TRS-80 Pages

Emmulator xtrs: TRS-80 Model I/III/4 Emulator for Unix

xtrs is a Radio Shack TRS-80 Model I/III/4/4P emulator for Unix and the X Window System. It includes lower case, the real time clock, hi-res graphics, serial port, parallel printer, mouse, cassette, sound and music output (requires OSS), 5" and 8" floppy disk drives in single and double density, and even hard disk drives. The emulated floppy and hard disk file formats are compatible with the popular MSDOS-based emulators by Jeff Vavasour, Matthew Reed, and David Keil, and (if you choose a capable enough file format), all features of the original TRS-80 floppy disk controller are emulated. Under Linux, physical floppy disk drives are also supported. Physical cassettes can be read and written too. The user interface is a bit spartan, but it gets the job done.

• xtrs 4.9c (.tar.gz format) (.zip format). Compared with 4.9a, version 4.9c adds watchpoints to the debugger, adds a DOSPLUS compatibility flag to import and export, adds a safety feature to emts, bundles an updated version of the CP/M utilities, and has some internal cleanups. See the change log for details.

• ROM images for Model I/III/4 are available elsewhere on the Web. I do not know the copyright status of these ROM images, and I have no connection with the sites that offer them.
  • Some MS-DOS based TRS-80 emulators come with Model I and Model III/4 ROM image files. These files will work in xtrs too.
  • For Model I emulation, you can also use the LNW-80 ROM image from www.trs-80.com, on the Emulators/ROMs page near the bottom. This image is essentially identical to a Radio Shack Model I Level II ROM except for the message that is printed when Basic starts up.
  • For Model III or Model 4 emulation, xtrs can also use a MODELA/III file as its ROM image. You can download the Tandy MODELA/III from www.trs-80.com. Go to the Model I/III/4 download page, type MODELA in the Description field, select Model IV in the Model field, and press Search. Use one of the files with file type "III", not "DSK".

• For Model 4P emulation, you can use Pete Cervasio's free minimal Model 4P boot ROM, now supplied with xtrs; however, the free ROM can boot only Model 4 mode operating systems, and only from floppy disks. The original Model 4P boot ROM is copyrighted software, but if you own a Model 4P, you can copy its boot ROM onto a floppy for personal use using the instructions and tools in this article, originally published in the Misosys Quarterly 1.2. You can also buy Frank Durda IV's improved Model 4P ROMs from M. A. D. Software.

• Technical documentation is available for the emulated floppy disk file formats used by xtrs and other popular TRS-80 emulators.

• You can always get the latest version of the CP/M utilities for xtrs from their author's web site, but usually the version included with xtrs will be up to date.

• The original xtrs 1.0 was written by David Gingold and Alec Wolman; see their README file. It emulates a Model I with cassette, 48KB of memory, and an uppercase-only display.

If you are writing your own emulator, you are welcome to use my code, in whole or as a guideline. The copyright on the original xtrs code also permits such use. I would appreciate receiving a copy of any improvements you make to the code, however, so that we can release a better xtrs in the future when time permits.