TSU Meeting Sunday — January 21, 2024

Tim, Carl Miles, Ryan Gray, Adam Trionfo, David, João, Gustavo, Paul

Carl Miles and Ryan Gray walked the group through their in-progress Spectrum-to-2068 software converter — a tool that disassembles a Spectrum TAP/TZX, identifies Spectrum ROM calls, and rewrites them to the 2068's equivalents so Spectrum machine-code titles can run on stock 2068 hardware without a Twister board or Spectrum ROM cartridge. They're starting from a Syntax newsletter table of ROM calls (their "Rosetta stone"), accounting for jumps that land a few bytes into a routine, and looking at the Skoolkit disassembler to separate code from data. Low-hanging-fruit targets were discussed (Manic Miner, Cybernoid; Horace titles were flagged as IP-risky after recent UK takedowns).

Carl reported on the NTSC conversion of Ryan's ZX Spectrum (originally from the Bill Miller collection): the crystals were already swapped, but PAL output persisted, so they sourced 6C011 NTSC ULAs from Mutant Caterpillar (~£75 each, last three in stock) to drive the 50/60 Hz frame counter change. Gustavo and Chris Smith's ULA-book research informed the diagnosis. Cybernoid loaded from tape but ran at the wrong pitch — prompting a discussion of whether the converter should also patch beeper/timing routines. Carl also previewed his TS1000→TS1500 conversion: a silver-painted 1000 case running an original 1500 ROM (supplied by Andy) with 16K internal RAM, composite mod, and a NOS TS1000 membrane keyboard from Stuart's stash. The SCLD-only auto-RAM-expansion trick is out of scope for that build.

João (Portugal) gave a long history segment tied to the launch of the refreshed Timex Computer World website (rebuilt with João Encarnado). He covered the Ferranti-ULA vs SCLD 1500 question, evidence in Timex Portugal documentation of an "old PCB TS1000 size" 1500, Landry as the first Sinclair importer into Portugal, the Argentina/Czerweny path via Timex Portugal during the Falklands embargo, the Poland trade-deal (computers for Neptun monitors and groceries, derailed by Amstrad's Sinclair acquisition blocking ROM access for the TENET educational network), and the recovered Timex Portugal joystick-port barcode reader that was demoed last June.

Carl showed five TS-2050 modem boards (also from the Bill Miller collection, via Tim) that he's converting to dual modem / RS-232 operation using four-pole latching relays (so the relay coils don't draw constant current over the interface cable) and a bicolor LED for the mode indicator. Ryan then demonstrated his ZX Spectrum terminal: FUSE in Spectrum mode with Interface 1 RS-232 emulation, the serial endpoints wired to Unix named FIFOs, SoCat shuttling bytes to a login shell on his Pi 400 and then out to FozTextBBS over TCP. Tim called for articles for ZX-Zine #11 (planning a print run plus print-on-demand); David announced his cleaned-up scan of the 1984 TS2068 Technical Manual is now available print-on-demand and that he's about to scan the original blueprint schematics. Next meeting: Monday, February 5th, 9pm.

Highlights

Carl and Ryan are building a Spectrum-to-2068 converter that rewrites Spectrum ROM calls to 2068 equivalents from a Syntax-newsletter ROM-call table
NTSC ULA (6C011) conversion of Ryan's ex-Bill-Miller Spectrum — last three units bought from Mutant Caterpillar
Carl's TS1000→TS1500 conversion: 1500 ROM in a 1000 case with 16K RAM, composite mod, and a NOS TS1000 keyboard
João launched the refreshed Timex Computer World site and detailed the Portugal/Argentina/Poland/Amstrad history behind it
Ryan demoed a ZX Spectrum terminal via FUSE Interface 1, Unix FIFOs, and SoCat dialing into FozTextBBS

Projects discussed: The Bill Miller Collection · "1068" — Enhanced TS1000 · TS-Pico Topics: Hardware projects & new boards · ZX Spectrum · TS1000 / ZX81 / TS1500 · Timex Computer (European: TC2048/3256) · Modems, serial & RS-232 · Newsletters & documentation

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