NZ,AHOW                      ;ALSO >, WILL OVERFLOW
+XP32:
+        LD A,L                          ;THIS IS DUMB
+        LD HL,0000H                     ;CLEAR RESULT
+        OR A                            ;ADD AND COUNT
+        JR Z,XP35
+XP33:
+        ADD HL,DE
+        JP C,AHOW                       ;OVERFLOW
+        DEC A
+        JR NZ,XP33
+        JR XP35                         ;FINISHED
+XP34:
+        RST 08H                         ;DIVIDE?
+        DB '/'
+        DB XP42-$-1
+        PUSH HL                         ;YES, SAVE 1ST <EXPR4>
+        CALL EXPR4                      ;AND GET THE SECOND ONE
+        LD B,00H                        ;CLEAR B FOR SIGN
+        CALL CHKSGN                     ;CHECK SIGN OF 2ND
+        EX (SP),HL                      ;GET 1ST IN HL
+        CALL CHKSGN                     ;CHECK SIGN OF 1ST
+        EX DE,HL
+        EX (SP),HL
+        EX DE,HL
+        LD A,D                          ;DIVIDE BY 0?
+        OR E
+        JP Z,AHOW                       ;SAY "HOW?"
+        PUSH BC                         ;ELSE SAVE SIGN
+        CALL DIVIDE                     ;USE SUBROUTINE
+        LD H,B                          ;RESULT IN HL NOW
+        LD L,C
+        POP BC                          ;GET SIGN BACK
+XP35:
+        POP DE                          ;AND TEXT POINTER
+        LD A,H                          ;HL MUST BE +
+        OR A
+        JP M,QHOW                       ;ELSE IT IS OVERFLOW
+        LD A,B
+        OR A
+        CALL M,CHGSGN                   ;CHANGE SIGN IF NEEDED
+        JR XP31                         ;LOOK FOR MORE TERMS
+EXPR4:
+        LD HL,TAB4-1                    ;FIND FUNCTION IN TAB4
+        JP EXEC                         ;AND GO DO IT
+XP40:
+        RST 38H                         ;NO, NOT A FUNCTION
+        JR C,XP41                       ;NOR A VARIABLE
+        LD A,(HL)                       ;VARIABLE
+        INC HL
+        LD H,(HL)                       ;VALUE IN HL
+        LD L,A
+        RET
+XP41:
+        CALL TSTNUM                     ;OR IS IT A NUMBER
+        LD A,B                          ;# OF DIGIT
+        OR A
+        RET NZ                          ;OK
+PARN:
+        RST 08H
+        DB '('
+        DB XP43-$-1
+        RST 18H                         ;"(EXPR)"
+        RST 08H
+        DB ')'
+        DB XP43-$-1
+XP42:
+        RET
+XP43:
+        JP QWHAT                        ;ELSE SAY: "WHAT?"
+RND:
+        CALL PARN                       ;*** RND(EXPR) ***
+        LD A,H                          ;EXPR MUST BE +
+        OR A
+        JP M,QHOW
+        OR L                            ;AND NON-ZERO
+        JP Z,QHOW
+        PUSH DE                         ;SAVE BOTH
+        PUSH HL
+        LD HL,(RANPNT)                  ;GET MEMORY AS RANDOM
+        LD DE,LSTROM                    ;NUMBER
+        RST 20H
+        JR C,RA1                        ;WRAP AROUND IF LAST
+        LD HL,START
+RA1:
+        LD E,(HL)
+        INC HL
+        LD D,(HL)
+        LD (RANPNT),HL
+        POP HL
+        EX DE,HL
+        PUSH BC
+        CALL DIVIDE                     ;RND (N)=MOD(M,N)+1
+        POP BC
+        POP DE
+        INC HL
+        RET
+ABS:
+        CALL PARN                       ;*** ABS (EXPR) ***
+        DEC DE
+        CALL CHKSGN                     ;CHECK SIGN
+        INC DE
+        RET
+SIZE:
+        LD HL,(TXTUNF)                  ;*** SIZE ***
+        PUSH DE                         ;GET THE NUMBER OF FREE
+        EX DE,HL                        ;BYTES BETWEEN 'TXTUNF'
+        LD HL,VARBGN                    ;AND 'VARBGN'
+        CALL SUBDE
+        POP DE
+        RET
+;*************************************************************
+;
+; *** DIVIDE *** SUBDE *** CHKSGN *** CHGSGN *** & CKHLDE ***
+;
+; 'DIVIDE' DIVIDES HL BY DE, RESULT IN BC, REMAINDER IN HL
+;
+; 'SUBDE' SUBSTRACTS DE FROM HL
+;
+; 'CHKSGN' CHECKS SIGN OF HL.  IF +, NO CHANGE.  IF -, CHANGE
+; SIGN AND FLIP SIGN OF B.
+;
+; 'CHGSGN' CHECKS SIGN N OF HL AND B UNCONDITIONALLY.
+;
+; 'CKHLDE' CHECKS SIGN OF HL AND DE.  IF DIFFERENT, HL AND DE
+; ARE INTERCHANGED.  IF SAME SIGN, NOT INTERCHANGED.  EITHER
+; CASE, HL DE ARE THEN COMPARED TO SET THE FLAGS.
+;*************************************************************
+
+DIVIDE:
+        PUSH HL                         ;*** DIVIDE ***
+        LD L,H                          ;DIVIDE H BY DE
+        LD H,00H
+        CALL DV1
+        LD B,C                          ;SAVE RESULT IN B
+        LD A,L                          ;(REMAINDER+L)/DE
+        POP HL
+        LD H,A
+DV1:
+        LD C,0FFH                       ;RESULT IN C
+DV2:
+        INC C                           ;DUMB ROUTINE
+        CALL SUBDE                      ;DIVIDE BY SUBTRACT
+        JR NC,DV2                       ;AND COUNT
+        ADD HL,DE
+        RET
+SUBDE:
+        LD A,L                          ;*** SUBDE ***
+        SUB E                           ;SUBSTRACT DE FROM
+        LD L,A                          ;HL
+        LD A,H
+        SBC A,D
+        LD H,A
+        RET
+CHKSGN:
+        LD A,H                          ;*** CHKSGN ***
+        OR A                            ;CHECK SIGN OF HL
+        RET P
+CHGSGN:
+        LD A,H                          ;*** CHGSGN ***
+        PUSH AF
+        CPL                             ;CHANGE SIGN OF HL
+        LD H,A
+        LD A,L
+        CPL
+        LD L,A
+        INC HL
+        POP AF
+        XOR H
+        JP P,QHOW
+        LD A,B                          ;AND ALSO FLIP B
+        XOR 80H
+        LD B,A
+        RET
+CKHLDE:
+        LD A,H                          ;SAME SIGN?
+        XOR D                           ;YES, COMPARE
+        JP P,CK1                        ;NO, XCHANGE AND COMP
+        EX DE,HL
+CK1:
+        RST 20H
+        RET
+;*************************************************************
+;
+; *** SETVAL *** FIN *** ENDCHK *** & ERROR (& FRIENDS) ***
+;
+; "SETVAL" EXPECTS A VARIABLE, FOLLOWED BY AN EQUAL SIGN AND
+; THEN AN EXPR.  IT EVALUATES THE EXPR. AND SET THE VARIABLE
+; TO THAT VALUE.
+;
+; "FIN" CHECKS THE END OF A COMMAND.  IF IT ENDED WITH ";",
+; EXECUTION CONTINUES.  IF IT ENDED WITH A CR, IT FINDS THE
+; NEXT LINE AND CONTINUE FROM THERE.
+;
+; "ENDCHK" CHECKS IF A COMMAND IS ENDED WITH CR.  THIS IS
+; REQUIRED IN CERTAIN COMMANDS.  (GOTO, RETURN, AND STOP ETC.)
+;
+; "ERROR" PRINTS THE STRING POINTED BY DE (AND ENDS WITH CR).
+; IT THEN PRINTS THE LINE POINTED BY 'CURRNT' WITH A "?"
+; INSERTED AT WHERE THE OLD TEXT POINTER (SHOULD BE ON TOP
+; OF THE STACK) POINTS TO.  EXECUTION OF TB IS STOPPED
+; AND TBI IS RESTARTED.  HOWEVER, IF 'CURRNT' -> ZERO
+; (INDICATING A DIRECT COMMAND), THE DIRECT COMMAND IS NOT
+; PRINTED.  AND IF 'CURRNT' -> NEGATIVE # (INDICATING 'INPUT'
+; COMMAND), THE INPUT LINE IS NOT PRINTED AND EXECUTION IS
+; NOT TERMINATED BUT CONTINUED AT 'INPERR'.
+;
+; RELATED TO 'ERROR' ARE THE FOLLOWING:
+; 'QWHAT' SAVES TEXT POINTER IN STACK AND GET MESSAGE "WHAT?"
+; 'AWHAT' JUST GET MESSAGE "WHAT?" AND JUMP TO 'ERROR'.
+; 'QSORRY' AND 'ASORRY' DO SAME KIND OF THING.
+; 'AHOW' AND 'AHOW' IN THE ZERO PAGE SECTION ALSO DO THIS.
+;*************************************************************
+
+SETVAL:
+        RST 38H                         ;*** SETVAL ***
+        JP C,QWHAT                      ;"WHAT?" NO VARIABLE
+        PUSH HL                         ;SAVE ADDRESS OF VAR.
+        RST 08H                         ;PASS "=" SIGN
+        DB '='
+        DB SV1-$-1
+        RST 18H                         ;EVALUATE EXPR.
+        LD B,H                          ;VALUE IS IN BC NOW
+        LD C,L
+        POP HL                          ;GET ADDRESS
+        LD (HL),C                       ;SAVE VALUE
+        INC HL
+        LD (HL),B
+        RET
+SV1:
+        JP QWHAT                        ;NO "=" SIGN
+FIN:
