Skip to content

TSU Meeting SUNDAY — July 19, 2026

David, John, Greg, Tim, Ryan, Carl, Jeff, Tom, Johnny Red

John demoed his TS2068 extended-colour (8x1 attribute, high-colour) image viewer, running in Fuse and on a real 2068 loading from the TS-Pico. It started from the Lloyd Drager example code in David's TS2068 machine code book (John fixed OCR errors in the published listing against the original source on archive.org). The viewer loads the attributes into a RAM buffer while the screen is blacked out, then reveals the image with machine-code wipes (left/right, curtains, vertical blinds). A TS-Pico slideshow version shows many images with random wipes. The images were made with the Retro Pixel Converter, with saturation, contrast and gamma tweaked. The group was amazed at how much colour the mode can show, and David plans to run the demo at VCF Midwest. David also mentioned Lou Champagne, who wrote ZX81 MIDI-interface articles (using a 6850 ACIA) for the Toronto user group newsletter and turns out to be an '80s Toronto synth musician.

Greg showed an ESP32 "cheap yellow display"-style board that his ZXpand+ triggers over serial to play audio, using a 3.3V/5V level shifter. He also floated an idea for colour images on the ZX81 using Chroma 81's per-scanline colour together with UDGs. David pointed to Greg Harder's YouTube channel, where he posts ZX81 high-res and Chroma 81 demos, including a colour conversion of Dan Tanberg's Time Blasters. Tim is scanning a 300–400 page ViewCalc example book and writing a Z80 assembly troubleshooting guide. He wants a simple, pure-assembly tutorial on WRX high-res graphics and plans to learn AY-chip programming from assembly.

Most of the meeting was a long discussion of TS2068 video and hardware. Ryan suggested a modified ROM, swapped in by the TS-Pico, that would make BASIC's PLOT/DRAW and SCREEN$ work in high-colour mode. John confirmed that pixels sit at 4000h and attributes at 6000h, and the OS-64 cartridge's reuse of the unused attribute areas came up. Jeff described the Pico video card: all the standard TS2068 modes, ULA+ (in theory 256 colours using the bright/flash bits) and a true 80-column text mode. He also covered the possibility of firmware drawing commands sent over an I/O port and why moving to an RP2350 makes sense, and explained why video-RAM contention is built into the SCLD. Carl proposed a modern replacement board that fits the original 2068 case: a Pico/CPLD SCLD substitute with better video, and maybe USB keyboard output. That led to Jeff's 2060 design, which can also run standalone and be adapted to fit a 2068 case. Carl will mock up the original board's dimensions, and David will scan a bare 2068 board for him and send it to the list. The discussion continues at the first-Monday meeting on August 3.

Highlights

  • John's high-colour (8x1 attribute) image viewer and slideshow with machine-code wipes, running on a real 2068 from the TS-Pico
  • OCR errors in the published Lloyd Drager high-colour example found and fixed against the original source
  • Discussion of a modified ROM, swapped in by the TS-Pico, so BASIC drawing commands work in high-colour mode; ULA+ and 80 columns on the Pico video card
  • Proposal for a modern replacement 2068 motherboard (Pico/CPLD SCLD substitute) based on Jeff's 2060 design; Carl to mock up the board, David to scan a bare board
  • Greg's ESP32 display triggered from a ZXpand+ over serial; Tim scanning a 400-page ViewCalc example book

Projects discussed: Retro pixel converter · TS-Pico · FPGA "Advanced 2068" Topics: Video upgrades (composite, RGB, HDMI) · TS2068 / TC2068 · Hardware projects & new boards · Machine code, Z80 & assemblers · TS1000 / ZX81 / TS1500 · Pico / modern interfaces (UnoDos, etc.)

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