!!!PSC Simple Debugger
[A simple 6502 debugger/atari000.png]
This is a very simple debugger I have written years ago. It has been used to figure out the hotspots of a program or to slow down the program to be examined.
The "BUG.COM" executable will install a VBI with a wait loop. This loop is slowing down the Atari and thus other programs running. It can be adjusted with "START" and "SELECT". In the top line the tool will display the current CPU instruction pointer. This instruction pointer can be copied to the field on the right with the "OPTION" key (e.g. to examine a specific code area with a hardware monitor such as BiboMon, QMeg or Turbo-Freezer).
!Disk
[A simple 6502 debugger/sbug6502.atr]
!Source
* [A simple 6502 debugger/BUG.SRC.pdf]
{{{
00010 .LI OFF
00020 ***************************
00030 * PSC DEBUGGER V.1 *
00040 ***************************
00050 ;
00060 CASINI = $02
00070 BOOT = $09
00080 CONSOL = $D01F
00090 SDLST = $0230
00100 HLPFLG = $2DC
00110 VCOUNT = $D40B
00111 BZAHL = $238
00120 ;
00130 ; OS ADRESSEN
00140 ;
00150 SETVBV = $E45C
00160 XITVBV = $E462
00170 ;
00180 ;
00190 .OF "D:BUG.COM"
00200 .OR $400
00210 ;
00220 HLPMEM .HX 000000000000
00240 DL .HX 707042
00250 .DA TEXT
00260 .HX 0001
00270 DLEND .HX 0000
00280 TEXT .AT "\240–”√≠¬’«¸¡√‘\240®∞∞∞∞∞©Ωæ®∞∞∞∞∞©¸ƒ≈î∞∞∞∞∞©"
00290 DECLO .HX 10E8640A
00300 DECHI .HX 27030000
00310 ZIFFER .AT "00000"
00320 DELAY .HX 77
00330 ;
00340 ;
00350 ;
00360 ;
00370 X
00380 LDA #X
00390 STA CASINI
00400 LDA /X
00410 STA CASINI+1
00420 ;
00430 LDA BOOT
00440 ORA #$02
00450 STA BOOT
00460 ;
00470 LDA #$04
00480 BIT CONSOL
00490 BNE SETVBI
00500 RTS
00510 ;
00520 SETVBI
00530 LDY #START
00540 LDX /START
00550 LDA #$07
00560 JSR SETVBV
00570 RTS
00580 ;
00590 .OR $0600
00600 ;
00610 START LDA SDLST+1
00620 CMP /DL
00630 BEQ BUG
00640 LDA SDLST
00650 CLC
00660 ADC #$03
00670 STA DLEND
00680 LDA SDLST+1
00690 ADC #$00
00700 STA DLEND+1
00710 LDA #DL
00720 STA SDLST
00730 LDA /DL
00740 STA SDLST+1
00750 ;
00760 BUG
00770 LDX #6
00780 .1 PLA
00790 STA HLPMEM-1,X
00800 DEX
00810 BNE .1
00820 LDX HLPMEM+1
00830 LDA HLPMEM
00840 JSR BINDEZ
00850 ;
00860 XDSPL
00870 LDX #5
00880 LDY #$12
00890 JSR DSPL2
00900 ;
00910 LDA CONSOL
00920 CMP #6
00930 BNE RESTORE
00940 LDX #5
00950 LDY #$1B
00960 JSR DSPL2
00970 ;
00980 RESTORE
00990 ;
01000 LDX #0
01010 .1 LDA HLPMEM,X
01020 PHA
01030 INX
01040 CPX #6
01050 BNE .1
01060 LDA DELAY
01070 LDX #0
01080 JSR BINDEZ
01090 LDX #5
01100 LDY #$26
01110 JSR DSPL2
01120 DELMIN
01130 LDA CONSOL
01140 CMP #5
01150 BNE DELPL
01160 LDA DELAY
01170 CMP #$10
01180 BMI DELPL
01190 DEC DELAY
01200 DELPL
01210 LDA CONSOL
01220 CMP #3
01230 BNE WAIT
01240 LDA DELAY
01250 CMP #$7B
01260 BPL WAIT
01270 INC DELAY
01280 WAIT
01290 LDA DELAY
01300 .1 CMP VCOUNT
01310 BNE WAIT
01320 JMP XITVBV
01330 ------------------------------
01340 BINDEZ
01350 STA BZAHL
01360 STX BZAHL+1
01370 LDX #4
01380 VORBES
01390 LDA #$10
01400 STA ZIFFER,X
01410 DEX
01420 BPL VORBES
01430 LDX #0
01440 STELLE
01450 LDA BZAHL+1
01460 CMP DECHI,X
01470 BNE TSTHI
01480 LDA BZAHL
01490 CMP DECLO,X
01500 TSTHI
01510 BCC KLEINER
01520 SEC
01530 LDA BZAHL
01540 SBC DECLO,X
01550 STA BZAHL
01560 LDA BZAHL+1
01570 SBC DECHI,X
01580 STA BZAHL+1
01590 INC ZIFFER,X
01600 JMP STELLE
01610 KLEINER
01620 INX
01630 CPX #4
01640 BNE STELLE
01650 CLC
01660 LDA BZAHL
01670 ADC ZIFFER+4
01680 STA ZIFFER+4
01690 RTS
01700 ------------------------------
01710 DSPL2
01720 LDA ZIFFER-1,X
01730 ORA #$80
01740 STA TEXT,Y
01750 DEY
01760 DEX
01770 BNE DSPL2
01780 RTS
01790 ------------------------------
01800 .OR $2E0
01810 .DA X
01820 ------------------------------
}}}