Matthew Reed's TRS-80.org


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.

Was the Model I ever sold as a kit?

Some have claimed that Radio Shack offered the Model I as a kit before selling it as a fully-assembled computer. That is not true. From the very beginning, the TRS-80 was sold only fully assembled and there was never a TRS-80 kit option in any Radio Shack catalog.

Was the official name Model 3 or Model III?

Model III was the official name, although 3 and III were and are used interchangeably by many people.

The Model I, II, and III were the only three TRS-80 computers to be identified with Roman numerals in the Radio Shack catalogs. Although some pre-release information identified the “Model IV,” the Radio Shack catalogs always used “Model 4.” All future computer models used ordinary numbers.

Was there a Level I Model III?

Although rare, the Level I Model III did exist. The 1981 Radio Shack catalog which introduced the Model III listed three versions:

  • 26-1061, 4K Level I BASIC, cassette only, $699.00
  • 26-1062, 16K Model III BASIC, cassette only, $999.00
  • 26-1063, 32K Model III BASIC, two floppy drives, $2,495.00

Was the TRS-80 affectionately known as the Trash-80?

It seems that whenever any article today mentions the TRS-80, it always includes a statement that the TRS-80 was “affectionately known as the Trash-80.” Although this idea is often repeated, it is simply not true.

“Trash-80” was a common corruption of the TRS-80 name. It was intended to suggest that the TRS-80 hardware and software were of poor quality and little better than trash.

Many have embraced the name in recent years and that has caused “Trash-80” to lose much of the original negative connotation. But that is a recent development and was definitely not the case back when Radio Shack was still selling the TRS-80.

Frogger

Although there were many Frogger adaptations for the TRS-80, this Cornsoft Group version was licensed by Sega and was the “official” Frogger. The premise of Frogger is simple. The goal is to guide as many frogs as possible back to their homes, crossing a busy road and dangerous river in the process.

The TRS-80 version of Frogger offers the choice of five difficulty levels and an option to play background music. The famous theme music, taken from the Japanese children’s song “Inu No Omawarisan”, is the same as used in the original arcade version. Most TRS-80 games played music during title screens and sound effects during the game. Frogger was one of the few to also play background music during the game, not an easy feat on a computer with no sound controller.

Outhouse

Outhouse is probably the TRS-80 game with the most bizarre premise. It was written by J. Weaver Jr. (Factory Programming) and distributed by Soft Sector Marketing. Outhouse was later rewritten for the Color Computer by the same author, but sold through Computer Shack.

Priming the Pump: How TRS-80 Enthusiasts Helped Spark the PC Revolution

Lately, there seems to be an increasing interest in the history of early microcomputers. But for whatever reason, Radio Shack and the TRS-80 are rarely mentioned in histories of microcomputing. When the TRS-80 is mentioned, the details are often incomplete or completely wrong. I don’t know what has caused this collective amnesia, but the TRS-80 deserves to have its important contributions recognized.

The Programmer's Guide To LDOS/TRSDOS Version 6

The Programmer’s Guide is my favorite TRS-80 programming book, and in my opinion, the most useful. The chapters include:

  • an overview of the operating system
  • device input/output, with information about filters and drivers
  • disk drive input/output, with information about writing a disk driver
  • DOS directory structure
  • disk file access and control
  • interfacing with supervisory calls (SVCs), including detailed information about parameters
  • other useful miscellaneous tables and topics

Programming the Z80

Even though Programming the Z80 was not written for the TRS-80, it was one of the more popular TRS-80 programming books. I suspect that this book and TRS-80 Assembly Language Programming by William Barden introduced more TRS-80 programmers to assembly language than any others.