+        RST 08H                         ;*** FIN ***
+        DB 3BH
+        DB FI1-$-1
+        POP AF                          ;";", PURGE RET. ADDR.
+        JP RUNSML                       ;CONTINUE SAME LINE
+FI1:
+        RST 08H                         ;NOT ";", IS IT CR?
+        DB CR
+        DB FI2-$-1
+        POP AF                          ;YES, PURGE RET. ADDR.
+        JP RUNNXL                       ;RUN NEXT LINE
+FI2:
+        RET                             ;ELSE RETURN TO CALLER
+ENDCHK:
+        RST 28H                         ;*** ENDCHK ***
+        CP CR                           ;END WITH CR?
+        RET Z                           ;OK, ELSE SAY: "WHAT?"
+QWHAT:
+        PUSH DE                         ;*** QWHAT ***
+AWHAT:
+        LD DE,WHAT                      ;*** AWHAT ***
+ERROR_ROUTINE:
+        SUB A                           ;*** ERROR ***
+        CALL PRTSTG                     ;PRINT 'WHAT?', 'HOW?'
+        POP DE                          ;OR 'SORRY'
+        LD A,(DE)                       ;SAVE THE CHARACTER
+        PUSH AF                         ;AT WHERE OLD DE ->
+        SUB A                           ;AND PUT A 0 THERE
+        LD (DE),A
+        LD HL,(CURRNT)                  ;GET CURRENT LINE #
+        PUSH HL
+        LD A,(HL)                       ;CHECK THE VALUE
+        INC HL
+        OR (HL)
+        POP DE
+        JP Z,RSTART                     ;IF ZERO, JUST RESTART
+        LD A,(HL)                       ;IF NEGATIVE,
+        OR A
+        JP M,INPERR                     ;REDO INPUT
+        CALL PRTLN                      ;ELSE PRINT THE LINE
+        DEC DE                          ;UPTO WHERE THE 0 IS
+        POP AF                          ;RESTORE THE CHARACTER
+        LD (DE),A
+        LD A,3FH                        ;PRINT A "?"
+        RST 10H
+        SUB A                           ;AND THE REST OF THE
+        CALL PRTSTG                     ;LINE
+        JP RSTART                       ;THEN RESTART
+QSORRY:
+        PUSH DE                         ;*** QSORRY ***
+ASORRY:
+        LD DE,SORRY                     ;*** ASORRY ***
+        JR ERROR_ROUTINE
+;*************************************************************
+;
+; *** GETLN *** FNDLN (& FRIENDS) ***
+;
+; 'GETLN' READS A INPUT LINE INTO 'BUFFER'.  IT FIRST PROMPT
+; THE CHARACTER IN A (GIVEN BY THE CALLER), THEN IT FILLS
+; THE BUFFER AND ECHOS.  IT IGNORES LF'S AND NULLS, BUT STILL
+; ECHOS THEM BACK.  RUB-OUT IS USED TO CAUSE IT TO DELETE
+; THE LAST CHARACTER (IF THERE IS ONE), AND ALT-MOD IS USED TO
+; CAUSE IT TO DELETE THE WHOLE LINE AND START IT ALL OVER.
+; CR SIGNALS THE END OF A LINE, AND CAUSE 'GETLN' TO RETURN.
+;
+; 'FNDLN' FINDS A LINE WITH A GIVEN LINE # (IN HL) IN THE
+; TEXT SAVE AREA.  DE IS USED AS THE TEXT POINTER.  IF THE
+; LINE IS FOUND, DE WILL POINT TO THE BEGINNING OF THAT LINE
+; (I.E., THE LOW BYTE OF THE LINE #), AND FLAGS ARE NC & Z.
+; IF THAT LINE IS NOT THERE AND A LINE WITH A HIGHER LINE #
+; IS FOUND, DE POINTS TO THERE AND FLAGS ARE NC & NZ.  IF
+; WE REACHED THE END OF TEXT SAVE AREA AND CANNOT FIND THE
+; LINE, FLAGS ARE C & NZ.
+; 'FNDLN' WILL INITIALIZE DE TO THE BEGINNING OF THE TEXT SAVE
+; AREA TO START THE SEARCH.  SOME OTHER ENTRIES OF THIS
+; ROUTINE WILL NOT INITIALIZE DE AND DO THE SEARCH.
+; 'FNDLNP' WILL START WITH DE AND SEARCH FOR THE LINE #.
+; 'FNDNXT' WILL BUMP DE BY 2, FIND A CR AND THEN START SEARCH.
+; 'FNDSKP' USE DE TO FIND A CR, AND THEN START SEARCH.
+;*************************************************************
+
+GETLN:
+        RST 10H                         ;*** GETLN ***
+        LD DE,BUFFER                    ;PROMPT AND INIT.
+GL1:
+        CALL CHKIO                      ;CHECK KEYBOARD
+        JR Z,GL1                        ;NO INPUT, WAIT
+        CP 7FH                          ;DELETE LAST CHARACTER?
+        JR Z,GL3                        ;YES
+        RST 10H                         ;INPUT, ECHO BACK
+        CP 0AH                          ;IGNORE LF
+        JR Z,GL1
+        OR A                            ;IGNORE NULL
+        JR Z,GL1
+        CP 7DH                          ;DELETE THE WHOLE LINE?
+        JR Z,GL4                        ;YES
+        LD (DE),A                       ;ELSE SAVE INPUT
+        INC DE                          ;AND BUMP POINTER
+        CP 0DH                          ;WAS IT CR
+        RET Z                           ;YES, END OF LINE
+        LD A,E                          ;ELSE MORE FREE ROOM?
+        CP BUFEND & 0FFH
+        JR NZ,GL1                       ;YES, GET NEXT INPUT
+GL3:
+        LD A,E                          ;DELETE LAST CHARACTER
+        CP BUFFER & 0FFH                ;BUT DO WE HAVE ANY?
+        JR Z,GL4                        ;NO, REDO WHOLE LINE
+        DEC DE                          ;YES, BACKUP POINTER
+        LD A,5CH                        ;AND ECHO A BACK-SLASH
+        RST 10H
+        JR GL1                          ;GO GET NEXT INPUT
+GL4:
+        CALL CRLF                       ;REDO ENTIRE LINE
+        LD A,05EH                       ;CR, LF AND UP-ARROW
+        JR GETLN
+FNDLN:
+        LD A,H                          ;*** FNDLN ***
+        OR A                            ;CHECK SIGN OF HL
+        JP M,QHOW                       ;IT CANNOT BE -
+        LD DE,TXTBGN                    ;INIT TEXT POINTER
+FNDLP:                                  ;*** FDLNP ***
+FL1:
+        PUSH HL                         ;SAVE LINE #
+        LD HL,(TXTUNF)                  ;CHECK IF WE PASSED END
+        DEC HL
+        RST 20H
+        POP HL                          ;GET LINE # BACK
+        RET C                           ;C,NZ PASSED END
+        LD A,(DE)                       ;WE DID NOT, GET BYTE 1
+        SUB L                           ;IS THIS THE LINE?
+        LD B,A                          ;COMPARE LOW ORDER
+        INC DE
+        LD A,(DE)                       ;GET BYTE 2
+        SBC A,H                         ;COMPARE HIGH ORDER
+        JR C,FL2                        ;NO, NOT THERE YET
+        DEC DE                          ;ELSE WE EITHER FOUND
+        OR B                            ;IT, OR IT IS NOT THERE
+        RET                             ;NC,Z;FOUND, NC,NZ:NO
+FNDNXT:                                 ;*** FNDNXT ***
+        INC DE                          ;FIND NEXT LINE
+FL2:
+        INC DE                          ;JUST PASSED BYTE 1 & 2
+FNDSKP:
+        LD A,(DE)                       ;*** FNDSKP ***
+        CP CR                           ;TRY TO FIND CR
+        JR NZ,FL2                       ;KEEP LOOKING
+        INC DE                          ;FOUND CR, SKIP OVER
+        JR FL1                          ;CHECK IF END OF TEXT
+;*************************************************************
+;
+; *** PRTSTG *** QTSTG *** PRTNUM *** & PRTLN ***
+;
+; 'PRTSTG' PRINTS A STRING POINTED BY DE.  IT STOPS PRINTING
+; AND RETURNS TO CALLER WHEN EITHER A CR IS PRINTED OR WHEN
+; THE NEXT BYTE IS THE SAME AS WHAT WAS IN A (GIVEN BY THE
+; CALLER).  OLD A IS STORED IN B, OLD B IS LOST.
+;
+; 'QTSTG' LOOKS FOR A BACK-ARROW, SINGLE QUOTE, OR DOUBLE
+; QUOTE.  IF NONE OF THESE, RETURN TO CALLER.  IF BACK-ARROW,
+; OUTPUT A CR WITHOUT A LF.  IF SINGLE OR DOUBLE QUOTE, PRINT
+; THE STRING IN THE QUOTE AND DEMANDS A MATCHING UNQUOTE.
+; AFTER THE PRINTING THE NEXT 3 BYTES OF THE CALLER IS SKIPPED
+; OVER (USUALLY A JUMP INSTRUCTION.
+;
+; 'PRTNUM' PRINTS THE NUMBER IN HL.  LEADING BLANKS ARE ADDED
+; IF NEEDED TO PAD THE NUMBER OF SPACES TO THE NUMBER IN C.
+; HOWEVER, IF THE NUMBER OF DIGITS IS LARGER THAN THE # IN
+; C, ALL DIGITS ARE PRINTED ANYWAY.  NEGATIVE SIGN IS ALSO
+; PRINTED AND COUNTED IN, POSITIVE SIGN IS NOT.
+;
+; 'PRTLN' PRINTS A SAVED TEXT LINE WITH LINE # AND ALL.
+;*************************************************************
+
+PRTSTG:
+        LD B,A                          ;*** PRTSTG ***
