THE OSI® GAZETTE
OSI C1P Control Functions
C. A. Stewart
Adrian, MI
In a previous issue of COMPUTE! a basic poke version of my control function was published. Since that time I have discovered a method to implement a RUN command with a single key stroke much like the PET run key.
The main routine resides in page 2 in this revision (I used page 0 in my previous version but the added functions required relocation) and the one key screen clear resides in page 0. Refer to figure #1 (Flow chart) for discussion of the program functions.
In normal operations locations #536 and #537 contain vectors set by system ROM to the input routine $FFBA in typical 6502 hi/lo order i.e. $BA in location #536 and $FF in location #537. (Note for new computerist the symbol $ in machine language signifies HEX number, not string and the symbol # signifies a decimal number). By changing the vectors in these locations we force the system into our routine first and then return control to the ROM, to implement in this example we poke #536 with #128 and #537 with #002 (POKE536, 128 : POKE537, 2) in one command line! It should be noted that a break warm start will require this poke command line since a warm start re-initializes these vectors.
A useful basic program for HEX to DEC and DEC to HEX is included in listing #3 for readers without tables or a TI HEX calculator.
When the routine starts we go to the input subroutine $0280 which jumps to $FFBA (input a character) and compare to the following.
| Control L | Load command |
| Control S | Save command |
| Control A | Run Command |
| Escape Key | List command |
| Rubout Key | Screen Clear |
If any of the comparisons are true then the appropriate subroutine in ROM is called, otherwise normal program operation continues. I chose Control A for the Run function for two reasons. First the logical choice, Control r, is utilized for a remove in the cursor control package I have in ROM and because of its location next to the control key. The command keys can be changed to whatever the user requires by replacing the compare data with the appropriate key numbers. Control A = $01 and follows thru with control Z = #26. (see graphics manual.)
Listing #1 is the machine language routine. Listing #2 is the BASIC poke program. The machine language screen clear is callable in BASIC via the USR function. To use load and run, code erases itself, leaving the machine code in page 0 and 2, and doesn't require any normal usable memory.
D8 PHA D9 LDA #$20 ; LOAD SPACE CHR DB LDX #$00 ; LOAD ACCX W/0 DD HERE STA $D000, X ; STORE SPACE CH R ON SCREEN E0 STA $D100, X E3 STA $D200, X E6 STA $D300, X E9 INX ; INC X EA BNE HERE ; BRANCH TO $DD I F NOT EQUAL TO 0 EC PLA ED RTS
280 JSR $FFBA ; JUMP TO INPUT SUBROUTINE $FEED ON C4P 283 CMP #$0C ; COMPARE TO CONT L 285 BNE CONT S ; BRANCH TO CONTROL S 287 JSR $FF8B ; EXCUTE LOAD COMMAND 28A CONT S CMP #$13 ; COMPARE TO CONTROL S 28C BNE RUB ; 28E JSR $FF96 ; EXCUTE SAVE COMMAND 291 RUB CMP #$7F ; COMPARE TO RUBOUT 293 BNE ESC ; 295 JMP $D8 ; EXCUTE SCREEN CLEAR 298 ESC CMP #$1B ; COMPARE W/ESCAPE 29A BNE RUN ; 29C JMP $A4B5 ; EXCUTE LIST 29F RUN CMP #$01 ; COMPARE W/CONT A2A1 BNE END ; 2A3 JSR $A477 ; INITALIZE ROUTINE 2A6 JSR $A5C2 ; RUN ROUTINE 2A9 END RTS ;
