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Timex Sinclair User Group Meeting with European Friends — September 25, 2022

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David, Adam Trionfo, Tim, Jeff Burrell, Stuart, Ingo, Joe, Carl Miles, Claudius

David opened with a BASIC Mandelbrot listing by Roald Schack (Capital Area Timex Sinclair User Group), one of many programs he's been keying in from Jack Boatwright's three boxes of donated newsletters — roughly 5,000 articles indexed so far. Tim demonstrated progress on his Arduino-based TS2040 / ZX printer interface: a Mega with a small shield (one pull-down resistor on /WR) drives the printer directly off the ZX81 / TS2068 edge connector, and he has just gotten Windows printing into it via an emulated serial port using Epson-style escape codes, with a smaller Uno shield and an open-source release planned. Stuart pushed for a generic Arduino-shield-on-Timex-bus project to give modern hobbyists A/D, sensors and Wi-Fi on their old machines, and floated the inverse idea of an ESP32 that captures 2040 output and serves it as a web page so any modern printer can stand in for the 2040.

Hardware show-and-tell included Joe's heavily-modified ZX81 (tactile keyboard from a salvaged Timex/Sinclair, composite-out mod, 64K RAM module that copies ROM into RAM for patching) and his TZX-style SD-card tape players — one a multi-system unit from New Zealand with touchscreen and remote-line sensing. Joe and Tim also covered the BackBit cartridge across Astrocade / Atari 130XE / Odyssey², Spectravideo SV-318 ownership, and Heathkit ET-3400 trainers. Tim explained the trick the C64-scene ROM switchers use — hold the host CPU in reset until the Arduino is ready, then release — as a way to intercept the 2068 boot. He and Stuart also discussed the ZX-Wespi / Wespi-Nano ESP32 board: minimal version drops in on the EAR/MIC for fast turbo-loading of TAP files from Wi-Fi.

Ingo joined after a long absence to show his new Creality 3D printer running OctoPrint with a webcam, currently printing a ZX81 case shell (10+ hours). Tim had already printed the same model and shared layout tips (print vertically, watch the keyboard-step overhang); they also recommended printing the spring-action DIP pin straightener from Thingiverse. Jeff reported that his TS2068 software work is on hold but he's found FPGAs in stock at DigiKey and is moving back to an FPGA solution (with video, SD and Wi-Fi) instead of a CPLD. David walked through his EasyEDA design for a small board that taps the SCLD's YUV signals inside the 2068, does the analog matrix back to RGB, and feeds a Sega Genesis RGB-to-HDMI converter — aiming to bypass the switching-regulator noise that wrecks composite capture. A general SMD-vs-through-hole technique discussion followed (drag-soldering with a wider tip, 0603 by hand under a microscope, hot-plate reflow with PCBway stencils), along with a survey of EDA tools in use: EasyEDA, KiCad, Altium Circuit Studio.

Stuart gave background on Zebra Systems' Zebra OS 64 (Jeff Street did the work; Al Hartman would remember the history; probably under 50 sold, partly because it needs RGB or a green-screen monitor) and recalled hand-laying single-sided PCBs with tape-and-donuts and getting boards etched in Brooklyn. Claudius (UK) presented his from-scratch recreation of the Dataskip / Romantic Robot VideoFace digitizer for the Spectrum: he re-traced the schematic, fabbed PCBs in China, found two counters mis-wired by overlaying photos of the original, and got it digitizing PAL composite at about three frames per second (1-bit, threshold-adjustable, six-frame animation buffer, saves SCREEN$ to tape / Microdrive / Opus / +D). He's also done a Jupiter Ace recreation, an AY sound interface and PT3 player for it, and a TC2048 redesign with Mike Smith's SCLD replacement. Adam closed with a question about reversing the TAP-to-cartridge process — going from an AROS cartridge ROM (e.g. the Q-bert prototype, or Zebra OS 64) back to a tape image — which David and Carl noted would need to honour the AROS header bytes and basic system-variable setup; worth a future write-up. Adam also showed the book Creating Qbert by Warren Davis and the New Wave Toys mini Qbert cabinet with its real solenoid knocker. Next meeting confirmed for Monday 3 October.

Highlights

  • Tim demoed his Arduino TS2040 / ZX printer interface now printing from Windows via emulated serial; open-source release planned.
  • Claudius (UK) recreated the Dataskip / Romantic Robot VideoFace digitizer from scratch — ~3 fps 1-bit PAL capture on Spectrum/TC2048.
  • David walked through his EasyEDA YUV-to-RGB board that taps the SCLD inside the 2068 and feeds a Sega Genesis RGB-to-HDMI converter, bypassing switching-regulator noise.
  • Jeff is switching back to an FPGA solution for the 2068 (video + SD + Wi-Fi) after finding stock at DigiKey.
  • Ingo showed his new Creality 3D printer running OctoPrint, currently printing a ZX81 case shell.

Projects discussed: ZX-Wespi / Wespi-Nano · TAP-to-Cart — TS2068 Cartridge Conversion · FPGA "Advanced 2068" Topics: Printers & plotters · Video upgrades (composite, RGB, HDMI) · Hardware projects & new boards · Cartridges, EPROM & dumping · Pico / modern interfaces (UnoDos, etc.) · Newsletters & documentation

Summary generated from the meeting recording; the full transcript is kept in the group's private archive.