August 23, 2023 – BOOT/SYS of Model I NEWDOS/80 v2.0 Disassembled

A commented disassembly of BOOT/SYS of NEWDOS/80 v2.0 for the Model I has been added.

As noted on the page, two things really struck me about how that sector was programmed. The first, is that it was broken into different parts – one which handled DISK I/O (including polling the FDC and reading data) and one which used the data which was read. By handling it this way, Cliff simply used the EXX command to swap out the registers wholesale, depending on which set of routines he was using. With this, he only used the PUSH command 3 times in the entire routine! The other thing was that since the Model I has a memory location for accessing the Floppy Disk Controller instead of ports, manipulation and testing of the controller data could be done in 1 opcode instead of 2.

August 20, 2023 – SDLTRS II Updated to v1.2.28

Jens Guenther has updated his fork of the SDLTRS Emulator to version 1.2.28. Changelog includes:

  • Added XTRS feature to fake year for TRS-80 clock-of-day.
  • Added 5″ / 8″ disk size switch for Percom doubler and clones.
  • Added debug commands to load and save the emulator state.
  • Added option to set the action for Z80 HALT instruction.
  • Added option to pause the emulator at startup.
  • Fixed 6845 CRTC cursor redraw issues.
  • Fixed bugs in mouse selection.
  • Fixed AlphaTech SuperMem 32K bank switch.
  • Fixed loading of state file for TRS-80 clones.
  • Fixed more bugs and internal improvements.

You can download the most recent SDLTRS II from the Gitlab page: and remember to download SDL (links on the Github page). If you are just looking for the Windows x64 copy, you can download a combined executable/source/SDL v2 package here.

August 9, 2023 – Update to Software Archive Search Page

So … that Molimerx catalog is something, isn’t it. It’s not so much a catalog in my view (because there are no prices except for the last 3 pages) and more of a product guide, albeit one which rarely identifies the author.

To the extent that a catalog entry can be matched to software, I plan on breaking out the product descriptions into viewable JPGs. Those will appear on the Archive Search page with a little speech bubble …

To see one in action you can search either for Monitor 3 or Mysterious Adventure.

July 28, 2023 – 12MB Hard Drive Manuals

Pascal Holdry has scanned a few 12MB Hard Drive Manuals:

Title: 12-Meg Hard Disk Drive Owners Manual
Publisher: Tandy
Year: 1982
Size: 712,197
Pages: 56
Title: 12-15-Meg Hard Disk Drive Service Manual
Publisher: Tandy
Year: 1983
Size: 20,565,393
Pages: 285
Title: 12-Meg Hard Disk Drive Service Manual
Publisher: Tandy
Year: 1983
Size: 2,837,779
Pages: 77

Thank you Pascal!