In this week’s meeting of our group, we were joined by Tim Horner (from New Zealand!), Ingo Schmied, Ryan Gray, Jeff Burrell and Stewart Newfeld.
David talked about a disassembly of the TS2068 ROM he’s compiled from several sources and edited/enhanced over several years. David uploaded it to Google Docs, where you can view (and request access to edit):
https://docs.google.com/document/d/15ACR2v9pRQQFXG7LYwLvheU69GfC30-x4fCD7uYe1BQ/
Ingo gave us an update on his ZX81/TS1000 replacement keyboard, which uses full-size keyswitches. He’s built an adapter that connects the keyboard to the expansion bus, much like the Memotech keyboard, and does not require opening the ZX81/TS1000 to install.
You can learn more about Ingo’s keyboard on his website: https://blog.codesurfer.dev/
Tim showed us his keyboard, with custom keycaps from WASD. Tim is working from the opposite direction: he purchased a 60%-size keyboard, installed his custom keycaps and built an adapter to connect from USB to the ZX81. His keyboard also works with Windows/Mac computers and can be used with emulators.
This is the keycap set Tim used: https://www.wasdkeyboards.com/keychron-k2-84-key-custom-cherry-mx-keycap-set.html
Tim also talked about a video converter circuit he’s using, built from an open-source project available on Github:
https://github.com/hoglet67/RGBtoHDMI
We briefly talked about a ESP32-based server/video circuit for the ZX81, too. It’s also on Github:
https://github.com/holmatic/zx-iot-video
Ryan showed us some of his collection, which led to a discussion with Stewart about the membrane replacement PCBs he’s selling on eBay. these replacement keyboards use microswitchs and are an excellent replacement option for the ZX81/TS1000. The Spectrum version can be used with the TS1500, since they use the same case and connector layout.
Jeff gave a brief update on his project to provide a way to save/load to/from SD cards for the TS2068.
We chatted with Stewart about his pre-Zebra work on a digital-to-analog (DA) converter board for S-100 computer systems. Stewart and his friends Dorothy Siegel and Michael Abrams developed the board, which Dorothy demonstrated at the First Philadelphia Computer Music Festival, part of a show called Personal Computing ’78 whihc was held August 25, 1978 at the Philadelphia Civic Center. The music was later released by as a record by Creative Computing.
You can hear the DA boards in action, with Dorothy on clarinet, on this podcast:
https://ataripodcast.libsyn.com/antic-interview-392-dorothy-siegel-pioneer-in-computer-music
Adam and David chatted a bit about Tad Painter’s Speech Synthesizer (2068) and the work he did in documenting the program. That led to a conversation about a speech synthesizer Stewart built based on the Votrax SC-01 speech chip.