+PS1:
+        LD A,(DE)                       ;GET A CHARACTER
+        INC DE                          ;BUMP POINTER
+        CP B                            ;SAME AS OLD A?
+        RET Z                           ;YES, RETURN
+        RST 10H                         ;NO, NEXT
+        CP CR                           ;WAS IT A CR?
+        JR NZ,PS1                       ;NO, NEXT
+        RET                             ;YES, RETURN
+QTSTG:
+        RST 08H                         ;*** QTSTG ***
+        DB '"'
+        DB QT3-$-1
+        LD A,22H                        ;IT IS A "
+QT1:
+        CALL PRTSTG                     ;PRINT UNTIL ANOTHER
+        CP CR                           ;WAS LAST ONE A CR?
+        POP HL                          ;RETURN ADDRESS
+        JP Z,RUNNXL                     ;WAS CR, RUN NEXT LINE
+QT2:
+        INC HL                          ;SKIP 3 BYTES ON RETURN
+        INC HL
+        INC HL
+        JP (HL)                         ;RETURN
+QT3:
+        RST 08H                         ;IS IT A '?
+        DB 27H
+        DB QT4-$-1
+        LD A,27H                        ;YES, DO THE SAME
+        JR QT1                          ;AS IN "
+QT4:
+        RST 08H                         ;IS IT BACK-ARROW?
+        DB 5FH
+        DB QT5-$-1
+        LD A,8DH                        ;YES, CR WITHOUT LF
+        RST 10H                         ;DO IT TWICE TO GIVE
+        RST 10H                         ;TTY ENOUGH TIME
+        POP HL                          ;RETURN ADDRESS
+        JR QT2
+QT5:
+        RET                             ;NONE OF ABOVE
+;
+PRTNUM:
+        LD B,00H                        ;*** PRTNUM ***
+        CALL CHKSGN                     ;CHECK SIGN
+        JP P,PN1                        ;NO SIGN
+        LD B,'-'                        ;B=SIGN
+        DEC C                           ;'-' TAKES SPACE
+PN1:
+        PUSH DE                         ;SAVE
+        LD DE,000AH                     ;DECIMAL
+        PUSH DE                         ;SAVE AS FLAG
+        DEC C                           ;C=SPACES
+        PUSH BC                         ;SAVE SIGN & SPACE
+PN2:
+        CALL DIVIDE                     ;DIVIDE HL BY 10
+        LD A,B                          ;RESULT 0?
+        OR C
+        JR Z,PN3                        ;YES, WE GOT ALL
+        EX (SP),HL                      ;NO, SAVE REMAINDER
+        DEC L                           ;AND COUNT SPACE
+        PUSH HL                         ;HL IS OLD BC
+        LD H,B                          ;MOVE RESULT TO BC
+        LD L,C
+        JR PN2                          ;AND DIVIDE BY 10
+PN3:
+        POP BC                          ;WE GOT ALL DIGITS IN
+PN4:
+        DEC C                           ;THE STACK
+        LD A,C                          ;LOOK AT SPACE COUNT
+        OR A
+        JP M,PN5                        ;NO LEADING BLANKS
+        LD A,20H                        ;LEADING BLANKS
+        RST 10H
+        JR PN4                          ;MORE?
+PN5:
+        LD A,B                          ;PRINT SIGN
+        OR A
+        CALL NZ,0010H
+        LD E,L                          ;LAST REMAINDER IN E
+PN6:
+        LD A,E                          ;CHECK DIGIT IN E
+        CP 0AH                          ;10 IS FLAG FOR NO MORE
+        POP DE
+        RET Z                           ;IF SO, RETURN
+        ADD A,30H                       ;ELSE, CONVERT TO ASCII
+        RST 10H                         ;PRINT THE DIGIT
+        JR PN6                          ;GO BACK FOR MORE
+PRTLN:
+        LD A,(DE)                       ;*** PRTLN ***
+        LD L,A                          ;LOW ORDER LINE #
+        INC DE
+        LD A,(DE)                       ;HIGH ORDER
+        LD H,A
+        INC DE
+        LD C,04H                        ;PRINT 4 DIGIT LINE #
+        CALL PRTNUM
+        LD A,20H                        ;FOLLOWED BY A BLANK
+        RST 10H
+        SUB A                           ;AND THEN THE NEXT
+        CALL PRTSTG
+        RET
+;*************************************************************
+;
+; *** MVUP *** MVDOWN *** POPA *** & PUSHA ***
+;
+; 'MVUP' MOVES A BLOCK UP FROM WHERE DE-> TO WHERE BC-> UNTIL
+; DE = HL
+;
+; 'MVDOWN' MOVES A BLOCK DOWN FROM WHERE DE-> TO WHERE HL->
+; UNTIL DE = BC
+;
+; 'POPA' RESTORES THE 'FOR' LOOP VARIABLE SAVE AREA FROM THE
+; STACK
+;
+; 'PUSHA' STACKS THE 'FOR' LOOP VARIABLE SAVE AREA INTO THE
+; STACK
+;*************************************************************
+
+MVUP:
+        RST 20H                         ;*** MVUP ***
+        RET Z                           ;DE = HL, RETURN
+        LD A,(DE)                       ;GET ONE BYTE
+        LD (BC),A                       ;MOVE IT
+        INC DE                          ;INCREASE BOTH POINTERS
+        INC BC
+        JR MVUP                         ;UNTIL DONE
+MVDOWN:
+        LD A,B                          ;*** MVDOWN ***
+        SUB D                           ;TEST IF DE = BC
+        JP NZ,MD1                       ;NO, GO MOVE
+        LD A,C                          ;MAYBE, OTHER BYTE?
+        SUB E
+        RET Z                           ;YES, RETURN
+MD1:
+        DEC DE                          ;ELSE MOVE A BYTE
+        DEC HL                          ;BUT FIRST DECREASE
+        LD A,(DE)                       ;BOTH POINTERS AND
+        LD (HL),A                       ;THEN DO IT
+        JR MVDOWN                       ;LOOP BACK
+POPA:
+        POP BC                          ;BC = RETURN ADDR.
+        POP HL                          ;RESTORE LOPVAR, BUT
+        LD (LOPVAR),HL                  ;=0 MEANS NO MORE
+        LD A,H
+        OR L
+        JR Z,PP1                        ;YEP, GO RETURN
+        POP HL                          ;NOP, RESTORE OTHERS
+        LD (LOPINC),HL
+        POP HL
+        LD (LOPLMT),HL
+        POP HL
+        LD (LOPLN),HL
+        POP HL
+        LD (LOPPT),HL
+PP1:
+        PUSH BC                         ;BC = RETURN ADDR.
+        RET
+PUSHA:
+        LD HL,STKLMT                    ;*** PUSHA ***
+        CALL CHGSGN
+        POP BC                          ;BC=RETURN ADDRESS
+        ADD HL,SP                       ;IS STACK NEAR THE TOP?
+        JP NC,QSORRY                    ;YES, SORRY FOR THAT
+        LD HL,(LOPVAR)                  ;ELSE SAVE LOOP VAR'S
+        LD A,H                          ;BUT IF LOPVAR IS 0
+        OR L                            ;THAT WILL BE ALL
+        JR Z,PU1
+        LD HL,(LOPPT)                   ;ELSE, MORE TO SAVE
+        PUSH HL
+        LD HL,(LOPLN)
+        PUSH HL
+        LD HL,(LOPLMT)
+        PUSH HL
+        LD HL,(LOPINC)
+        PUSH HL
+        LD HL,(LOPVAR)
+PU1:
+        PUSH HL
+        PUSH BC                         ;BC = RETURN ADDR.
+        RET
+;*************************************************************
+;
+; *** OUTC *** & CHKIO ***
+;
+; THESE ARE THE ONLY I/O ROUTINES IN TBI.
+; 'OUTC' IS CONTROLLED BY A SOFTWARE SWITCH 'OCSW'.  IF OCSW=0
+; 'OUTC' WILL JUST RETURN TO THE CALLER.  IF OCSW IS NOT 0,
+; IT WILL OUTPUT THE BYTE IN A.  IF THAT IS A CR, A LF IS ALSO
+; SEND OUT.  ONLY THE FLAGS MAY BE CHANGED AT RETURN. ALL REG.
+; ARE RESTORED.
+;
+; 'CHKIO' CHECKS THE INPUT.  IF NO INPUT, IT WILL RETURN TO
+; THE CALLER WITH THE Z FLAG SET.  IF THERE IS INPUT, Z FLAG
+; IS CLEARED AND THE INPUT BYTE IS IN A.  HOWEVER, IF THE
+; INPUT IS A CONTROL-O, THE 'OCSW' SWITCH IS COMPLIMENTED, AND
+; Z FLAG IS RETURNED.  IF A CONTROL-C IS READ, 'CHKIO' WILL
+; RESTART TBI AND DO NOT RETURN TO THE CALLER.
+;
+; Do not modify these routines.  Routines requiring
+; modification are : SERIAL_INIT, RX_RDY, and TX_RDY.
+;*************************************************************
+
+INIT:
+        DI
+        CALL SERIAL_INIT        ;INITIALIZE THE SIO
+        LD D,19H
+PATLOP:
+        CALL CRLF
