Timex Sinclair User Group Meeting — July 11, 2022
David Anderson, Adam Trionfo, Carl Miles, Jeff Burrell, Jamie Macbeth, Tim Swenson, Ingo, Ryan Gray, Mark Shek, Jay, Tim, Greg
David Anderson opened with a major archive update: Jack Boatwright shipped two boxes of vintage Timex/Sinclair user-group newsletters and magazines, which David fed through a small duplex sheet-feed scanner. He uploaded 621 issues to archive.org — effectively doubling the site's collection to roughly 1,250 issues — including full runs of The Plotter (Clackamas County T/S group) and large stretches of CATS, SYNC-LINK, and RAMTOP. David traced the lineage of the materials from Rod McGowan and Stan Lemke through the Sir Clive Alive fundraising effort to Don Lambert and finally Jack, who has been the caretaker for 30-plus years. One concrete payoff: the SMUG (Sinclair Milwaukee User Group) video digitizer articles surfaced, including the original schematic and George Chambers' revision. Tim (in New Zealand) has breadboarded the analog section, verified the timings with a scope and an HDMI-to-NTSC converter, and confirmed Jay's recollection that two resistors on the published board need to be swapped; David plans to share his KiCad layout with Tim before sending out a PCB.
Adam Trionfo walked through his two new blog posts retyping the color-graphics programs from a Timex-rebadged ZX Spectrum book, loaded straight into a TAP via the published Spectrum source. The group used his screenshots as a jumping-off point for a long technical aside on the Spectrum's 8×8 attribute color clash, CRT phosphor persistence vs. LCDs, NTSC artifact colors on the Apple II and Atari (and why S-Video kills them), shadow-mask dot pitch, vector monitors (Vectrex, Star Wars arcade), and even Williams-tube CRT memory. Adam also now has a login to push posts to David's Raspberry-Pi-hosted development site, which exports static HTML to timexsinclair.com.
Jamie Macbeth (who teaches x86 assembly at the college level and wants to mix in Z80 on a 2068) joined the conversation; the group recommended Tanenbaum's Minix series and the Onondaga Community College book The Z80 Microprocessor, and traced the Minix → Linux lineage and Linus Torvalds' QL background. Ingo demoed his latest blog post: an external mechanical keyboard for the ZX81/TS1000 that plugs into the expansion port. Rather than the 74LS365 buffer in David's reference schematic, Ingo programmed a single GAL to do the 5-bit tri-state buffer plus the OR gates, using the open-source GALasm toolchain — it worked first try. The group encouraged him to extend it toward a typematic buffer and eventually a PS/2-keyboard front end, pointing to Jack Doheny's EPROM-state-machine PS/2 converter article.
Jeff Burrell described ripping up his earlier interface work and rebuilding it around a Raspberry Pi Pico that boots TS2068, Spectrum, and GW ROM images from an SD card, with interface-one-style bank switching and per-ROM DOS files — sidestepping the now-unobtainium double EPROMs. The group endorsed moving to the new Pico W for ~$2 more so Wi-Fi is on the board even before software exists for it, with FujiNet on the Atari/Apple side cited as the model (modem emulation, virtual SIO drives, web-configured printer emulation). Ryan Gray showed scanned printouts of old programs he wrote — a user-defined graphics editor, a font editor, and a function plotter that used VAL to accept formulas as strings — and described starting to drop in small Z80 routines (via z80asm) to speed up bit decoding into the BASIC display array, using the DEST system variable to find the target variable's address. Closing announcements: next meeting moved to Sunday July 24, then Sunday August 7; the Sinclair ZX World forum has community members (David G., Greg Hardor) typing in programs from the freshly-scanned SYNCWARE NEWS and The Plotter, and David is reaching out to Greg Hardor (Fred Nachbauer's collaborator on the TS1000 Dungeons of Ymir roguelike and high-res work), Evie (of the backpack cart, now ported to the Astrocade), and Jerry Stol/Stano (Slovakia book) to join future meetings.
Highlights
- 621 newsletter issues from Jack Boatwright scanned and uploaded — archive.org collection roughly doubled to ~1,250 issues
- SMUG video digitizer schematic recovered; Tim breadboarded the analog section and verified timings on a scope
- Adam's two new blog posts retype the ZX Spectrum color-graphics book listings for the 2068, with TAPs included
- Ingo built an external ZX81/TS1000 keyboard off the expansion port using a single GAL in place of the 74LS365 buffer
- Jeff's new Pico-based 2068 interface boots ROM images from SD card; group urged adopting the Pico W for Wi-Fi
Projects discussed: UnoDos Topics: Newsletters & documentation · Tape & library archiving (TAP/TZX) · Hardware projects & new boards · Video upgrades (composite, RGB, HDMI) · Machine code, Z80 & assemblers · Pico / modern interfaces (UnoDos, etc.)
Summary generated from the meeting recording; the full transcript is kept in the group's private archive.