Timex Sinclair User Group Meeting with European Friends — March 20, 2022

David, Will Column, Carl Miles, Adam Trionfo, Bruno, Stewart Newfeld, Tim, Jeff Burrell

The group hosted Will Column, a former Timex Computer Corporation engineer who worked in the software group in 1983–84 (under Scott McCourt, alongside ex-Burroughs programmers Dave Boyle and Lon Hildreth). Will walked through what he actually wrote — most memorably the few-instruction TS1500 cartridge-detect-and-autostart routine. He had to scavenge bytes from the boot-time memory-test code because the ROM had only two non-contiguous free bytes; the trick was that with no cartridge installed, pull-up resistors made the data bus at $2000 float high to FF, so a decrement of an opcode 01 (LD BC,nn) at the cartridge's start would land on zero with a cartridge and not without, gating a jump to $2000. Will confirmed he didn't work on the TS2068's cartridge system (AROS/LROS); that was likely the former-Burroughs comp-sci side of the group.

Carl Miles drove much of the technical discussion around his TS1510 cartridge-interface clone — he's built the PCB and is studying dumped cartridge code (States and Capitals, Chess, Super Math; Flight Simulator is still the only undumped one of the four) so he can author new cartridges, hoping eventually to put TS1000 software like 3D Monster Maze onto cartridge. David and Carl noted the TS2068's ability to run BASIC programs straight from a cartridge (Tom Woods's database was cited) as a feature with no real contemporary parallel. Carl also walked through the Portuguese TS1500 variant whose late motherboard revision drops six RAM chips (moving to two 4416s), removes the 74LS244 buffers (jumpered with resistors), and eliminates the −5V/+12V switching regulator entirely — a clearly cost-reduced design from the Timex-Portugal era.

Bruno (originally from Portugal, now in the US) introduced himself as a long-time collector of Timex history and contacts. He has corresponded with former Timex SVP Lou Galley (now retired and out of contact), R&D head Victor Schiff, and industrial designer Gary Grimes, and obtained written confirmation from Timex legal that all Timex-authored software is now public domain. He also has the rare transparent TS2068 prototype from Galley's personal stash, and reminded the group about Dom Ding Dang's Twister board, which lets Spectrum interfaces work on the TS2068. The Parker Electronics CC02 "Command Center" was discussed — a carrier-HVAC controller built around a fire-sale TS1500 plus a custom interface board, almost certainly with its own ROM mapped at $2000.

On community housekeeping: the original Yahoo TS-2068 group messages were never migrated into the current groups.io list (an archive does exist on archive.org), and nobody on the call could name the current groups.io owner, blocking admin features. Stewart Newfeld (Zebra Systems) shared his aerospace-test-equipment background. The group floated future meeting topics: Bruno presenting more of his collection, and Tim and Jeff Burrell talking about modern Z80 workflows; Tim's write-up on converting Spectrum assembly to the TS2068 was singled out as especially useful.

Highlights

Will Column reconstructs the TS1500 cartridge-autostart routine — exploiting the data bus floating high to FF when no cartridge is present, with only two non-contiguous free bytes in the ROM to work with
Carl Miles is building TS1510 cartridge-interface clone boards and reverse-engineering the four Timex cartridges; Flight Simulator is the only one still undumped
Bruno has written confirmation from Timex legal that all Timex-authored software is public domain
Carl walks through a late Portuguese TS1500 motherboard revision: 2 RAM chips instead of 8, 74LS244 buffers jumpered out, switching regulator removed
The original Yahoo TS-2068 group messages never made it onto groups.io — only an archive.org copy survives, and the current groups.io owner is unknown

Projects discussed: TS1510 Cartridge Interface Clone Topics: Cartridges, EPROM & dumping · TS1000 / ZX81 / TS1500 · TS1510 cartridge interface · TS2068 / TC2068 · Machine code, Z80 & assemblers · Timex Computer (European: TC2048/3256)

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