+        DEC D
+        JR NZ,PATLOP
+        SUB A
+        LD DE,MSG1          ;PRINT THE BOOT MESSAGES
+        CALL PRTSTG
+        LD DE,MSG2
+        CALL PRTSTG
+        LD HL,START
+        LD (RANPNT),HL
+        LD HL,TXTBGN
+        LD (TXTUNF),HL
+        JP RSTART
+OUTC:
+        JR NZ,OUTC2         ;IT IS ON
+        POP AF                          ;IT IS OFF
+        RET                             ;RESTORE AF AND RETURN
+OUTC2:
+        CALL TX_RDY         ;SEE IF TRANSMIT IS AVAILABLE
+        POP AF                          ;RESTORE THE REGISTER
+        OUT (SerialPort),A      ;SEND THE BYTE
+        CP CR
+        RET NZ
+        LD A,LF
+        RST 10H
+        LD A,CR
+        RET
+CHKIO:
+        CALL RX_RDY         ;CHECK IF CHARACTER AVAILABLE
+        RET Z                           ;RETURN IF NO CHARACTER AVAILABLE
+
+        PUSH BC                         ;IF IT'S A LF, IGNORE AND RETURN
+        LD B,A                          ; AS IF THERE WAS NO CHARACTER.
+        SUB LF
+        JR Z,CHKIO2
+        LD A,B                          ;OTHERWISE RESTORE 'A' AND 'BC'
+        POP BC                          ; AND CONTINUE ON.
+
+        CP 0FH                          ;IS IT CONTROL-0?
+        JR NZ,CI1                       ;NO, MORE CHECKING
+        LD A,(OCSW)                     ;CONTROL-0 FLIPS OCSW
+        CPL                             ;ON TO OFF, OFF TO ON
+        LD (OCSW),A
+        JR CHKIO                        ;GET ANOTHER INPUT
+CHKIO2:
+        LD A,00H                        ;CLEAR A
+        OR A                            ;ZET THE Z-FLAG
+        POP BC                          ;RESTORE THE 'BC' PAIR
+        RET                             ;RETURN WITH 'Z' SET.
+CI1:
+        CP 03H                          ;IS IT CONTROL-C?
+        RET NZ                          ;NO, RETURN "NZ"
+        JP RSTART                       ;YES, RESTART TBI
+
+
+MSG1:   DB   ESC,"[2J",ESC,"[H"         ;SCREEN CLEAR
+        DB   'Z80 TINY BASIC 2.0g',CR       ;BOOT MESSAGE
+MSG2:   DB   'PORTED BY DOUG GABBARD, 2017',CR
+
+;*************************************************************
+;
+; *** TABLES *** DIRECT *** & EXEC ***
+;
+; THIS SECTION OF THE CODE TESTS A STRING AGAINST A TABLE.
+; WHEN A MATCH IS FOUND, CONTROL IS TRANSFERED TO THE SECTION
+; OF CODE ACCORDING TO THE TABLE.
+;
+; AT 'EXEC', DE SHOULD POINT TO THE STRING AND HL SHOULD POINT
+; TO THE TABLE-1.  AT 'DIRECT', DE SHOULD POINT TO THE STRING.
+; HL WILL BE SET UP TO POINT TO TAB1-1, WHICH IS THE TABLE OF
+; ALL DIRECT AND STATEMENT COMMANDS.
+;
+; A '.' IN THE STRING WILL TERMINATE THE TEST AND THE PARTIAL
+; MATCH WILL BE CONSIDERED AS A MATCH.  E.G., 'P.', 'PR.',
+; 'PRI.', 'PRIN.', OR 'PRINT' WILL ALL MATCH 'PRINT'.
+;
+; THE TABLE CONSISTS OF ANY NUMBER OF ITEMS.  EACH ITEM
+; IS A STRING OF CHARACTERS WITH BIT 7 SET TO 0 AND
+; A JUMP ADDRESS STORED HI-LOW WITH BIT 7 OF THE HIGH
+; BYTE SET TO 1.
+;
+; END OF TABLE IS AN ITEM WITH A JUMP ADDRESS ONLY.  IF THE
+; STRING DOES NOT MATCH ANY OF THE OTHER ITEMS, IT WILL
+; MATCH THIS NULL ITEM AS DEFAULT.
+;*************************************************************
+
+TAB1:                                   ;DIRECT COMMANDS
+        DB 'LIST'
+        DWA LIST
+        DB 'RUN'
+        DWA RUN
+        DB 'NEW'
+        DWA NEW
+TAB2:                                   ;DIRECT/STATEMENT
+        DB 'NEXT'
+        DWA NEXT
+        DB 'LET'
+        DWA LET
+        DB 'IF'
+        DWA IFF
+        DB 'GOTO'
+        DWA GOTO
+        DB 'GOSUB'
+        DWA GOSUB
+        DB 'RETURN'
+        DWA RETURN
+        DB 'REM'
+        DWA REM
+        DB 'FOR'
+        DWA FOR
+        DB 'INPUT'
+        DWA INPUT
+        DB 'PRINT'
+        DWA PRINT
+        DB 'STOP'
+        DWA STOP
+        DWA DEFLT
+TAB4:                                   ;FUNCTIONS
+        DB 'RND'
+        DWA RND
+        DB 'ABS'
+        DWA ABS
+        DB 'SIZE'
+        DWA SIZE
+        DWA XP40
+TAB5:                                   ;"TO" IN "FOR"
+        DB 'TO'
+        DWA FR1
+        DWA QWHAT
+TAB6:                                   ;"STEP" IN "FOR"
+        DB 'STEP'
+        DWA FR2
+        DWA FR3
+TAB8:                                   ;RELATION OPERATORS
+        DB '>='
+        DWA XP11
+        DB '#'
+        DWA XP12
+        DB '>'
+        DWA XP13
+        DB '='
+        DWA XP15
+        DB '<='
+        DWA XP14
+        DB '<'
+        DWA XP16
+        DWA XP17
+DIRECT: LD HL,TAB1-1                   ;*** DIRECT ***
+EXEC:                                   ;*** EXEC ***
+EX0:    RST 28H                         ;IGNORE LEADING BLANKS
+        PUSH DE                         ;SAVE POINTER
+EX1:
+        LD A,(DE)                       ;IF FOUND '.' IN STRING
+        INC DE                          ;BEFORE ANY MISMATCH
+        CP 23H                          ;WE DECLARE A MATCH
+        JR Z,EX3
+        INC HL                          ;HL->TABLE
+        CP (HL)                         ;IF MATCH, TEST NEXT
+        JR Z,EX1
+        LD A,7FH                        ;ELSE SEE IF BIT 7
+        DEC DE                          ;OF TABLE IS SET, WHICH
+        CP (HL)                         ;IS THE JUMP ADDR. (HI)
+        JR C,EX5                        ;C:YES, MATCHED
+EX2:
+        INC HL                          ;NC:NO, FIND JUMP ADDR.
+        CP (HL)
+        JR NC,EX2
+        INC HL                          ;BUMP TO NEXT TAB. ITEM
+        POP DE                          ;RESTORE STRING POINTER
+        JR EX0                          ;TEST AGAINST NEXT ITEM
+EX3:
+        LD A,7FH                        ;PARTIAL MATCH, FIND
+EX4:
+        INC HL                          ;JUMP ADDR., WHICH IS
+        CP (HL)                         ;FLAGGED BY BIT 7
+        JR NC,EX4
+EX5:
+        LD A,(HL)                       ;LOAD HL WITH THE JUMP
+        INC HL                          ;ADDRESS FROM THE TABLE
+        LD L,(HL)
+        AND 7FH                         ;MASK OFF BIT 7
+        LD H,A
+        POP AF                          ;CLEAN UP THE GABAGE
+        JP (HL)                         ;AND WE GO DO IT
+;-------------------------------------------------------------------------------
+;///////////////////////////////////////////////////////////////////////////////
+;-------------------------------------------------------------------------------
+;COMPUTER SPECIFIC ROUTINES.
+;-------------------------------------------------------------------------------
+SERIAL_INIT:
+
+    ; This routine is for initializing your serial port.
+
+        RET
+;-------------------------------------------------------------------------------
+TX_RDY:
+    ; This routine is checking if the Serial Port is ready to send
+    ; a character.
+    IN A,(0F1h)
+    AND 1
+    JP NZ,TX_RDY
+    RET
+        
+;-------------------------------------------------------------------------------
+RX_RDY:
+
+    ; This routine is for checking if a character is available over
+    ; serial. If a character is available, it returns to the calling
+    ; function with the character in 'A' and the Z-flag reset.
+    ; However, if a character is not available, it returns with the
+    ; Z-flag set.
+
+        RET
+;-------------------------------------------------------------------------------
+;///////////////////////////////////////////////////////////////////////////////
+;-------------------------------------------------------------------------------
+
+LSTROM:                                 ;ALL ABOVE CAN BE ROM
+                    ;HERE DOWN MUST BE RAM
+        ORG  08000H
+        ORG  08700H ; Last 256 bytes of RAM
+VARBGN: DS   55                         ;VARIABLE @(0)
+BUFFER: DS   64                         ;INPUT BUFFER
+BUFEND: DS   1                          ;BUFFER ENDS
+STKLMT: DS   1                          ;TOP LIMIT FOR STACK
+        END

