Intellivoice SP0256 Simulation

[TheProgrammerIncarnate]

One week ago I found that a forum member had cleaned up the die photos of the SP0256 (thanks JohnPCAE) and posted them on this thread. With all that work already done, it would only take a few days to get a simulation working! No, not from scratch, as over the course of the year I'd been working on a simulation of the AY-3-8500 PONG-clone chip based the visual6502 team's work. It was not too hard to use my earlier tools, code, and experience to turn the labeled die photos of the SP0256 into a javascript simulation. I managed to get a beta version working within a week! (That's RetroChallenge speed!)

 

HERE is a copy I hosted on droppages. The source is on GitLab for anyone who knows JavaScript.

 

This particular chip came from the Intellivoice expansion module, and contains 2 kilobytes of ROM for game related phrases (The ROM is the big rectangle on the middle right) If you zoom in on it, you can see the individual transistors (green) which encode "1"s in the ROM. The chip has a lot of transistors, 15681 to be exact (and that's not counting the pullup transistors.) These and the 4255 electrically isolated nodes are combined to form a list of 39432 polygons (glad I processed these automatically.)

 

Its still a WIP, I fixed about two dozen errors in the highlighting and my code, but there are still some preventing the all of the circuitry from working properlly. For example, the instruction decoder is not disabled while a new instruction is being shifted in, resulting in spurious instructions activating. Once all bugs are ironed out, we'll have correct schematic files, potentially leading to better real time emulation. In the meantime, I'll keep posting updates on this forum and my blog

[JohnPCAE]

Excellent! When you're finished, would you mind posting an updated image so we can have a correct reference (preferably in something lossless like PNG). And yes, it was about four months of work