New Unofficial NEWDOS/80 Zap

Shawn Sijnstra was kind enough to supply a NEWDOS/80 Zap from Northern Bytes Newsletter which will correct the usage of the CLEAR command.

Unzapped, the CLEAR command does not honor any HIMEM setting. Tony Domigan developed a zap for the Model III which would cause the CLEAR command to clear from 5200H to HIMEM instead of 5200H to FFFF. Using the command CLEAR * will clear to FFFFH.

The added zap can be found on the Unofficial NEWDOS/80 v2.0 ZAPS page.

TRS80GP v2.4.4 Released

TRS80GP has been updated to v2.4.4. Release Notes:

New Features:

  • (WIP) Track dump in Disk Debug (including HFE)
  • (WIP) Corvus hard disk emulation
  • Raspberry Pi 32-bit (Raspian) and 64-bit (Ubuntu) versions.
  • MX-70 printer emulation (-mx70 or -p :mx70)
  • Additional views for Disk Debug window including a diskette summary.
  • Disk debug window has additional views to show IDAM/DAM and disk summary.
  • Linux GTK version added icon for the main window.
  • Bus trace details interrupt status/mask bits for Model III.

New Command Line Options:

  • -mmu16 n to control number of extension bits of 68000 MMU (0 .. 3).
  • -memgap16 to create gaps of unmmaped 68000 memory.
  • -nld to suppress loading lower-case driver in Model I cassette boot.
  • -wtfs N to update window title at most every N frames on LINUX


  • Authentic mode faster by redrawing only changed lines of display.
  • NEWDOS/80 can now format .imd format diskette images.
  • Orchestra-85 sound no longer noisy.
  • Stop crash when flag register checkbox clicked on windows.
  • Have entry point breakpoint of /CMD file loaded under a DOS trigger promptly.
  • DREM hard drive loader uses .DSK or .dsk for data filename (Linux fix).
  • EMU hard drive blank tracks now same as ext2emu.
  • Formatting more than 128 tracks works for HFE and IMD.
  • Disk ASCII dump works on Super Utility (removed assert()).
  • HFEv3 floppy format will warn and not load (version 3 not supported).
  • IMD floppy format correctly reading/writing head/cylinder maps.
  • Floppy loading improved to fix memory leaks and allow larger images.
  • Memory leak fixes for cut/paste and bus tracing.
  • Model I RS Doubler detect modified so Super Utility doesn’t trigger it immediately.

Visit the TRS80GP Web Page for the download and information, or here for the emulator.

September 2021 Issue of TRS8Bit Released

Dusty has released the March 2021 issue of the TRS8Bit newsletter. Here’s what he had to say:

In this issue, E.T. Fonehume has a BASIC one-liner to run Kaprekar’s Constant. Maurits Van Wijland upgrades a M4 from 16K to 64K in a very detailed article. Lawrence Kesteloot has an upgrade on TRS80-TOOL. ‘Noel’s Retro Lab’ reviews a vintage chip tester in kit form. Ian Mavric sorts out ‘contact fatigue’ on a M3/4 bus and improves a heavy duty power supply. He also concludes his series of building the ‘Super Micro Mk 2’. Pascal Holdry brings us news from France and finds there’s a new type of enthusiast. Harold Finch sets us another brain-teaser. Paul T Metcalf shows a M1 using an MDHI monitor. There’s also details of running trs80gp on a Raspberry Pi 400 (nothing less than a worlds first), a look at some of the Ebay bargains from the last 3 months and there’s a bargain for someone in the ‘For Sale & Wanted’ feature. There’s the usual feature of ‘The Way We Were’ and ‘Assembler Bytes Back’ and to end this veritable ‘feast-of-fun’, the final details of this year’s competition. It’s a must-read for any Tandy/TRS-80 enthusiast!

It can be downloaded from his web site.

TRS80-Tool Cassette Utility Updated to v2.10

Lawrence Kesteloot has updated his amazing TRS-80 Tool cassette utility to v2.10. The change is the addition of a “–entry” option which will permit you to designate entry locations when disassembling a file. Since the disassembly routine logically determines when something is code and something is an ascii string, and shows the string if there is one; there was an issue when a program relocates itself. In that case, the disassembler routine assumed everything was ASCII because it wasn’t being executed. Now, if you get a bad disassembly, you can set an “–entry” option to tell the disassembly routine to start processing that location as code.

The standalone can be found on v2.10 can be downloaded there or right here for Windows / Linux / Mac.

August 28, 2021 – Site Updates

  • The How to Open your TRS-80 page has been updated with step-by-step instructions to open and replace the powers supply of a Model 4P.
  • While I can’t seem to override every bit of CSS being injected by wordpress, I have managed to hide enough of it to make the pages on this site somewhat printable – there is just a lot of space before and after.
  • I found out that I have a pretty tricked out Model 4 … until I promptly broke it. Then I went to test out a 4P that worked when last powered on, and got “SEEK ERROR” on a perfectly good DOS. Not good luck going on.

Newsoft’s 4/4D/4P Power Supply Updated to v2.0

Jay Newirth is now selling v2 of the Model 4/4D/4P power supplies using modern day components!

This iteration has the power supplies mounted to the floor of the case, but with only a small board attached to the drive bay. This is particularly useful for those people, like myself, with a Model 4 that has the old style (plastic) drive bays, as there is not enough clearance for Jay’s 4/4D/4P v1.0 power supply to fit.

You can find it at the NewSoft Store.