Posts in the “Operating Systems” Category

TRSDOS for the Model III

Model III TRSDOS, better known as TRSDOS 1.3, was Radio Shack’s official disk operating system for the TRS‑80 Model III. It was available either bundled with a disk-based Model III, as part of Radio Shack’s floppy disk upgrade, or purchased as a separate product (catalog number 26-0312) for $14.95. Almost everyone who had a disk-based Model III had a copy of Model III TRSDOS.

The Kill Command

The KILL command was probably the most unusually named command in the TRSDOS disk operating systems for TRS‑80 computers. KILL was used to delete a file, for example: KILL FILENAME/EXT.

The KILL command was supported by versions of TRSDOS for the Model I, Model III, and Model II, as well as the BASIC interpreters for all those machines plus the Model 4, Color Computer, the Model 100, Model 102, Model 200, and the Model 2000.

NEWDOS 2.1

NEWDOS 2.1, also known as NEWDOS, NEWDOS/21, and NEWDOS+, was the first alternative disk operating system for the TRS‑80 Model I. Introduced in March 1979 by Apparat, Inc. of Denver, Colorado, NEWDOS jump started the entire third-party TRS‑80 disk operating system market. NEWDOS was considered by many to be an essential program for the Model I; it is quite possible that NEWDOS was more widely used than Model I TRSDOS itself.

MULTIDOS

MULTIDOS was one of the major TRS‑80 operating systems, described in advertisements as “the most compatible, user friendly operating system on the market.” It was written by Vernon Hester, the author of ULTRADOS, and was in some ways a continuation of that operating system. MULTIDOS was the least expensive TRS‑80 operating system and also the one with the most recent update (MULTIDOS 5.1 in 2005).

DOSPLUS

DOSPLUS was one of the most popular of the disk operating systems available for the TRS‑80. Sold by Micro-Systems Software based in Hollywood (later Boca Raton), Florida, there were eventually versions of DOSPLUS for the TRS‑80 Model I, Model III, Model II, and Model 4.

The people behind Micro-Systems Software were Larry Studdard, Mark Lautenschlager, Steve Pagliarulo, and later Todd Tolhurst. According to a 1981 interview in 80-U.S.

VTOS

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.

ULTRADOS

ULTRADOS was the first TRS‑80 operating system written by Vernon Hester. Introduced in September 1980, ULTRADOS was sold by Level IV Products, a software and hardware retailer based in Michigan. The regular price for ULTRADOS was $119.95 but the introductory price of $89.95 lasted for several months. ULTRADOS was for the Model I only; there never was a Model III version.

Originally called Level IV DOS, ULTRADOS began life as a heavily patched version of Model I TRSDOS.

MICRODOS

MICRODOS, later known as OS-80, was the only TRS‑80 disk operating system that made no attempt at TRSDOS compatibility. It was written by James W. Stutsman and released by Percom in 1979. Rather than using a command shell like Model I TRSDOS, MICRODOS used extensions to BASIC. It implemented most of the Disk BASIC commands added by TRSDOS. Also unlike the other operating systems, MICRODOS had no file system. All disk accesses were made using the starting sector and length.

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.