TSU Meeting SUNDAY — June 18, 2023

Richard Booth, David Anderson, Adam Trionfo, Jeff Burrell, Tim Swenson, Gustavo

Guest speaker Richard Booth presented on his 1985 self-published book Applied Sinclair: Subroutines and Programs for the Mathematically Minded — a subroutine-oriented collection of numerical-methods code in Sinclair/Timex BASIC. He walked through the book's structure: vector operations, plane/polar/parametric and contour plotting, special functions, calculus (general-order differentiation), matrices, roots, linear and non-linear regression, differential equations, and a multiple-precision arithmetic chapter plus base conversion. Richard explained that he wrote it after a numerical-methods course and was unimpressed by a competing Apple II numerical-analysis BASIC book; publishers passed, so he ran ~120 self-published copies through a university print shop, advertised in SYNC, and shipped most with a tape.

The presentation turned into a real "40 years later" moment: Adam Trionfo has been typing the programs back in (with Jeff transcribing the listings) and running them, and Gustavo joined from Buenos Aires to tell Richard he had bought the book in 1986 and used its routines for engineering school — Smith-chart polar plots for impedance matching, matrix work, high-res Sinclair plotting. The group dug into why Sinclair BASIC was a good fit for this kind of work: the VAL function for evaluating string expressions (program-generated code), single-keystroke keyword entry, and Sinclair's five-byte floating point giving 9–10 digits of precision versus the typical four-byte / ~7-digit single precision on other home BASICs — enough to make some of Richard's matrix routines actually converge. Trade-offs were acknowledged too: one global namespace, no structured IF/ELSE, GOSUB labels via variables.

A tangent on demo-scene graphics led to a useful explanation of scaled fixed-point integer math (as used on the Apollo Guidance Computer) as the way to get fast graphics without floating point. Richard also walked through his post-book career — CMU, Maryland, Westinghouse, Lehigh, IMEC Belgium, AT&T Bell Labs, Lattice, Empyrean, and now silicon-photonics IC design at Cisco — which led to a short technical detour on SAR vs. delta-sigma ADCs and on optical phase modulation for fiber.

In the back half the group covered other community items: Jeff Burrell's FPGA board for the 2068 (VGA output by snooping the video memory, plus a UART running at ~3 Mbaud for fast file transfer to a PC); a survey of similar-era scientific books (the 1984 Numerical Analysis for Apple/Commodore/TRS-80, Wallock's TS1000 Statistics, Firth & Sparks's interfacing book, Celestial BASIC); BASIC compilers for the 2068 (NovaSoft's "Time Machine" / HiSoft BASIC port, and Simon Goodwin's ZIP compiler); the groups.io storage cap and the fact members can't currently delete their own attachments; David's plan to disperse extra hardware (including a rare UK ZX81 5.25" floppy system from James March, and 38 shrink-wrapped copies of Frogger for the ZX81) via an opt-in mailing list rather than eBay; Michael's in-progress RS-232 board using the Motorola 6850; and Fred Nachbaur's high-res ZX81 game Dungeons of Ymir and his SyncWare News magazine. Upcoming guest plans include Jeff Street (author of OS64 for Zebra Systems) and possibly Cesar, the author of the ZXSpin/Zsorex emulator. David also previewed the next "Timex Connection" episode with João, where memos show the TS1500's Spectrum-style case and keyboard idea actually originated from Timex Portugal, and recapped the Timex–Poland deal that shipped large quantities of TS2068s and FDD-3000 disk systems to Poland after Amstrad bought Sinclair.

Highlights

Guest Richard Booth presented on his 1985 self-published math/numerical-methods book Applied Sinclair.
Adam Trionfo and Jeff are re-typing the book's programs in 2023 and running them on real hardware.
Gustavo joined from Argentina to say he used Richard's book in 1986 for engineering-school Smith-chart and matrix work.
Deep dive on why Sinclair BASIC fit the book: the VAL function and the 5-byte floating point giving 9–10 digits of precision.
Jeff Burrell showed his FPGA board for the 2068 — VGA output by snooping video memory, plus a ~3 Mbaud UART for fast PC transfer.

Projects discussed: FPGA "Advanced 2068" Topics: BASIC programming · Books & manuals · TS1000 / ZX81 / TS1500 · Hardware projects & new boards · Modems, serial & RS-232 · User group meetings & events

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