Listing 1
10 REM MACHINE LANG SUBROUTINE FOR OSI C1P/C4P 20 REM CHARLES A. STEWART 30 REM 3033 MARVIN DR. 40 REM ADRIAN, MICH 49221 60 FOR X = 640TO681 : READA : POKEX, A : NEXT 65 REM FOR C4P LINE 70 CHANGE 186, 255 TO 237, 254 70 DATA32, 186, 255, 201, 12, 208, 3, 32, 139, 255, 201 80 DATA19, 208, 3, 32, 150, 255, 201, 127, 208, 3, 76 90 DATA216, 0, 201, 27, 208, 3, 76, 181, 164 100 DATA201, 1, 208, 6, 32, 119, 164, 32, 194, 165, 96 110 FORX = 216TO237 : READA : POKEX, A : NEXT 120 DATA72, 169, 32, 162, 0, 157, 0, 208, 157, 0, 209, 157, 0, 210 130 DATA157, 0, 211, 232, 208, 241, 104, 96 150 POKE11, 216 : POKE12, 0 : POKE536, 128 : POKE537, 2 160 PRINT " * CONTROL VERSION #1" : PRINT " * BY CHARLES A. STEWART" 165 PRINT : PRINT 170 PRINT "ESC LISTS" : PRINT "RUBOUT GIVES SCREEN CLEAR 180 PRINT "CONTROL S = SAVE" : PRINT "CONTROL L = LOAD 185 PRINT "CONTROL A RUNS PROGRAM 200 NEW
Listing 2
10 REM CHARLES A. STEWART 20 REM 3033 MARVIN DR. 30 REM ADRIAN MI 49221 40 REM 517-265-4798 50 REM NOVEMBER 22, 1980 60 REM DEC TO HEX AND HEX TO DEC CONVERSON PROGRAM 100 DIMA$(16), S$(16) : FORX = 1 TO 16 : READA$(X) : READS$(X) : NEXT 110 DATA 0000, 0, 0001, 1, 0010, 2, 0011, 3, 0100, 4, 0101, 5, 0110, 6 120 DATA 0111, 7, 1000, 8, 1001, 9, 1010, A, 1011, B, 1100, C, 1101, D, 1110, E 130 DATA 1111, F 135 S$ = "0123456789ABCDEF" 140 POKE 11, 0 : POKE12, 253 : X = 0 : Y = 0 : W = 0 : Q = 0 : I = 0 : E$ = "0" 150 FOR X = OTO40 : PRINT : NEXT : PRINT "A > DECIMAL TO HEX" : PRINT 160 PRINT "B > HEX TO DECIMAL" : PRINT : PRINT "YOUR SELECTION" : X = USR(X) 170 IFPEEK(531) = 65THENPRINT "DEC TO HEX CONVERSION" : GOTO3010 180 IFPEEK(531) = 66THENPRINT"HEX TO DEC CONVERSION" : GOTO2010 190 GOTO150 2010 PRINT : INPUT "HEX NUMBER" I$ : IFLEN(I$))4THEN2010 2020 IF LEN(I$)< > 4THEN1$ = E$ + I$ : GOTO2020 2040 FOR X = 1 TO 4 : FOR Y = 1 TO 16 2050 IFMID$(I$, X, 1) = MID$(S$, Y, 1) THENB$(X) = A$(Y) 2060 NEXT Y : NEXT X 2070 B1$ = B$ (1) + B$(2) + B$(3) + B$(4) 2080 PRINT : PRINT I$" IN BINARY = " PRINTB1$ 2100 X = 1 : W = 0 : Q = LEN(B1$) : I = 0 2120 Y$ = MID$(D1$, Q, 1) : Y = VAL(Y$) : I = Y * X : W = W + I : X = X * 2 2130 Q = Q – 1 : IFQ < > 0GOTO2120 / 2140 PRINT : PRINTI$" IN DECIMAL = " ; W 2150 PRINT : PRINT "TYPE ANY KEY TO CONTINUE" : X = USR(X) : GOTO2010 3010 PRINT : INPUT "DECIMAL NUMBER"; I$ : I = VAL(I$) : Y$ = " " Y = 65536 3012 Y = Y/2 3015 IFI>65535THENPRINT : PRINT"TOO LARGE " : GOTO2150 3030 X = INT(I/Y) : IFX = 0THENY$ = Y$ + "0" GOTO 3050 3040 Y$ = Y$ + "1" : I = I – Y 3050 Y = Y/2 : IFINT(Y) = 0THEN3200 3060 GOTO3030 3200 PRINT : PRINT$ "IN BINARY = " PRINTY$ 3210 X = 2 : Y = 4 3215 RE$ = " " 3220 A$ = MID$(Y$, X, Y) : FOR W = 1 TO 16 : IFA$ = A$(W)THENRE$ = RE$ + S$(W) : GOTO3240 3230 NEXT W 3240 X = X + 4 : IF X> 14THENGOTO3260 3250 GOTO3220 3260 PRINT : PRINTI$" IN HEX=" ; RE$ 3265 PRINT "TYPE ANY KEY TO CONTINUE" : X = USR(X) : GOTO3010 OK
Listing 3