Posts tagged with “TRSDOS”

What was the inspiration for TRSDOS?

Just about all computer software has taken inspiration from other software that has preceded it, and operating systems are no exception. For example, it is well known that MS-DOS was based on CP/M, with some ideas borrowed from TOPS-20. Windows has strong structural similarities to VMS (both were designed by Dave Cutler). CP/M was itself inspired by TOPS-10. UNIX was inspired by Multics. And the list goes on.


VTOS (which stood for “Virtual Technology’s Operating System”) was the second TRS‑80 Model I operating system created by Randy Cook, the author of Model I TRSDOS. VTOS was released in 1979 and sold through Randy Cook’s company, Virtual Technology Inc. The original price was $49.95 for VTOS version 3.0. That was increased to $99.95 for version 4.0, or $125.00 for VTOS plus Operator’s Guide and Master Reference manual. There doesn’t appear to have been a Model III version of VTOS.

TRSDOS 2.3 Decoded and Other Mysteries

TRSDOS 2.3 Decoded and Other Mysteries was written by James Lee Farvour and published by IJG in 1982. It was volume six in the TRS‑80 Information Series.

In a way, this book was a companion to James Lee Farvour’s earlier Microsoft Basic Decoded and Other Mysteries. That book analyzed TRS‑80 Model I BASIC in great detail, describing how each part of the language worked. At the end of the book, it included the commented portion of a disassembly of the BASIC.

Model I TRSDOS Versions

TRSDOS 2.0 was the first version of Model I TRSDOS to be released to the public. All earlier versions had been used for testing within Radio Shack only. It came with a preliminary instruction manual, with a final manual promised for the near future. Not many people used TRSDOS 2.0 because it was replaced by TRSDOS 2.1 after only a short time.

Model I TRSDOS Disk BASIC Commands

Model I TRSDOS Disk BASIC contained a number of extra commands and enhancements to Level II BASIC, not all related to disk. The commands were documented in the TRSDOS 2.3 Reference Manual. All other TRS‑80 operating systems with a Disk BASIC supported these commands, although often CMD and NAME used different syntax.

Model I TRSDOS Commands

The Model I TRSDOS command shell supported a number of internal commands, as documented by the TRSDOS 2.3 Reference Manual. Most of the commands were also supported by other TRS‑80 operating systems, although they usually added extra features beyond the TRSDOS versions.

TRSDOS for the Model I

TRSDOS, referred to as DOS in some early references, was Radio Shack’s official disk operating system for the Model I. The name stood for Tandy Radio Shack Disk Operating System. It was bundled with Radio Shack’s floppy disk upgrade, but it could also be purchased separately.