I used back in the '80s. It provided data capture and disassembly of a running 6502.
With more time than money I started working on using a Teensy microcomputer as a logic analyser and now have
a working system. The Teensy runs at around 96MHz so it is able to keep up to monitoring and capturing the
address/data/control signal on my OSI 1MHz CPU. After data capture I upload the data to a linux box where
I have a disassembler that can trace the program flow. I shows the 6502 assembler interspersed with the
data reads and writes.
No fancy GUIs, all command line but it is all working amazingly well. So far it has shown me my C3 is stuck on
trying to move the floppy disk to Track zero. (more on that later)
Here is the the system wired to a 505 CPU:
And here is a sample the trace program showing CPU fetching the reset vector
and starting to execute code at 0xffa0. The reads are showing with plus signs (+) and
writes with minus signs (-).
Code: Select all
fffc+ a0
fffd+ ff
ffa0 d8 CLD
ffa1+ a2
ffa1 a2 d8 LDX #$d8
ffa3 a9 d0 LDA #$d0
ffa5 85 fe STA $fe
00fe- d0
ffa7 a0 00 LDY #$00
ffa9 84 fd STY $fd
00fd- 00
ffab a9 20 LDA #$20
ffad 91 fd STA ($fd),Y
00fd+ 00
00fe+ d0
d000+ 20
d000- 20
ffaf c8 INY
ffb0+ d0
ffb0 d0 fb BNE $fb
ffb2+ e6
ffad 91 fd STA ($fd),Y
00fd+ 00
00fe+ d0
d001+ 20
d001- 20
ffaf c8 INY
ffb0+ d0
ffb0 d0 fb BNE $fb
ffb2+ e6
ffad 91 fd STA ($fd),Y
00fd+ 00
00fe+ d0
d002+ 20
d002- 20
The code is all on github and a more detailed write up on http://www.lockett.ca
Direct Link to documentation ---> http://lockett.altervista.org/logic65/logic65.html