Timex Sinclair User Group Meeting — November 7, 2022

David Anderson, Jeff Burrell, Tom, Stuart, Tim, Adam Trionfo, Ryan Gray, Carl Miles, Ingo

Adam, Ryan, and Carl recapped the Albuquerque in-person meet — show-and-tell of mini Dig Dug/Q*Bert cabinets, Ryan's Pi-400 emulation rig, and an on-the-bench tweak of a TS2068's color-fringing trim cap. A side discussion covered keycap-sticker sets from 4Keyboard (ZX80/ZX81/Spectrum layouts) and tactile micro-switch ZX81 keyboards sourced via Ginger Electronics in Germany.

Jeff Burrell demoed his cross-platform Python TAP-to-Cart tool — a command-line version and a Tkinter GUI wrapper that take a TS2068 TAP file, read a control file of cartridge parameters, and emit an AROS-format DOCK image. Ryan ran Jeff's tool on his Pi and used it to turn his programmable-font BASIC program into a working cartridge image; because cartridge code runs from ROM (lines are copied piecewise into RAM to interpret), he had to detect the DOCK environment and move RAMTOP down to stash the machine-code font and font-offset byte in high memory instead of a line-1 REM. The group noted that DEF FN-heavy programs are hard to run from cartridge because Sinclair BASIC scans the whole program top-down at every call. David also reported that Jim Marsh joined the previous Sunday's meeting and contributed scans/uploads of TreeForth — an 8K Forth replacement ROM for the ZX81/TS1000 with a 96-page manual — and noted its striking similarity to the UK "Husband Forth" product.

Tom walked through his Common-Lisp interpreter for Sinclair BASIC: he has the REPL, PRINT with TAB-column tracking, and is adding GOTO/LET/INPUT next; he can also compile it as an executable that takes a script and returns a value, so it doubles as a scripting language. He asked how to render the block-graphic characters in a plain terminal; Ryan explained that the ZX81/TS1000 has no real graphics layer — PLOT/UNPLOT just substitutes one of the block-graphic characters in the character cell — and the group suggested Unicode block elements as a starting point. Stuart and Tim (joining from New Zealand) introduced their "DX Printer Shield" — an Arduino-Uno shield they designed in EasyEDA that drives the Timex 2040, Alphacom 32, and original Sinclair silver-paper printers; Tim's Arduino library ships Hello-World, character-set, and bitmap-print examples (an Arduino-logo print was the first graphic), and the shield exposes stackable headers and a Qwiic/STEMMA I2C connector for sensors and a real-time clock. One more board spin is going to New Zealand for testing before a community batch. Stuart also previewed a ZX81-shell USB keyboard board (Pro Micro + Atari joystick port) and a planned breakout-bus carrier for re-implementing the projects from the 1980s ZX81/TS1000 interfacing books.

Ingo showed his hand-built Eurocard Z80 microprocessor trainer: two Z80 PIO cards giving four parallel ports (jumper-selectable I/O addresses), plus a piggyback debug board that latches the accumulator and flags register to 7-segments on every M1 cycle, triggered off RFSH+MREQ via a 74LS32. The plan is to wire up his mechanical ZX81 keyboard and single-step the ZX81 ROM's keyboard-scan routine from an EPROM. The group riffed that with ROM+RAM+stack it could become a proper Z80 chip-tester for the dodgy AliExpress Z80s now in circulation. David reported on the Timex Portugal 3" floppy archiving project: Neil sent him a stack of Hitachi compact-floppy disks and bare drives, Joe Vandy Zandy imaged them with both CPCDiskXP and a Greaseweazle (per-track flux), David ran the resulting images through tomato (under Wine) and pulled ~50–60 programs — including Star Trek, several BBS programs, CP/M 2.2 disks for the FDD3000, Zebra disks, and CATS and Cleveland user-group library disks — all uploaded to archive.org. Carl noted that Kryoflux/Greaseweazle flux dumps also preserve copy-protection tricks like half-step tracks and let you write physical disks back. To close, Adam showed off Chris Smith's Spectrum-ULA book (the basis for the Harlequin clone David has built) and Tim posted Grant Searle's ZX81+38 / +35 discrete-logic ZX81 reproductions. Next meeting: Sunday Nov 20, 2 pm Eastern.

Highlights

Jeff Burrell's Python TAP-to-Cart tool (CLI + Tkinter GUI) demoed; Ryan got his programmable-font BASIC program running as an AROS cartridge by moving RAMTOP and stashing the font in high memory
Stuart & Tim's "DX Printer Shield" — an Arduino-Uno shield in EasyEDA that drives Timex 2040, Alphacom 32, and Sinclair printers — printed Hello World and a bitmap Arduino logo; one more board spin before a community batch
Tom's Common-Lisp Sinclair-BASIC interpreter has REPL + PRINT with TAB columns working; group steered him toward Unicode block elements for the block-graphic characters
Ingo's Eurocard Z80 trainer with dual-PIO parallel-port card and an accumulator/flags debug latch piggyback triggered off RFSH+MREQ — heading toward single-stepping the ZX81 keyboard-scan ROM routine
David recovered ~50–60 programs (Star Trek, BBS, CP/M, CATS/Cleveland library disks) from Timex-Portugal 3" Hitachi floppies imaged by Joe Vandy Zandy with CPCDiskXP and Greaseweazle; all uploaded to archive.org

Projects discussed: TAP-to-Cart — TS2068 Cartridge Conversion Topics: Cartridges, EPROM & dumping · Hardware projects & new boards · Tape & library archiving (TAP/TZX) · Printers & plotters · TS1000 / ZX81 / TS1500 · Disk & floppy systems (Larken, AERCO, Oliger)

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