snapshots/jotego_jtcores_pr1087/modules/jtframe/cfg/sound/jtframe_jt49_filters.yaml

@@ -0,0 +1,6 @@
+jtframe:
+  - from: sound
+    get:
+    - jtframe_jt49_filters.v
+    - jtframe_fir.v
+    - jtframe_dcrm.v

snapshots/jotego_jtcores_pr1087/modules/jtframe/cfg/video/jtframe_obj.yaml

@@ -0,0 +1,11 @@
+jtframe:
+  - from: video
+    get:
+      - jtframe_draw.v
+      - jtframe_objscan.v
+      - jtframe_objdraw.v
+      - jtframe_objdraw_trunc.v
+      - jtframe_objdraw_gate.v
+  - from: ram
+    get:
+      - jtframe_obj_buffer.v

snapshots/jotego_jtcores_pr1087/modules/jtframe/cfg/video/jtframe_scroll.yaml

@@ -0,0 +1,6 @@
+jtframe:
+  - from: video/tilemap
+    get:
+      - jtframe_scroll.v
+      - jtframe_scroll_offset.v
+      - jtframe_tilemap.v

snapshots/jotego_jtcores_pr1087/modules/jtframe/doc/cheat/cheatasm

@@ -0,0 +1,2 @@
+#!/bin/bash
+opbasm -6 -x -m 1024 $*

snapshots/jotego_jtcores_pr1087/modules/jtframe/doc/cheat/cheatzip

@@ -0,0 +1,7 @@
+#!/bin/bash
+FILE=$(basename $1 .s)
+opbasm -6 -x -m 1024 $FILE.s || exit $?
+pico2hex $FILE.hex
+zip cheat.zip $FILE.bin || exit $?
+sshpass -p 1 scp cheat.zip root@MiSTer.home:/media/fat/games/mame
+

snapshots/jotego_jtcores_pr1087/modules/jtframe/doc/cheat/ecofghtr.s

@@ -0,0 +1,126 @@
+; use "cheatzip" script to assemble and send to MiSTer
+
+; The LED will blink if the cheat bits 7:0 are enabled
+; CPSx work RAM offset = 30'0000h
+
+; Register use
+; SA = frame counter
+; SB = LED
+
+    ; enable interrupt
+    load sa,0   ; SA = frame counter, modulo 60
+    load sb,0
+BEGIN:
+    output s0,0x40
+
+    ; Detect blanking
+    input s0,0x80
+    and   s0,0x20;   test for blanking
+    jump z,inblank
+    jump notblank
+inblank:
+    fetch s1,0
+    test s1,0x20
+    jump z,notblank
+    store s0,0  ; stores last LVBL
+    call ISR ; do blank procedure
+    jump BEGIN
+notblank:
+    store s0,0
+    jump BEGIN
+
+ISR:
+    input sf,0x10
+    test sf,0xff
+    jump z,.nothing
+
+    compare sa,0
+    jump nz,PARSE_FLAGS
+    ; invert LED signal
+    add sb,1
+    jump PARSE_FLAGS
+.nothing:
+    load sb,0      ; turn off LED
+    jump CLOSE_FRAME
+
+PARSE_FLAGS:
+    ; interrupt routine
+    input sf,0x10
+    test  sf,1      ; bit 0
+    jump Z,TEST_FLAG1
+    ; Infinite Credits
+    ; FF02E8=09 -> (02E8/2+30'0000) = 300174
+    load  s0,0x74
+    load  s1,0x01
+    load  s2,0x30
+    load  s3,0
+    load  s4,9
+    load  s5,1
+    call  WRITE_SDRAM
+
+TEST_FLAG1:
+    input sf,0x10
+    test  sf,2      ; bit 1
+    jump Z,TEST_FLAG2
+    ; Infinite Lives
+    ; FFF5F2=09  -> (F5F2/2+30'0000) = 307AF9
+    load  s0,0xf9
+    load  s1,0x7A
+    load  s2,0x30
+    load  s3,0
+    load  s4,9
+    load  s5,1
+    call  WRITE_SDRAM
+
+TEST_FLAG2:
+    input sf,0x10
+    test  sf,4      ; bit 1
+    jump Z,TEST_FLAG3
+    ; Invincibility
+    ; FF877A=FF -> 3043BD once per second
+    compare sa,0
+    jump nz,TEST_FLAG3
+    load  s0,0xBD
+    load  s1,0x43
+    load  s2,0x30
+    load  s3,0
+    load  s4,0xff
+    load  s5,1
+    call  WRITE_SDRAM
+
+TEST_FLAG3:
+CLOSE_FRAME:
+    output sb,6     ; LED
+    ; Frame counter
+    add sa,1
+    compare sa,59'd
+    jump nz,.else
+    load sa,0
+.else:
+    return
+    ;returni ENABLE
+
+    ; SDRAM address in s2-s0
+    ; SDRAM data out in s4-s3
+    ; SDRAM data mask in s5
+    ; Modifies sf
+WRITE_SDRAM:
+    output s5, 5
+    output s4, 4
+    output s3, 3
+    output s2, 2
+    output s1, 1
+    output s0, 0
+    output s1, 0xC0   ; s1 value doesn't matter
+.loop:
+    input  sf, 0x80
+    compare sf, 0xC0
+    return z
+    jump .loop
+
+default_jump fatal_error
+fatal_error:
+    jump fatal_error
+
+    address 3FF    ; interrupt vector
+    jump ISR

snapshots/jotego_jtcores_pr1087/modules/jtframe/doc/cheat/ghouls.s

@@ -0,0 +1,173 @@
+; use "cheatzip" script to assemble and send to MiSTer
+
+; The LED will blink if the cheat bits 7:0 are enabled
+; CPSx work RAM offset = 30'0000h
+
+; Register use
+; SA = frame counter
+; SB = LED
+
+    ; enable interrupt
+    load sa,0   ; SA = frame counter, modulo 60
+    load sb,0
+    call CLS
+BEGIN:
+    output s0,0x40
+
+    ; Detect blanking
+    input s0,0x80
+    and   s0,0x20;   test for blanking
+    jump z,inblank
+    jump notblank
+inblank:
+    fetch s1,0
+    test s1,0x20
+    jump z,notblank
+    store s0,0  ; stores last LVBL
+    call ISR ; do blank procedure
+    jump BEGIN
+notblank:
+    store s0,0
+    jump BEGIN
+
+ISR:
+    input sf,0x10
+    test sf,0xff
+    jump z,.nothing
+
+    compare sa,0
+    jump nz,PARSE_FLAGS
+    ; invert LED signal
+    add sb,1
+    jump PARSE_FLAGS
+.nothing:
+    load sb,0      ; turn off LED
+    load s0,0      ; disable screen display
+    output s0,0xa
+    jump SCREEN
+
+PARSE_FLAGS:
+    ; enable screen display
+    load s0,1
+    output s0,0xa
+
+    input sf,0x10
+    and   sf,7      ; bits 2:0
+    jump Z,SCREEN
+    ; P1 weapon selection
+    ; FF07C6=weapon  -> (7C6/2+30'0000) = 3003e3
+    load  s0,0xe3
+    load  s1,0x03
+    load  s2,0x30
+    load  s3,0
+    load  s4,sf
+    sub   s4,1  ; weapon code starts from 0
+    load  s5,1
+    call  WRITE_SDRAM
+
+SCREEN:
+    ; Show the number of lives
+    ; FF07AD -> 3003d6 (MSB)
+    load  s0,0xd6
+    load  s1,0x03
+    load  s2,0x30
+    call  READ_SDRAM
+    load  s0,0x44
+    load  s1,s7
+    call WRITE_HEX
+    load  s1,s6
+    call WRITE_HEX
+
+CLOSE_FRAME:
+    output sb,6     ; LED
+    ; Frame counter
+    add sa,1
+    compare sa,59'd
+    jump nz,.else
+    load sa,0
+.else:
+    return
+    ;returni ENABLE
+
+    ; s0 screen address
+    ; s1 number to write
+    ; modifies s2
+    ; s0 updated to point to the next column
+WRITE_HEX:
+    output s0,8
+    load s2,s1
+    sr0 s2
+    sr0 s2
+    sr0 s2
+    sr0 s2
+    call WRITE_HEX4
+    add s0,1
+    output s0,8
+    load s2,s1
+    call WRITE_HEX4
+    add s0,1    ; leave the cursor at the next column
+    return
+
+    ; s2 number to write
+    ; modifies s2
+WRITE_HEX4:
+    and s2,f
+    compare s2,a
+    jump nc,.over10
+    jump z,.over10
+    add s2,16'd
+    jump .write
+.over10:
+    add s2,23'd
+.write:
+    output s2,9
+    return
+
+CLS:
+    load s0,0
+    load s1,0
+.loop:
+    output s0,8
+    output s1,9
+    add s0,1
+    jump nc,.loop
+
+    ; SDRAM address in s2-s0
+    ; SDRAM data out in s4-s3
+    ; SDRAM data mask in s5
+    ; Modifies sf
+WRITE_SDRAM:
+    output s5, 5
+    output s4, 4
+    output s3, 3
+    output s2, 2
+    output s1, 1
+    output s0, 0
+    output s1, 0xC0   ; s1 value doesn't matter
+.loop:
+    input  sf, 0x80
+    compare sf, 0xC0
+    return z
+    jump .loop
+
+    ; Modifies sf
+    ; Read data in s7,s6
+READ_SDRAM:
+    output s2, 2
+    output s1, 1
+    output s0, 0
+    output s1, 0x80   ; s1 value doesn't matter
+.loop:
+    input  sf, 0x80
+    compare sf, 0xC0
+    jump nz,.loop
+    input s6,6
+    input s7,7
+    return
+
+default_jump fatal_error
+fatal_error:
+    jump fatal_error
+
+    address 3FF    ; interrupt vector
+    jump ISR

