TSU Meeting SUNDAY — December 21, 2025

David, Peyton, Gustavo, Carl, Ingo, Ryan, Joe

The last meeting of 2025 opened with a seasonal-programming challenge. Peyton shared two holiday listings he typed in from the December 1983 issue of Sync-Set (vol. 2 #11) — a 2068 program that draws Santa and his reindeer while playing a tune, and a TS1000 Christmas-tree program — plus his entry for the Vintage Compute Challenge: a BASIC snowflake plotter that he iterated on (with help from Gemini) to be as compact as possible. David showed a related "snowflake" listing from the Capital Area TSUG newsletter that plots one quadrant and rotates it three ways (faster than a circle command), with a 1.2× aspect adjustment for the 2040 printer's non-square pixels.

Carl walked through the two TS1500s he's repairing for Mowgli, showing the differences between an 8514-dated full-size board (eight 4116 RAMs, the LS244 buffer) and an 8630-dated "short board" / low-cost TS1500A (two RAMs, resistor packs in place of the 244, smaller SCLD that supports the 7-bit refresh the 4416s need). Gustavo (Argentina) added context on the Portugal production run, NTSC/PAL-N compatibility, and Timex/TI parts sourcing in '85-'86. Both keyboards had broken tails — one cracked under tape that had been used to fold the ribbon, the other at the motherboard connector — and Carl is replacing the membranes (the modern ones are clear plastic and the 1500's metal overlay uses tabs, not adhesive, so the new "angle-cut" membranes are the ones to buy). On video he's converting them to composite using Claudius's single-transistor design, but the picture is dim with a 270 Ω load — switching to 100 Ω was suggested, and Stuart's CX composite-converter board (≈$25) is the fallback.

Ingo joined with his v0.2 "1068" motherboard (Carl's enhanced TS1000 board for the Kilo-Z case) and is sorting parts for a minimal build — emphasizing the board's value as a drop-in for people unwilling to mod an original issue-1/issue-3, as long as Charlie Ingley's ULA replacements and Z80s remain available. Ryan demoed his redesigned low-profile mechanical keyboard PCB (Gateron/Cherry MX low-profile, ribbon header moved two rows inward to clear the case's keyboard cradle, DuPont headers for flexible mounting) and shared UV-printed key-cap test prints from Louis Blake at 3DKeyCap in Montreal — black caps with white/red/grey printing, much more wear-resistant than his water-slide decals, and a candidate for a future TS2068 set too. He's also exploring a wider 60-key layout (full spacebar, dual shifts) and a standalone USB keyboard variant for emulator users.

Peyton then revealed — to general surprise — that he has been quietly modeling a 3D-printable TS2068 case in SketchUp from caliper measurements: the exterior, all back ports done, working on the interior posts next. Discussion turned to splitting the model (the 2068 is 373 mm — too long for a 256 mm P1S bed even at an angle), Joe's "butterfly" inserts for invisibly joining printed halves, Bambu Lab printers (P1S, H2D) as the practical recommendation, and a suggestion to design the rear panel as a swappable insert so future motherboards can change the port layout without reprinting the case. The meeting closed on a wide-ranging "modern 2068" discussion — Jeff's Pico-based video board (regular $4 Pico, all Timex modes plus ULAplus and independent 64/80-column text modes useful for CP/M), HDMI via a Pi instead of a Pico, the Yamaha YM2149 as a still-available AY-3-8912 sound substitute, FPGA AY clones, and even putting a SID alongside for kicks. Next meeting: Monday January 5th, 9pm. Adam is in Austin with family.

Highlights

Peyton typed in two holiday listings from Sync-Set Dec '83 and submitted a BASIC snowflake to the Vintage Compute Challenge (iterated with Gemini for compactness)
Carl compared an 8514-dated 8-RAM TS1500 board against an 8630-dated 2-RAM "low-cost" TS1500A short board, with Gustavo adding Portugal/NTSC sourcing context
Ingo began populating his v0.2 "1068" motherboard — Carl's enhanced TS1000 board for the Kilo-Z case
Ryan showed a redesigned low-profile mechanical keyboard PCB and UV-printed key-cap tests from 3DKeyCap (Montreal), replacing the water-slide decals
Peyton revealed a 3D-printable TS2068 case he's been modeling in SketchUp from caliper measurements

Projects discussed: "1068" — Enhanced TS1000 · FPGA "Advanced 2068" Topics: TS1000 / ZX81 / TS1500 · Hardware projects & new boards · TS2068 / TC2068 · Repair & restoration · Video upgrades (composite, RGB, HDMI) · BASIC programming

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