TSU Meeting MONDAY — April 3, 2023
David Anderson, Adam Trionfo, Robert Fischer, Carl Miles, Gustavo, Michael Druckenmiller, Joe, Tim Swenson, AJ, Claudio
Guest speaker Robert Fischer — a retired middle-school band director — walked the group through the TS1000/TS2068 gradebook program he wrote in the 1980s. He hit three problems all the contemporary gradebooks shared (display, capacity, speed) and worked around each: a two-screen design (46 students per class screen, 68 grades per student screen) instead of constant scrolling; storing grades first as 3-byte strings, then as single bytes (0–255), which jumped storage from ~50 to 232+ students on the TS1000 and over 1,100 on the 2068; and moving averaging and screen printing into machine code by reading Tom Woods' published Profile source, dropping a 40-second update to about a second. Bob also published five issues of "Extensions," a newsletter of patches and enhancements for Tom Woods' Profile 2068 database (widening the menu to 17–18 lines, fixing the "Search Complete"/blank-line printout, cursor wrap, name reversal, file append, etc.); RMG Enterprises later picked up the Plus 5 version. He also wrote small jumble, cryptogram, and crossword helper programs, and recommended Mike Singleton's Lords of Midnight as a memory-packing inspiration.
Carl Miles reported on his ongoing TS1000/ZX81 composite-video experiments. He tried Stewart's ZX8-CCB composite mod and a 555-timer composite mod in two different machines; neither gave a clean picture (cursor smear on the top, no adjustments on the 555 board), and cascading one into the other didn't help. He then swapped in a VLA-81 ULA replacement and walked through its two DIP switches (level select; back-porch on/off to emulate the 158/174 or the 210 ULA). The best image he got was actually the RF output with the VLA-81 fitted; he suspects he blew a gate on the ZX8-CCB by initially running the VLA-81 with both switches off (high output level). He's now leaning toward Claudius's earlier theory that the worst-affected machine just has a far-gone ULA.
Gustavo (Buenos Aires) asked whether any official SCLD timing documentation exists for the TS2068 — interrupt-to-vertical/horizontal-pulse counts, scan counters — to cross-check measurements he's taken with a scope. The group pointed him at the Timex Technical Manual's video section and suggested cross-referencing the Portuguese TC2068/TC2048 (same SCLD, jumper- and crystal-selectable for 50/60 Hz), noting that PAL/NTSC versions use a different main crystal and a different LM1889 tank-circuit crystal. New attendee Michael Druckenmiller introduced himself: ex-Navy aviation electronics tech, programmed a surplus IBM Selectric I/O console from a TS2068 (ASCII-to-solenoid translation table, salvaged Burroughs backplane connectors), and has ported an FFT routine to Timex BASIC, posted on houseofmyrrh.org. Claudio joined late from Brazil with his original Microdigital TK system and a tour of the South-American Sinclair/MSX clone scene (TK82C, TK85, TK90X, TK95, HotBit MSX, and Prologica's CP400 — a TRS-80 CoCo clone housed in a TS2068-shaped case); he also showed a brand-new MSX cartridge with an extra VDP made by Victor Trucco, the engineer behind TBBlue / ZX Spectrum Next.
The round-robin on memorable peripherals turned up: Joe's Bytebak 8-bit I/O relay board (used for an eight-channel Christmas-light display) and its companion A/D converter, plus the Bytebak Hunter battery-backed RAM/ROM swap module that sits at 8–16K; AJ's Memotech stack (64K RAM, serial, Centronics, HRG, blue keyboard), ZX Printer, Bytebak real-time clock used with Kurt Casby's CAS board to timestamp the 2040 printer, and John McMichael's TS2068 software bundle driving the Commodore 1520 pen plotter and Okimate 10/20 color printers, plus a Larken disk for the 1000 he's never hooked up; Tim Swenson's MTD Software (Mike/Tim/Doug) calculus program from 1984–85 (BASIC plus inline ML, sold legit with a business license); a Gladstone Electronics / Dean Electronics keyboard kit; and an extended Adam/Carl chat about TS1000 keyboard overlays (Filesixty Buttonset, Second Base). Adam gave the Albuquerque update — typing in Dan Tanberg's never-archived Star Blasters on real hardware, and ongoing troubleshooting of the BackBit cart's .p-file loader (Evie has issued a partial patch). David flagged that Paul Holmgren has Basil Wentworth's stash of unpublished Syncware News articles, which he plans to route to Tim Swenson's ZXZine. The next meeting was set for April 16, 2023, with manual author Chuck Dierung as guest.
Highlights
- Guest Robert Fischer details his TS1000/TS2068 gradebook: 1-byte grade storage pushed capacity past 232 students; machine-code routines from Tom Woods' Profile dropped class-average updates from 40s to ~1s.
- Bob recaps his five-issue 'Extensions' newsletter for Profile 2068 (later picked up by RMG Enterprises as the Plus 5 version).
- Carl Miles compares ZX8-CCB and 555-timer composite mods against a VLA-81 ULA replacement; best picture so far is RF out with the VLA-81 fitted.
- Claudio joins from Brazil with a tour of Microdigital TK clones, the Prologica CP400, and a new Victor Trucco MSX-VDP cartridge.
- Next meeting April 16, 2023 — Chuck Dierung, author of the TS1000 and TS2068 manuals.
Topics: TS2068 / TC2068 · TS1000 / ZX81 / TS1500 · BASIC programming · Video upgrades (composite, RGB, HDMI) · Utilities & applications · Hardware projects & new boards
Summary generated from the meeting recording; the full transcript is kept in the group's private archive.