TSU Meeting SUNDAY — August 20, 2023

David Anderson, Jeff Burrell, Carl Miles, Gustavo, Ryan Gray, Paul, Mike, Rui, Tim, Mark, Adam

The meeting was dominated by Jeff Burrell's first live demo of the working TS-Pico mass-storage board — the Raspberry Pi Pico-based TS2068 interface developed with Ricardo Calcagno (hardware/PIO) and Gustavo (XROM machine code, hand-assembled on paper from Argentina without access to the actual hardware). Jeff walked through the board: through-hole construction so hobbyists can build it, a 512K×8 flash holding the enhanced XROM/Home ROM, SD-card socket, and provision for 512K SRAM (eyeing CP/M use). He showed booting the 2068, switching I/O to the SD card with SAVE TPI:SDCARD, getting a directory, and loading a 38K Frogger TAP. Gustavo's design uses regular LOAD/SAVE/VERIFY/MERGE rather than a RST 8 hook, and the Spectrum ROM can be paged in from the same board (demoed by Ricardo a few weeks earlier). Target release is November; the Albuquerque group will get pre-production units for beta testing.

A long design discussion followed about folding more functions into the cartridge/expansion ecosystem: incorporating Twister-style Spectrum-bus routing (either as a stub adapter off Jeff's expansion board or a side-edge connector) so Spectrum peripherals like the FDD3 and divIDE could share a single setup, and a newly-defined inter-board protocol using a previously-unused expansion-pin to arbitrate which board owns RAM when multiple cards want the bus. Video and audio came up too: Jeff's video board outputs RGB to a Sega-style mini-DIN (composite sync via LM1881 on the older revision, simplified to passive resistors/diodes on the newer Twister variant), and the group worked through how to expose the AY/beeper sound pin via a 3.5mm jack since the SCART/HDMI path currently drops audio. Carl is breadboarding a SCART harness to feed an Amiga RGB monitor.

Hardware tangents: Ryan killed his 2068's SCLD by hot-swapping a BackBit cartridge; Paul revealed he has two spare SCLDs and two 68-pin PLCC sockets that have sat in a box for ~30 years (likely from the 1995 fire-sale era), which can rescue Ryan's machine. The group discussed how feasible a CPLD/FPGA SCLD replacement would be (small market, but doable — and could finally expose the bright/intensity bit). Rui showed a TC2068 add-on by "Vito" that adds Spectrum-128K compatibility (128K RAM, four ROMs, joystick port, RGB out, audio). Mike's RS-232 board (currently 6850-based, running 115,200 baud) prompted a chat about chip-sourcing trouble — 6850s and 8251s are scarce, Jameco's 8251 stock came from pulled equipment — with suggestions to move to a Pico emulating the UART, or the WD2123/16C550 family.

Announcements and community items: the next meeting is Sept 4 (Labor Day) with guest Steve North, author of TS1000 titles (NFL X Football, Miner's Revenge, the Stapleton-landing game, a 1988 Jamaican-bobsled program) released through Fred Nachbaur. An October meeting will feature Jeff Street (ex-Zebra, OS-64 author). Lewis Floret has set up a Discord channel — Brendan there is working on a "PiKey" keyboard-to-USB adapter and is interested in doing TS1000 and TS2068 versions. Discussion of a Zebra joystick adapter (port 1D, came with game-patching instructions rather than being remappable) for ZX81/TS1000 use, with the British "Command Stick" flying-lead matrix joystick shown as a quirky precedent.

Highlights

Jeff Burrell demos the working TS-Pico board — loads Frogger from SD card via LOAD TPI:
Design discussion to fold Twister/Spectrum-bus routing into Jeff's expansion board
Paul has two spare SCLDs and 68-pin PLCC sockets in storage — can rescue Ryan's killed 2068
Next meeting Sept 4: guest Steve North, author of TS1000 titles via Fred Nachbaur; October features Jeff Street (OS-64)
New Discord channel started by Lewis Floret; Brendan is exploring a 'PiKey' USB keyboard adapter for TS1000/2068

Projects discussed: TS-Pico · FPGA "Advanced 2068" Topics: Pico / modern interfaces (UnoDos, etc.) · Hardware projects & new boards · TS2068 / TC2068 · Video upgrades (composite, RGB, HDMI) · Modems, serial & RS-232 · Joysticks & controllers

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