Tim Mann's TRS-80 Pages

Business card from 1981

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xtrs: TRS-80 Model I/III/4/4P 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.

Also check out sdltrs by Mark Grebe. It is a TRS-80 emulator for Linux, Mac OS X, and Windows based on xtrs. All three versions of sdltrs have a text-based menu UI that makes it easier to insert/remove emulated floppy disks and tapes and to change other settings. The Mac version also has a nice native Mac GUI.

xtrs downloads and resources

• xtrs 4.9d (.tar.gz format) (.zip format). Compared with 4.9c, version 4.9d adds a keybinding help window (press F11 to see it), adds a feature so that NEWDOS/80 boots up knowing the date and time, fixes a bug that prevented -delay and -autodelay from working when compiled with newer versions of gcc that optimize better, and also includes a few more obscure bug fixes and 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.

• Alternatively, for Model III or Model 4 emulation, xtrs can use a MODELA/III file as its ROM image. This is not identical to a real Model III/4 ROM, but is close enough that almost 100% of TRS-80 programs will work with it. The LS-DOS 6.3.1H operating system disk that I have permission to distribute includes a MODELA/III file. You can boot this operating system using xtrs's Model 4P emulation and export the file for use in Model III and 4 emulation, or for convenience, click here to download the MODELA/III file directly.

• 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 operating systems (not Model III), 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.

• 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.