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TSU Meeting SUNDAY — May 19, 2024

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David, Adam Trionfo, Ryan Gray, James March, Joe, Tim, Gustavo, Mike, Paul, Rich, Jack Boatwright

David opened with news of the Wednesday-night hardware SIG (Ricardo, Gustavo, Jeff Burrell, Tim Horner, Joe and Ryan), which began as a TS-Pico push and has grown into a general hardware workshop; it will open to outside members shortly. Updates on the TS-Pico itself: a mid-summer firmware release is planned (in-place upgradeable via the Pico's USB port, though some units will need a flash-ROM swap), and Joe has been iterating 3D-printed cases for the TS-Pico and Pico Video boards, with a refinement to bring both shells to 20 mm so they sit cleanly in Jeff's redesigned three-slot expansion board. David also showed a prototype eight-ROM cartridge (rotary-switch selectable, derived from a TC2068 design) and previewed two of his own Pico-based projects: an SPO256 speech-synth emulator and a 2050-modem clone that pipes serial out to a Hayes-style WiFi modem so existing 2068 terminal software can dial the internet.

David then walked through a K2 Electronics "cradle" for the TS1000 — a heavy metal enclosure with a semi-custom keyboard, expansion slots (one populated with a Z80 PIO parallel card), 64K of RAM and an RF-out, priced around $195 in 1983 with serial numbers suggesting only ~100 were built. That led to a discussion of external-keyboard interfaces for ZX81/TS1000 and TS2068 (David Stevenson's Arduino-based design, and the cartridge-slot adapter trick he used on the 2068), and Gustavo raised the SCLD-port-conflict problem the Timex has versus the Spectrum's IORQGE signal. James March then talked about his 1984 Timex Sinclair Users Encyclopedia and the Comp USA / Macronix "FIZ" hard-sectored floppy interface for the ZX81 he was sent at the time; Joe has been trying to recover the FIZ's ROM, but about a third of the address-line bonds have corroded internally and decapping quotes from Ireland came in around $400.

Ryan reported substantial progress on his ZX81/TS1000 tape-to-1510-cartridge ROM loader: rather than just unifying the existing loaders, he now mirrors the tape load process (variables, program, display file, system variables) so programs like VueCalc that checksum the system variables work, and he chased down a TS1500 boot-path bug where the loader was skipping initialization the command prompt would normally do. He has uploaded the new ROMs for Carl Miles to burn and test on real cartridges; complex multi-load games (Quicksilver titles) will need a further trick to redirect the second LOAD into the cartridge. David showed Johan Coolman's 81 High-Resolution Games book and the ZX81-World "new ZX81 games" thread as a source of 1K programs that would drop straight onto those ROMs.

Tim described porting Jonathan Cauldfield's Spectrum assembly games (Area 51, Turbo Mania) to the TS2068 by assembling first for Spectrum under Pasmo as a control, then patching the four ROM calls each one made via a lookup table. David also showed a never-soldered prototype 2068 main board from Jack Boatwright's recent shipment — Astrocade-stamped week 26 of 1983, with daughter-board placement clearly different from production — plus the multiple 1500 PCB revisions Mike has been finding. The archiving thread covered David's intake of three SINCUS tapes and several TUG PDL tapes (Paul's old library), the fuse / tzxtools workflow for splitting and listing multi-program tapes (including a microdrive-mount trick to bank multiple extractions in one session), and why ZX81/TS1000 tapes are harder to recover than 2068 tapes — the ULA's zero-crossings on the four-peak signal trip the decoders. Next meeting: Monday, June 3rd. Tim's 60th birthday was also celebrated.

Highlights

  • TS-Pico firmware release targeted for mid-summer; Joe's 3D-printed cases for TS-Pico and Pico Video are nearly final.
  • Ryan's ZX81/TS1000 tape-to-1510-cartridge ROM loader now passes VueCalc-style checksum checks and boots correctly under TS1500.
  • David previewed two new Pico-based boards: an SPO256 speech-synth emulator and a 2050-modem clone with a Hayes-AT WiFi front-end.
  • Deep-dive on the rare K2 Electronics cradle for the TS1000 (~$195 in 1983, semi-custom keyboard, likely under 100 units built).
  • Joe's attempt to recover the Comp USA / Macronix FIZ floppy interface ROM is stuck on corroded internal address-line bonds.

Projects discussed: TS-Pico · TS1510 Cartridge Interface Clone · Library Tape Archiving Process Topics: Hardware projects & new boards · Cartridges, EPROM & dumping · Pico / modern interfaces (UnoDos, etc.) · TS1000 / ZX81 / TS1500 · Tape & library archiving (TAP/TZX) · Tape, cassette & loading

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