Posts tagged with “Randy Cook”

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.

The Lobo LX‑80 Expansion Interface

The LX‑80 was an alternative to the Radio Shack Expansion Interface that took a different approach to compatibility than the competition. It was originally announced by Lobo Drives International in Fall of 1979, but problems with the supplied operating system meant that it wasn’t released until closer to 1981. The original price was $799 (without memory), although that price had been reduced to $510 by late 1982.


DoubleDuty is a utility that uses the full 128K of a TRS‑80 Model 4 to allow more than one program to be run at one time. Introduced by Radio Shack in 1984, DoubleDuty was written by Randy Cook, the author of Model I TRSDOS and VTOS.
DoubleDuty works by creating three sections, called partitions, out of the Model 4 memory. Partitions one and two each contain a complete Model 4 TRSDOS system. The third partition is reserved for running TRSDOS library commands.


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 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.