LisaList2

Ha, neat! AI can certainly automate a lot of tasks... As I was writing Lisavox, I felt that the choice to hand-code everything was basically an indulgence on my part; I could have asked an AI to take care of most of the Python in particular and it would surely have done fine.

Anyhow, there are some truly heroic if-else ladders in that code; if I were asked to review it in my day job I would recommend use of Python's more recent match/case construct. You could surely ask Claude to rewrite it so that it did, but if the code works there is not much reason to tamper with it. I'd also ask for type annotations because I am a stickler for that; there too I'd expect Claude to be flawless, basically.

I'd ask Claude to use the unittest module for the tests (another thing it could fix for sure).

But probably more useful than any of this would be to do some really intensive testing sometime. Take some reasonably large 68000 binary and have it disassemble it, then feed that back into an assembler. If you get the same binary back that you started with, then that's a pretty good demonstration of effectiveness!

I wonder what the COP issue was. Do you think you'll be able to break the 60 MHz barrier?

Perfect, I just published the repo:

https://github.com/alexthecat123/Interactive-68K-Disassembler

Good idea about the cycle counting; I asked it to add that functionality and it seems to work just fine. I didn't check the correctness of its cycle-counting for every instruction, but I spot-checked a bunch of them and they were all correct.

Any instructions that require memory accesses are going to take a varying number of cycles depending on how fast DTACK is asserted, so I asked the program to print the base cycle time assuming that DTACK is asserted immediately. For non-memory instructions, it just prints the cycle time on its own, but for memory instructions, it prints the cycle time with a "+" after it to indicate that the instruction can take longer depending on how long it takes for DTACK to be asserted.

Quote from: AlexTheCat123 on January 28, 2026, 01:14:43 PMIs this something that anybody else would be interested in having?

Yes, that's a great idea; I think that would be useful.

I can imagine circumstances (thinking of you, Stepleton) where it would be useful to know how many CPU and bus cycles would be used.

Last night, I was messing around with overclocking the LisaFPGA board to a 60MHz DOTCK and got tired of disassembling instructions by hand during the troubleshooting process, so I needed to turn to a 68K disassembler. But as I've learned many times in the past (including earlier in this project), there just aren't any good options out there, especially interactive ones where you can type hex digits in at a prompt, hit return, and get your result out in real time. So I asked Claude to write me one, and boy did it deliver!

It came up with a full-featured interactive disassembler, complete with a test suite that it used to confirm that everything was fully-working, and it's helped me figure out why the Lisa is a bit flaky at 60MHz (a COP-related issue). I'm honestly really impressed with what it produced!

Is this something that anybody else would be interested in having? If so, I'll stick it up on my GitHub (with the disclaimer that the code was AI-generated of course) and other people can try it out!

Ha, awesome! Thanks for sharing that.

This past weekend at VCF Montreal we demoed LisaVox to a very enthusiastic crowd. Here are two attending "fans" listening it - they heard it despite the screen not showing the actual playing

It's interesting to note slightly different circuits to the ones I've transcribed in some motherboard schematics: for the Lisa 1, some different values in this schematic as well as a 100R resistor between Q1 emitter and Q2 collector.

Meanwhile the Lisa 2/10 motherboard (note: link goes to a TIFF file) shows a single component U2 creating the video signal from CVOUT and VID; I presume this is the hybrid circuit that has been mentioned elsewhere?

Here is my attempt to recreate these driver circuits in the Falstad CircuitJS simulator: link

It would be a good idea to check to see whether I've copied the schematics faithfully. There is certainly a difference in levels apparent in both in the simulated oscilloscope. (Tip: mouse over the L1_RCA and L210_RCA labels to see which label is which in the simulated 'scope --- note that it may still be hard to tell if you have certain kinds of colourblindness. The L1_RCA has consistently higher voltages everywhere.)

Some oscilloscope waveforms and measurements (note that timing measurements collected via Logic Analyzer will be much more precise than those collected from this oscilloscope).

Removing the 75 Ohm load approximately doubles the voltages.

Quote from: stepleton on January 24, 2026, 11:56:24 AMI've decided to give this another look. I can confirm that I need to turn 75R termination ON for the Lisa 1 and OFF for the 2/10.

Thank you for confirming this!   

Due to the composite video's analog signal path and 40+ year old Lisa hardware combined with variations in RGBtoHDMI builds, this solution is never going to be plug-and-play.  Some tweaking of the settings is bound to be required for each user. 

Rick