snapshots/jotego_jtcores_pr1087/modules/jtframe/doc/cheat/led.s

@@ -0,0 +1,63 @@
+    load sa,0   ; SA = frame counter, modulo 60
+    load sb,0   ; SB = LED
+BEGIN:
+    output s0,0x40
+
+    ; Detect blanking
+    input s0,0x80
+    and   s0,0x20;   test for blanking
+    jump z,inblank
+    jump notblank
+inblank:
+    fetch s1,0
+    test s1,0x20
+    jump z,notblank
+    store s0,0  ; stores last LVBL
+    call ISR ; do blank procedure
+    jump BEGIN
+notblank:
+    store s0,0
+    jump BEGIN
+
+ISR:
+    ; interrupt routine
+    compare sa,59'd
+    jump nz,.not59
+    ; invert LED signal
+    add sb,1
+    output sb,6
+.not59:
+
+    ; Frame counter
+    add sa,1
+    compare sa,60'd
+    jump nz,.else
+    load sa,0
+.else:
+    return
+    ;returni ENABLE
+
+    ; SDRAM address in s2-s0
+    ; SDRAM data out in s4-s3
+    ; SDRAM data mask in s5
+    ; Modifies sf
+WRITE_SDRAM:
+    output s5, 5
+    output s4, 4
+    output s3, 3
+    output s2, 2
+    output s1, 1
+    output s0, 0
+    output s1, 0xC0   ; s1 value doesn't matter
+.loop:
+    input  sf, 0x80
+    compare sf, 0xC0
+    return z
+    jump .loop
+
+default_jump fatal_error
+fatal_error:
+    jump fatal_error
+
+    address 3FF    ; interrupt vector
+    jump ISR

snapshots/jotego_jtcores_pr1087/modules/jtframe/doc/cheat/sf2hf.s

@@ -0,0 +1,126 @@
+; use "cheatzip" script to assemble and send to MiSTer
+
+; The LED will blink if the cheat bits 7:0 are enabled
+; CPSx work RAM offset = 30'0000h
+
+; Register use
+; SA = frame counter
+; SB = LED
+
+    enable interrupt
+    load sa,0   ; SA = frame counter, modulo 60
+    load sb,0
+BEGIN:
+    output s0,0x40  ; watchdog
+    jump BEGIN
+
+ISR:
+    input sf,0x10
+    test sf,0xff
+    jump z,.nothing
+
+    compare sa,0
+    jump nz,PARSE_FLAGS
+    ; invert LED signal
+    add sb,1
+    jump PARSE_FLAGS
+.nothing:
+    load sb,0      ; turn off LED
+    jump CLOSE_FRAME
+
+PARSE_FLAGS:
+    ; interrupt routine
+    input sf,0x10
+    test  sf,1      ; bit 0
+    jump Z,TEST_FLAG1
+    ; Infinite Time
+    ; Read FF8AC2 => 304561 and check that its zero
+    load  s0,0x61
+    load  s1,0x45
+    load  s2,0x30
+    call  READ_SDRAM
+    compare s7,0
+    jump nz,char_select
+    ; Read FF8Abe => 30455f and check that its greater than one
+    load  s0,0x5f
+    load  s1,0x45
+    load  s2,0x30
+    call  READ_SDRAM
+    compare s7,1
+    jump z,char_select  ; zero flag set, so the value was equal to 1
+    jump c,char_select  ; carry flag set, so the value was below 1
+
+    ; FF8ABE=9928 -> (8ABE/2+30'0000) = 30455F (round time)
+    load  s0,0x5F
+    load  s1,0x45
+    load  s2,0x30
+    load  s3,99 ; For M68000, the upper byte goes in s3
+    load  s4,28
+    load  s5,0
+    call  WRITE_SDRAM
+
+char_select:
+    ; always write this value
+    ; FFDDA2=203C -> (DDA2/2+30'0000) = 306ED1 (char select time)
+    load  s0,0xD1
+    load  s1,0x6E
+    load  s2,0x30
+    load  s3,20
+    load  s4,3C
+    load  s5,0
+    call  WRITE_SDRAM
+
+TEST_FLAG1:
+
+TEST_FLAG2:
+
+TEST_FLAG3:
+CLOSE_FRAME:
+    output sb,6     ; LED
+    ; Frame counter
+    add sa,1
+    compare sa,59'd
+    jump nz,.else
+    load sa,0
+.else:
+    returni ENABLE
+
+    ; SDRAM address in s2-s0
+    ; SDRAM data out in s4-s3
+    ; SDRAM data mask in s5
+    ; Modifies sf
+WRITE_SDRAM:
+    output s5, 5
+    output s4, 4
+    output s3, 3
+    output s2, 2
+    output s1, 1
+    output s0, 0
+    output s1, 0xC0   ; s1 value doesn't matter
+.loop:
+    input  sf, 0x80
+    compare sf, 0xC0
+    return z
+    jump .loop
+
+    ; Modifies sf
+    ; Read data in s7,s6
+READ_SDRAM:
+    output s2, 2
+    output s1, 1
+    output s0, 0
+    output s1, 0x80   ; s1 value doesn't matter
+.loop:
+    input  sf, 0x80
+    compare sf, 0xC0
+    jump nz,.loop
+    input s6,6
+    input s7,7
+    return
+
+default_jump fatal_error
+fatal_error:
+    jump fatal_error
+
+    address 3FF    ; interrupt vector
+    jump ISR

snapshots/jotego_jtcores_pr1087/modules/jtframe/hdl/keyboard/jtframe_mouse.v

@@ -0,0 +1,127 @@
+/*  This file is part of JTFRAME.
+    JTFRAME program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    JTFRAME program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with JTFRAME. If not, see <http://www.gnu.org/licenses/>.
+
+    Author: Jose Tejada Gomez. Twitter: @topapate
+    Version: 1.0
+    Date: 22-6-2022 */
+
+module jtframe_mouse(
+    input              rst,
+    input              clk,
+    input              lock,
+
+    // real mouse inputs
+    input signed [8:0] mouse_dx,
+    input signed [8:0] mouse_dy,
+    input        [7:0] mouse_f,     // flags (2:0 = buttons)
+    input              mouse_st,    // strobe
+    input              mouse_idx,   // up to two mouse devices
+    // Mouse emulation
+    input       [ 3:0] joyn1,       // active low
+    input       [ 3:0] joyn2,
+
+    // { 8-bit dx, 8-bit dy } encoded for the core
+    // in 2's complement unless JTFRAME_MOUSE_NO2COMPL is defined
+    output reg  [15:0] mouse_1p,
+    output reg  [15:0] mouse_2p,
+    output reg   [1:0] mouse_strobe,
+
+    output reg  [ 2:0] but_1p,
+    output reg  [ 2:0] but_2p
+);
+
+reg  [3:0] joy1_l, joy2_l;
+wire [3:0] joy1,   joy2,
+           joy1_on, joy1_off, joy2_on, joy2_off;
+
+`ifndef JTFRAME_MOUSE_NOEMU
+    `ifndef JTFRAME_LIGHTGUN
+        localparam MOUSE_EMU=1;
+    `else
+        localparam MOUSE_EMU=0;
+    `endif
+`else
+    localparam MOUSE_EMU=0;
+`endif
+
+`ifndef JTFRAME_MOUSE_EMUSENS
+    localparam [8:0] MOUSE_EMU_SENS=9'h10;
+`else
+    localparam [8:0] MOUSE_EMU_SENS=`JTFRAME_MOUSE_EMUSENS;
+`endif
+
+function [7:0] cv( input [8:0] min ); // convert to the right format
+    `ifdef JTFRAME_MOUSE_NO2COMPL
+        // some games cannot handle 2's complement, so
+        // a conversion to sign plus magnitude is provided here
+        cv = { min[8], min[8] ? -min[7:1] : min[7:1] };
+    `else
+        cv = min[8:1];
+    `endif
+endfunction
+
+assign joy1     = ~joyn1,
+       joy2     = ~joyn2;
+assign joy1_on  =  joy1 & ~joy1_l;
+assign joy1_off = ~joy1 &  joy1_l;
+assign joy2_on  =  joy2 & ~joy2_l;
+assign joy2_off = ~joy2 &  joy2_l;
+
+always @(posedge clk, posedge rst) begin
+    if( rst ) begin
+        mouse_1p <= 0;
+        mouse_2p <= 0;
+        but_1p   <= 0;
+        but_2p   <= 0;
+        joy1_l   <= 0;
+        joy2_l   <= 0;
+        mouse_strobe <= 0;
+    end else if(!lock) begin
+        joy1_l <= joy1;
+        joy2_l <= joy2;
+        mouse_strobe <= 0;
+        if( mouse_st ) begin
+            if( !mouse_idx ) begin
+                mouse_1p <= { cv(mouse_dy), cv(mouse_dx) };
+                but_1p   <= mouse_f[2:0];
+                mouse_strobe[0] <= 1;
+            end else begin
+                mouse_2p <= { cv(mouse_dy), cv(mouse_dx) };
+                but_2p   <= mouse_f[2:0];
+                mouse_strobe[1] <= 1;
+            end
+        end
+        if( MOUSE_EMU ) begin
+            if( joy1_on[0] ) mouse_1p[ 7:0] <= MOUSE_EMU_SENS[7:0];
+            if( joy1_on[1] ) mouse_1p[ 7:0] <= cv(-MOUSE_EMU_SENS<<1);
+            if( joy1_on[2] ) mouse_1p[15:8] <= MOUSE_EMU_SENS[7:0];
+            if( joy1_on[3] ) mouse_1p[15:8] <= cv(-MOUSE_EMU_SENS);
+            if( |joy1_on ) mouse_strobe[0] <= 1;
+
+            if( joy2_on[0] ) mouse_2p[ 7:0] <= MOUSE_EMU_SENS[7:0];
+            if( joy2_on[1] ) mouse_2p[ 7:0] <= cv(-MOUSE_EMU_SENS<<1);
+            if( joy2_on[2] ) mouse_2p[15:8] <= MOUSE_EMU_SENS[7:0];
+            if( joy2_on[3] ) mouse_2p[15:8] <= cv(-MOUSE_EMU_SENS);
+            if( |joy2_on ) mouse_strobe[1] <= 1;
+
+            // Stop the mouse when releasing the joystick
+            if( joy1_off[1:0]!=0 ) mouse_1p[ 7:0] <= 0;
+            if( joy1_off[3:2]!=0 ) mouse_1p[15:8] <= 0;
+            if( joy2_off[1:0]!=0 ) mouse_2p[ 7:0] <= 0;
+            if( joy2_off[3:2]!=0 ) mouse_2p[15:8] <= 0;
+        end
+    end
+end
+
+endmodule

