When the TRS‑80 Model I was introduced on August 3, 1977, it came with Level I BASIC, a 4K BASIC interpreter, in ROM. Level I BASIC was created by Steve Leininger, the designer of the TRS‑80, who based it on the public domain “Palo Alto Tiny BASIC” that Dr. Li-Chen Wang wrote in 1976.

But Radio Shack’s plan was always to upgrade to a more advanced Model I BASIC later. The very first TRS‑80 brochure said that “planned expansion includes an extended Radio Shack Level II BASIC.” It was mentioned again in the first issue of the TRS‑80 Microcomputer News (then known as the Radio Shack Microcomputer Newsletter) in 1977:

A Level II BASIC is now being developed. This will be a 12K BASIC with every feature you ever imagined — PEEK and POKE, PRINT USING, transcendental functions, advanced string handling, etc. It should be available on ROM soon.

The Aerocomp DDC

The Aerocomp DDC was a popular double-density add-on for the TRS‑80 Model I. It was introduced in 1981 by Aerocomp Inc. of Dallas, Texas, a company founded by John Lancione. Aerocomp was one of the longest lasting TRS‑80 companies and the Aerocomp DDC was sold for almost a decade.

When it was introduced, the Aerocomp DDC cost $149.95. This was $20 cheaper than its primary competitor, the Percom Doubler II. Aerocomp also sold the Aerocomp DDC bundled with a choice of operating systems: DOSPLUS 3.3 for $189.95 and with LDOS for $239.95.

The Percom Doubler was the original Model I doubler and the Aerocomp DDC was designed to be software compatible with it. The Aerocomp DDC (like the Percom Doubler) used double-density encoding to increase disk capacity on a 40-track single-sided disk from 100K to 180K

The Freedom Option

The Freedom Option was a CP/M add-on for the TRS‑80 Model I, Model III, and compatibles. It was introduced in early 1980 by Field Engineering Consultants (better known as FEC) of Woburn, Massachusetts.

Originally, FEC sold two Freedom boards, both for a 48K Model I with disk drives:

  • The Freedom Option allowed CP/M (or the included T8/OS) to run by disabling the Model I ROM. It cost $245.00.
  • The Memory Expansion Option had the same features as the Freedom Option, but also added an extra 16K of RAM. This provided a full 64K of RAM for the Model I, meaning that 57K was available for programs when running T8/OS. It cost $295.00.

Both the Freedom Option and the Memory Expansion Options were fairly small boards that installed inside the Model I case. As one advertisement stated they were “easy to install plug-in boards; no wires or traces to cut; no soldering.”

Radio Shack Games Packs

Most people considered the Big Five Software games to be the finest games ever written for the TRS‑80 Model I and III. They were sold directly through Big Five and were resold by many other companies.

Radio Shack also sold Big Five games in two collections compiled by Cogito Software. Games Pack Two and Games Pack Three first appeared in the 1984 Radio Shack catalog and contained four Big Five games: Defense Command, Stellar Escort, Cosmic Fighter and Meteor Mission 2. As the packaging stated: “You can look forward to hours of fun for the family, friends, or even the gang at the office.”

Both collections were sold on cassette and self-booting disk. Only minor modifications were made to the games, the biggest being that all copyright messages were changed to “Licensed to Tandy Corporation.”


Word processing was one of the most important applications for early microcomputers. WordStar, introduced in 1979 by MicroPro International, became the best selling word processor soon after it was introduced. According to the market research firm InfoCorp, WordStar was the most popular word processor in 1984 with 24% of the worldwide market.

MicroPro sold versions of WordStar for CP/M (including Apple II CP/M) and MS-DOS. Many people bought a CP/M add-on for the TRS‑80, such as the Omikron Mapper, just to run WordStar.

WordStar was written by John Robbins Barnaby (usually referred to as Rob Barnaby) with assistance from Jim Fox. MicroPro began shipping the first version of WordStar in mid-1979.

Here is the announcement from a MicroPro advertisement introducing WordStar (then billed as WORD-STAR) in the April 1979 issue of BYTE:

Pion’s Interstellar Drive

The Interstellar Drive, also known as Pion’s Interstellar Drive, was a solid state disk drive emulator that was sold by Pion, Inc. of Arlington (later Watertown), Massachusetts. It was introduced in 1982 for a base price of $1,095.00 for the 256K version.

