The July 6 meeting was given over largely to guest David Stephenson, the Australian developer behind the ZX81 Keyboard Adventure blog, who joined to walk through Zevious, his ZX81 reimagining of the arcade game Xevious, released about four weeks earlier. He wrote it in C with z88dk, developed in the Geany IDE on Linux, and tested on a Minstrel 3 alongside the EightyOne emulator, fitting the whole game into 16K. The technical heart of the talk was his display scheme: rather than clear and redraw, he runs three display files — a master map plus two buffers that swap in and out — so the background scrolls every three frames while enemies move every frame, with a full redraw on every eighth frame (ten on NTSC, which runs slightly slower). He compressed levels with run-length encoding to leave roughly 4K for game logic after the C runtime, and tied timing to the frame counter to avoid the screen tearing a clock-based approach had caused. Zevious has drawn about 400 downloads, more than either of his earlier titles, and a Chroma 81 color version was produced quickly by Kelly Murta on the Sinclair World forums.
Stephenson traced his path from a childhood ZX81 in Australia through a Raspberry Pi–based emulator build and the full-size USB keyboard for the ZX81/TS1000 that first drew attention to his blog. His Halloween maze game Tut Tut, written for Paleotronic magazine, began in Spectrum BASIC, was rebuilt in C for the ZX81 through Cronosoft, and then spread to the RC2014, Jupiter Ace, Commodore PET and VIC-20; a Minotaur-themed sequel, Minos Knossoss, followed on the ZX81. His next project is a PET port of Zevious with Dave Curran of Tynemouth Software. Asked what surprised him about the ZX81, he returned to a theme that ran through the night — that the machine is far more capable than its calculator-with-a-bad-keyboard reputation, and that its constraints are exactly what make wringing a real game out of it worthwhile.
Joe VandeZande showed hardware David had sent for the Chicago VCF Midwest show. One ZX81 carried a composite-video modification built around a 555 timer adding a back porch, tapped off pin 16 of the ULA, along with added keyboard circuitry and a beeper chip he is still reverse-engineering. He also displayed two unusual external keyboards: one with only three rows, its top row switching between digits and letters via a toggle and using an LM3915 dot-mode bar graph as a tape-loading indicator, and a second hand-painted unit with rounded key switches, a 3D-printed space bar he had to build a custom mount for, and a Christmas-tree bulb serving as the power light.
John Stroebel revealed that he is a developer on the EightyOne emulator, working with Paul Farrow, with recent work adding AY sound and speech support. He had also revived two of three TS2068 BASIC programs from an Asa Gordon paper, correcting OCR damage in dense code carrying more than 200 BASIC variables. He described EightyOne’s wave-file loading interface, which he uses to send and capture data to and from his real ZX81 hardware, and its on-screen video-signal annotations showing sync pulses and the back porch; the emulator is built on a 2002-era Borland C++ Builder.
Ryan Gray shared photos from a stop at the National Video Game Museum, walking the group through vintage development systems, a wall of consoles, and a Fairchild Channel F display, with a digression on Zircon — the joystick maker that later became better known for stud finders.
On housekeeping, the group noted it has long since passed its hundredth meeting and floated marking the 128th — “all eight bits” — as a milestone celebration a few months out, with a running joke about whether 127 or 128 is the truer byte.