snapshots/jotego_jtcores_pr1087/modules/jtframe/hdl/keyboard/jtframe_paddle.v

@@ -0,0 +1,62 @@
+/*  This file is part of JTFRAME.
+    JTFRAME program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    JTFRAME program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with JTFRAME. If not, see <http://www.gnu.org/licenses/>.
+
+    Author: Jose Tejada Gomez. Twitter: @topapate
+    Version: 1.0
+    Date: 22-6-2022 */
+
+module jtframe_paddle(
+    input              rst,
+    input              clk,
+    input signed [8:0] mouse_dx,
+    input              mouse_st,
+    input        [7:0] hw_paddle,   // hardware paddle that might be connected
+    output reg   [7:0] paddle
+);
+`ifdef JTFRAME_PADDLE_MAX
+    localparam [7:0] PADDLE_MAX = `JTFRAME_PADDLE_MAX;
+`else
+    localparam [7:0] PADDLE_MAX = 255;
+`endif
+
+`ifdef JTFRAME_PADDLE_SENS
+    localparam PADDLE_SENS = `JTFRAME_PADDLE_SENS;
+`else
+    localparam PADDLE_SENS = 0;
+`endif
+
+reg  [8:0] nx_x;
+reg  [7:0] hwpadl;
+
+always @* begin
+    nx_x = paddle + mouse_dx;
+    // check overflow
+    if( nx_x[8] ) begin
+        nx_x = mouse_dx[8] ? 9'd0 : {1'b0,PADDLE_MAX};
+    end
+end
+
+always @(posedge clk, posedge rst) begin
+    if( rst ) begin
+        paddle <= 0;
+        hwpadl <= 0;
+    end else begin
+        hwpadl <= hw_paddle;
+        if( hwpadl != hw_paddle )   // if the hardware paddle is used, follow it
+            paddle <= hw_paddle;
+        else if( mouse_st )         // but the mouse can be used too
+            paddle <= nx_x[7:0] >= PADDLE_MAX ? PADDLE_MAX : nx_x[7:0];
+    end
+end
+endmodule

snapshots/jotego_jtcores_pr1087/modules/jtframe/hdl/keyboard/jtframe_ps2key_decoder.v

@@ -0,0 +1,171 @@
+/*  This file is part of JTFRAME.
+    JTFRAME program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    JTFRAME program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with JTFRAME.  If not, see <http://www.gnu.org/licenses/>.
+
+    Author: Jose Tejada Gomez. Twitter: @topapate
+    Version: 1.0
+    Date: 26-1-2025 */
+
+module jtframe_ps2key_decoder(
+    input            clk,
+    input            rst,
+
+    // PS2 parallel data
+    input      [7:0] ps2byte,
+    input            valid,
+    input            shift,
+
+    // decoded keys
+    output reg [9:0] joy1,
+    output reg [9:0] joy2,
+    output reg [9:0] joy3,
+    output reg [9:0] joy4,
+    output reg [3:0] start,
+    output reg [3:0] coin,
+    output     [7:0] digit,
+    output reg       reset,
+    output reg       pause,
+    output reg       tilt,
+    output reg       test,
+    output reg       service,
+    output reg       vol_up,
+    output reg       vol_down,    
+    output reg [12:7]func_key,
+    output reg       plus,
+    output reg       minus
+);
+
+reg        released, extended;
+
+/* Left e06b, right e074, up e075, down e072,
+   CTRL 14, space 29, alt 11, "1" 16, "2" 1e
+   "5" 2e, "F3" 4, P 4d, W 1d, a 1c, s 1b, d 23
+   z 1a, x 22, c 21 */
+
+assign digit = { coin, start };
+
+always @(posedge clk) begin
+    if(rst) begin
+        released <= 0;
+        extended <= 0;
+        joy1     <= 0;
+        joy2     <= 0;
+        joy3     <= 0;
+        joy4     <= 0;
+        coin     <= 0;
+        start    <= 0;
+        reset    <= 0;
+        pause    <= 0;
+        service  <= 0;
+        tilt     <= 0;
+        test     <= 0;
+
+        plus     <= 0;
+        minus    <= 0;
+
+        vol_up   <= 0;
+        vol_down <= 0;
+
+        func_key <= 0;
+    end else begin
+        // ps2 decoder has received a valid ps2byte
+        if(valid) begin
+            if(ps2byte == 8'he0 /*|| ps2byte == 8'h12*/)
+                // extended key code
+            extended <= 1;
+         else if(ps2byte == 8'hf0)
+                // release code
+            released <= 1;
+         else begin
+                extended <= 0;
+                released <= 0;
+
+                case({extended, ps2byte})
+                    `ifndef JTFRAME_LITE_KEYBOARD
+                    // first joystick
+                    9'h0_22: joy1[9] <= !released;   // Button 6 (X)
+                    9'h0_1a: joy1[8] <= !released;   // Button 5 (Z)
+                    9'h0_12: joy1[7] <= !released;   // Button 4 (L shift)
+                    9'h0_29: joy1[6] <= !released;   // Button 3 (Space)
+                    9'h0_11: joy1[5] <= !released;   // Button 2 (L alt)
+                    9'h0_14: joy1[4] <= !released;   // Button 1 (L ctrl)
+                    9'h1_75: joy1[3] <= !released;   // Up
+                    9'h1_72: joy1[2] <= !released;   // Down
+                    9'h1_6b: joy1[1] <= !released;   // Left
+                    9'h1_74: joy1[0] <= !released;   // Right
+                    // second joystick
+                    9'h0_24: joy2[8] <= !released;   // Button 5 (E)
+                    9'h0_1d: joy2[7] <= !released;   // Button 4 (W)
+                    9'h0_15: joy2[6] <= !released;   // Button 3 (Q)
+                    9'h0_1b: joy2[5] <= !released;   // Button 2 (S)
+                    9'h0_1c: joy2[4] <= !released;   // Button 1 (A)
+                    9'h0_2d: joy2[3] <= !released;   // Up       (R)
+                    9'h0_2b: joy2[2] <= !released;   // Down     (F)
+                    9'h0_23: joy2[1] <= !released;   // Left     (D)
+                    9'h0_34: joy2[0] <= !released;   // Right    (G)
+                    // third joystick
+                    9'h0_5a: joy3[6] <= !released;   // Button 3 (return)
+                    9'h0_59: joy3[5] <= !released;   // Button 2 (R shift)
+                    9'h1_14: joy3[4] <= !released;   // Button 1 (R ctrl)
+                    9'h0_43: joy3[3] <= !released;   // Up       (I)
+                    9'h0_42: begin // K is used for both 2P and 3P
+                        joy3[2] <= !released;        // 3P Down  (K)
+                        joy2[9] <= !released;        // 2P Button 6
+                    end
+                    9'h0_3b: joy3[1] <= !released;   // Left  (J)
+                    9'h0_4b: joy3[0] <= !released;   // Right (L)
+                    // 4th joystick
+                    9'h0_75: joy4[3] <= !released; // 4P Up
+                    9'h0_72: joy4[2] <= !released; // 4P Down
+                    9'h0_6b: joy4[1] <= !released; // 4P Left
+                    9'h0_74: joy4[0] <= !released; // 4P Right
+                    9'h0_70: joy4[4] <= !released; // 4P Button 1
+                    9'h0_71: joy4[5] <= !released; // 4P Button 2
+                    9'h1_5a: joy4[6] <= !released; // 4P Button 3
+                    // coins
+                    9'h2e: coin[0] <= !released;  // 1st coin
+                    9'h36: coin[1] <= !released;  // 2nd coin
+                    9'h3d: coin[2] <= !released;  // 3rd coin
+                    9'h3e: coin[3] <= !released;  // 4th coin
+                    // start
+                    9'h16: start[0] <= !released; // 1P start (1)
+                    9'h1e: start[1] <= !released; // 2P start (2)
+                    9'h26: start[2] <= !released; // 3P start (3)
+                    9'h25: start[3] <= !released; // 4P start (4)
+                    `endif
+                    // system control
+                    9'h4d: pause    <= !released; //  P
+                    9'h2c: tilt     <= !released; //  T
+                    9'h06: test     <= !released; // F2
+                    9'h04: reset    <= !released; // F3
+                    9'h0c: vol_up   <= !released; // F4
+                    9'h03: vol_down <= !released; // F5
+                    9'h46: service  <= !released; //  9
+                    // Debug keys
+                    // GFX/Sound channels enable
+                    9'h0_83: func_key[ 7] <= !released;
+                    9'h0_0a: func_key[ 8] <= !released;
+                    9'h0_01: func_key[ 9] <= !released;
+                    9'h0_09: func_key[10] <= !released;
+                    9'h0_78: func_key[11] <= !released;
+                    9'h0_07: func_key[12] <= !released;
+
+                    9'h0_5b: plus  <= !released;
+                    9'h0_4a: minus <= !released;
+                    default:;
+                endcase
+            end
+        end
+    end
+end
+endmodule

snapshots/jotego_jtcores_pr1087/modules/jtframe/hdl/keyboard/jtframe_rec_inputs.v