The Interstellar Drive was an external 9″ by 8 1/2″ by 4″ unit with its own power supply. It was compatible with the TRS‑80 Model III and Model 4 and included drivers for the TRSDOS and LDOS disk operating systems. By using different host interfaces, the Interstellar Drive was compatible with a number of computers, including the Apple II and the IBM PC.

Much like a modern solid state drive, the Interstellar Drive had no moving parts. It provided non-volatile data storage at speeds far greater than a hard drive (then commonly known as a Winchester drive) or a floppy drive. Advertisements described the Interstellar Drive as providing “five to fifty times faster performance than floppy disks and Winchester drives.”

The FPS-3

The FPS-3 was an unusual hardware add-on for the TRS‑80 Model III and Model 4 that gave users the ability to make backup copies of their copy protected TRS‑80 programs. It was created by Steve Sawyer and sold for $50.00 through his company J.E.S. Graphics of Tulsa, Oklahoma.

Most products that could defeat TRS‑80 copy protection, such as Super Utility or Trackcess, were software that used the TRS‑80 hardware to make exact copies of protected disks or tapes. This didn’t always work depending on the type of protection used. The most notable example was Super Utility, which couldn’t be used to make copies of itself!

Rather than use this approach, the FPS-3 was hardware that made copies of the data that a protected program loaded from disk or tape. It could create an exact snapshot of a program immediately after it had loaded into memory. As long as the protected program loaded completely from disk or tape with no overlays (as most did), the FPS-3 could be used to create an unprotected copy.

The TRS‑80 Applications Software Sourcebook

The TRS‑80 Applications Software Sourcebook, also known as the Applications Sourcebook, was a book containing short descriptions and information about third-party application software for the TRS‑80. It was published by Radio Shack with at least eight volumes from 1980 to 1987.

Any publisher could buy a listing in the TRS‑80 Applications Software Sourcebook. A listing cost $10.00 and included the name of the program, the price, a short description, TRS‑80 compatibility information, and ordering details. A listing could only mention one program and there were no discounts for multiple listings.

Radio Shack first announced the TRS‑80 Applications Software Sourcebook in the March/April 1980 issue of the TRS‑80 Microcomputer News:

The TRS‑80 Micro Computer System Desk

The TRS‑80 Micro Computer System Desk (catalog number 26-1301), also known as the TRS‑80 System Desk, was Radio Shack’s recommended desk for the TRS‑80 Model I. It was introduced in 1978 for a price of $199.00.

The TRS‑80 System Desk was designed to hold a Model I, monitor, Radio Shack Expansion Interface, up to four floppy drives, and a TRS‑80 Quick Printer, with all wiring hidden inside the desk. As one advertisement stated, the TRS‑80 System Desk “concentrates your expanded TRS‑80 system into one convenient area.”

The Hurricane Labs Compactor

The Hurricane Labs Compactor was part of a series of products that modified the TRS‑80 Model III to allow it to run CP/M programs. Hurricane Laboratories, better known as Hurricane Labs, was founded by Ronald L. Jones, a member of the Homebrew Computer Club who had a great deal of experience with CP/M.

There were three Compactor products for the TRS‑80 from Hurricane Labs, all designed by Ron Jones:

  • The Compactor I, introduced in late 1981, sold for $450.00, including a customized version of CP/M. It converted the Model III into a 48K CP/M computer.
  • The Compactor II was introduced in late 1982. It added the same features as the Compactor I, but also doubled the Model III speed using a 4 MHz Z80A processor. The Compactor II included an extra 64K of memory to create a 112K CP/M computer. It also provided a real-time clock with battery backup. I have never seen a reliable price for the Compactor II.
  • The Compactor IV wasn’t a CP/M board, but an 80 by 24 video board. It cost $475.00 and installed in place of the Model III RS-232 board. The Compactor IV emulated a Lear Siegler ADM-3A terminal, with reverse video, underline, and blinking. It also included a serial port to replace the one normally provided by the stock RS-232 board.