For the shuttle I ended up on, may 11th: https://app.tinytapeout.com/shuttles/ttsky26a
Here's a link to me! https://app.tinytapeout.com/projects/3829
Wow, what a neat concept TinyTapeout is! Good luck with it :)

I skimmed through the ISA doc, and this actually looks much like an older version of ...

I'm still at it! I hadn't done much work on it in a while; dealing with verilog is *very* tedious, and I couldn't get the tests working. Thankfully, Claude is rather good at verilog, which has allowed me to try a lot of ideas very quickly, despite not having very much time for the project. I'm ...

Certainly the first few paragraphs are not bad - but it (rightly) veers off into a lot of fairly open-ended troubleshooting tips because I'm not sure there is a concrete reason why this would happen - it's unusual, so you do just need to diagnose it carefully. I think the suggestions it gave are ...

Again, ~EEPROM in blue.
Vector pull, which is definitely surprising:
...
And Sync:
...
Sync looks right, I think. Seven clock cycles between instructions, which doesn't look right; should be four for an absolute address, no?

Neil
Ah I see, I misread the horizontal scale on the scope. In that case ...

Agreed about "bra init", good spot, sometimes these things are easy to overlook! It wouldn't explain the RWB/EEPROM oscilloscope trace but maybe that was a probing error? JSR is the only instruction I can think of that executes two write cycles (but not three) in a row, but JSR requires more read ...

That .switch/.case/.default/.endswitch block is a shorthand for .if/.elsif/.else/.endif...
Pardon me for being a gruff curmudgeon, that’s too much complication in an assembler, in my opinion.

Programming in assembly language means one is working in an inherently low-level environment that is ...

Nice improvement! I think in my fast DIP system I got to about 35MHz but either the Dormann tests or my memory test started to fail in soak testing above that point. Similar to what you said here, that system also deliberately had very little on the data bus - just the 6502, RAM, and some ...

In case it's useful to you: I have some code here to read from FAT32 filesystems on SD cards, which could be retargetted to CF fairly easily I should think: https://github.com/gfoot/sdcard6502/blob/master/src/libfat32.s

My code only supported reading, but others have extended it with code to write ...

That last one is similar to that in the BBC Micro:
bbcimicrooscillator.png

I've always used this circuit though - similar to barnacle's but with one resistor missing:
Screenshot 2025-11-25 004107.png

I don't know whether this would work better or worse, but thought I'd share in case you want ...

That picture reminds me, I saw a physical puzzle video on YouTube recently where you had to fit the digits from 0 to 9 in a 11x11 grid. The digits were rendered in 3x5 cells like yours ...

Is it possible your "visible" signal is unstable?
Genius! Literally genius, George, thank you so much! See attached now. Yep, the VISIBLE pin was not soldered right, again. Gosh, I really need to check my footprints. None of this would have happened if I paid more careful attention to my ...

I'm glad it's working now - subtle connection issues can be hard to diagnose!

For the resistors, I presume you have one channel connected to R through a 510ohm resistor, another connected to B through a 510ohm resistor, and both channels connected to G through 1k resistors? The white levels do look ...

I believe so but I haven't used it in that mode, I also suspect it would only output 3.3V so would at least need level-shifting if used this way.

I have recently acquired a Digiac 2000 with the Z80 board and the MACIII 6502 board. I would like to connect my Digiac MACIII board to a PC using an RS232 to USB converter. I have read all the posts within this topic and there has been some great information.

I have created a cable between the ...

This project made me wonder how fast the 65C02 could go if it wasn't slowed down at all waiting for external devices. My idea was to take a recording of the bus activity while running a program (e.g. the Dormann tests), and then replay the data bus activity without external devices connected ...