@@ -0,0 +1,111 @@
+/*  This file is part of JTFRAME.
+    JTFRAME program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    JTFRAME program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with JTFRAME.  If not, see <http://www.gnu.org/licenses/>.
+
+    Author: Jose Tejada Gomez. Twitter: @topapate
+    Version: 1.0
+    Date: 10-2-2024 */
+
+`ifdef JTFRAME_RELEASE
+`undef JTFRAME_INPUT_RECORD
+`endif
+
+// record input data in a compressed format
+// decompress with `jtutil inputs`
+module jtframe_rec_inputs(
+    input              rst,
+    input              clk,
+
+    input              vs,
+    input              dip_pause,
+
+    input       [ 3:0] game_start,  // active low
+    input       [ 3:0] game_coin,   // active low
+    input       [ 5:0] joystick,    // active high
+
+    input       [12:0] ioctl_addr,
+
+    input       [ 7:0] ioctl_din,
+    output      [ 7:0] ioctl_merged
+);
+    parameter RECAW=13;
+`ifndef JTFRAME_INPUT_RECORD
+    assign ioctl_merged = ioctl_din;
+`else
+
+    reg  [ 7:0] recin, rec_l, fdiff;
+    reg         rec_clrd, vsl;
+    reg  [RECAW-1:0] reca;
+    wire [ 7:0] rec_data = { joystick[5:0], ~{game_start[0], game_coin[0]} };
+    reg  [ 1:0] recwsh;
+    wire [ 7:0] recmux = !rec_clrd ? (!reca[0] ? 8'hff: 8'h0 ) :
+                         recwsh[0] ?            recin : fdiff;
+    wire        rec_we = recwsh!= 0 || !rec_clrd;
+
+    always @(posedge clk, posedge rst) begin
+        if( rst ) begin
+            reca     <= 0;
+            recin    <= 0;
+            rec_l    <= 0;
+            recwsh   <= 0;
+            fdiff    <= 0;
+            rec_clrd <= 0;
+        end else begin
+            vsl <= vs;
+            if( !rec_clrd ) begin
+                reca <= reca+1'd1;
+                if( &reca ) rec_clrd <= 1;
+            end else begin
+                recwsh <= recwsh>>1;
+                if( vsl && !vs && dip_pause) begin
+                    if( &fdiff || rec_data != rec_l ) begin
+                        rec_l <= rec_data;
+                        recin <= rec_data ^ rec_l;
+                        recwsh <= 2;
+                    end else begin
+                        fdiff <= fdiff +1'd1;
+                    end
+                end
+                case( recwsh )
+                    2: begin
+                        reca  <= reca+1'd1;
+                    end
+                    1: begin
+                        reca <= reca+1'd1;
+                        fdiff <= 0;
+                    end
+                    default:;
+                endcase
+            end
+        end
+    end
+
+    // 1st byte = number of frames before applying the value change
+    // 2nd byte = input bits that changed are set high
+    // see "jtutil inputs" in "src/jtutil/inputs.go" for conveting to sim_inputs.hex
+    jtframe_dual_ram #(.AW(RECAW) ) u_record( // 2kB, set in jtdef.go
+        // Port 0: record
+        .clk0   ( clk            ),
+        .data0  ( recmux         ),
+        .addr0  ( reca           ),
+        .we0    ( rec_we         ),
+        .q0     (                ),
+        // Port 1: readout
+        .clk1   ( clk            ),
+        .data1  ( 8'd0           ),
+        .addr1  (ioctl_addr[RECAW-1:0]),
+        .we1    ( 1'b0           ),
+        .q1     ( ioctl_merged   )
+    );
+`endif
+endmodule

snapshots/jotego_jtcores_pr1087/modules/jtframe/hdl/keyboard/ps2_intf.vhd

@@ -0,0 +1,162 @@
+-- ZX Spectrum for Altera DE1
+--
+-- Copyright (c) 2009-2011 Mike Stirling
+--
+-- All rights reserved
+--
+-- Redistribution and use in source and synthezised forms, with or without
+-- modification, are permitted provided that the following conditions are met:
+--
+-- * Redistributions of source code must retain the above copyright notice,
+--   this list of conditions and the following disclaimer.
+--
+-- * Redistributions in synthesized form must reproduce the above copyright
+--   notice, this list of conditions and the following disclaimer in the
+--   documentation and/or other materials provided with the distribution.
+--
+-- * Neither the name of the author nor the names of other contributors may
+--   be used to endorse or promote products derived from this software without
+--   specific prior written agreement from the author.
+--
+-- * License is granted for non-commercial use only.  A fee may not be charged
+--   for redistributions as source code or in synthesized/hardware form without
+--   specific prior written agreement from the author.
+--
+-- THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+-- AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+-- THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+-- PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE
+-- LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+-- CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+-- SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+-- INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+-- CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+-- ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+-- POSSIBILITY OF SUCH DAMAGE.
+--
+
+-- PS/2 interface (input only)
+-- Based loosely on ps2_ctrl.vhd (c) ALSE. http://www.alse-fr.com
+
+-- This module is not used directly in JTFRAME
+-- as it is used after translatation to verilog
+
+library IEEE;
+use IEEE.STD_LOGIC_1164.ALL;
+use IEEE.STD_LOGIC_ARITH.ALL;
+--use IEEE.STD_LOGIC_UNSIGNED.ALL;
+
+-- This is input-only for the time being
+entity ps2_intf is
+generic (filter_length : positive := 8);
+port(
+	CLK			:	in	std_logic;
+	nRESET		:	in	std_logic;
+
+	-- PS/2 interface (could be bi-dir)
+	PS2_CLK		:	in	std_logic;
+	PS2_DATA	:	in	std_logic;
+
+	-- Byte-wide data interface - only valid for one clock
+	-- so must be latched externally if required
+	DATA		:	out	std_logic_vector(7 downto 0);
+	VALID		:	out	std_logic;
+	ERROR		:	out	std_logic
+	);
+end ps2_intf;
+
+architecture ps2_intf_arch of ps2_intf is
+subtype filter_t is std_logic_vector(filter_length-1 downto 0);
+signal	clk_filter	:	filter_t;
+
+signal	ps2_clk_in	:	std_logic;
+signal	ps2_dat_in	:	std_logic;
+-- Goes high when a clock falling edge is detected
+signal	clk_edge	:	std_logic;
+signal	bit_count	:	unsigned (3 downto 0);
+signal	shiftreg	:	std_logic_vector(8 downto 0);
+signal	parity		:	std_logic;
+begin
+	-- Register input signals
+	process(nRESET,CLK)
+	begin
+		if nRESET = '0' then
+			ps2_clk_in <= '1';
+			ps2_dat_in <= '1';
+			clk_filter <= (others => '1');
+			clk_edge <= '0';
+		elsif rising_edge(CLK) then
+			-- Register inputs (and filter clock)
+			ps2_dat_in <= PS2_DATA;
+			clk_filter <= PS2_CLK & clk_filter(clk_filter'high downto 1);
+			clk_edge <= '0';
+
+			if clk_filter = filter_t'(others => '1') then
+				-- Filtered clock is high
+				ps2_clk_in <= '1';
+			elsif clk_filter = filter_t'(others => '0') then
+				-- Filter clock is low, check for edge
+				if ps2_clk_in = '1' then
+					clk_edge <= '1';
+				end if;
+				ps2_clk_in <= '0';
+			end if;
+		end if;
+	end process;
+
+	-- Shift in keyboard data
+	process(nRESET,CLK)
+	begin
+		if nRESET = '0' then
+			bit_count <= (others => '0');
+			shiftreg <= (others => '0');
+			parity <= '0';
+			DATA <= (others => '0');
+			VALID <= '0';
+			ERROR <= '0';
+		elsif rising_edge(CLK) then
+			-- Clear flags
+			VALID <= '0';
+			ERROR <= '0';
+
+			if clk_edge = '1' then
+				-- We have a new bit from the keyboard for processing
+				if bit_count = 0 then
+					-- Idle state, check for start bit (0) only and don't
+					-- start counting bits until we get it
+
+					parity <= '0';
+
+					if ps2_dat_in = '0' then
+						-- This is a start bit
+						bit_count <= bit_count + 1;
+					end if;
+				else
+					-- Running.  8-bit data comes in LSb first followed by
+					-- a single stop bit (1)
+					if bit_count < 10 then
+						-- Shift in data and parity (9 bits)
+						bit_count <= bit_count + 1;
+						shiftreg <= ps2_dat_in & shiftreg(shiftreg'high downto 1);
+						parity <= parity xor ps2_dat_in; -- Calculate parity
+					elsif ps2_dat_in = '1' then
+						-- Valid stop bit received
+						bit_count <= (others => '0'); -- back to idle
+						if parity = '1' then
+							-- Parity correct, submit data to host
+							DATA <= shiftreg(7 downto 0);
+							VALID <= '1';
+						else
+							-- Error
+							ERROR <= '1';
+						end if;
+					else
+						-- Invalid stop bit
+						bit_count <= (others => '0'); -- back to idle
+						ERROR <= '1';
+					end if;
+				end if;
+			end if;
+		end if;
+	end process;
+end ps2_intf_arch;