The TRS-80 Pocket Computer

written by Matthew Reed

The TRS-80 Pocket Computer (catalog number 26-3501) was the first in Radio Shack’s line of pocket computers. It cost $249.00 when it was introduced on July 31, 1980, the same day as the TRS-80 Model III and the TRS-80 Color Computer. The Pocket Computer was renamed the PC-1 in 1982 after the PC-2 was introduced.

Unlike their other computers (the Model I, Model II, Model III, and Color Computer), the Pocket Computer wasn’t a Radio Shack design. It was actually a rebadged Sharp PC-12111, which had been introduced in Japan the same year. (At the time, the PC-1211 wasn’t available in the United States.)

The TRS-80 Pocket Computer

The Pocket Computer from a 1981 Radio Shack catalog

The Pocket Computer weighed only six ounces and measured 6 7/8" by 2 3/4" by 11/16", which meant that it really could fit in a pocket.2 It used two 4-bit processors3 and provided 11K of ROM (for BASIC) and 1.9K of RAM (for user programs). The display was a 24-character LCD that could show one line with uppercase characters only. Unlike a calculator, the Pocket Computer had a 57-key QWERTY keyboard, albeit somewhat reduced in size. The Pocket Computer was powered by four PX675 mercury4 batteries which provided 300 hours of use.

The biggest selling point of the Pocket Computer was the built-in BASIC. Program capacity was defined in steps, and the PC-1 offered 1,424 steps in its 1.9K of RAM. (Because of the small size of tokenized BASIC programs, this was actually a lot more capacity than it sounds.) Here is a description from a 1981 Radio Shack catalog:

You can program the Pocket Computer to do almost any of the smaller jobs that the TRS-80 microcomputer can do, except those requiring graphics capabilities. Program it to file a stock portfolio, or to calculate business, engineering, or scientific problems. Programs can be saved on cassettes (with the optional cassette interface and recorder), or left in memory for as long as needed.

Pocket Computer plus Printer/Cassette Interface

The Pocket Computer and Printer/Cassette Interface from a 1982 Radio Shack catalog


For saving BASIC programs, Radio Shack sold the Pocket Computer Cassette Interface (catalog number 26-3503) for $49.00 (later $29.95). It used 3 AA batteries and measured only 3 1/2" by 8 1/4" by 7/8". Radio Shack’s $79.95 Minisette-9 (catalog number 14-0812) was recommended for use with the Cassette Interface, but it would work with most cassette recorders

In 1982, Radio Shack introduced the Printer/Cassette Interface (catalog number 26-3505) for $149.00 (later $127.95). The Printer/Cassette interface worked like the earlier Cassette Interface, but also included a printer that printed on 1 3/4" wide paper. It came with built-in rechargeable batteries which could print about 8,000 lines on one charge. Extra paper (catalog number 26-3506) for the printer cost $1.75 for six rolls.


Some third-party companies sold software for the Pocket Computer, but Radio Shack was the primary source of software and they sold a surprising number of Pocket Computer software packages. These were mostly professional programs, such as Real Estate (catalog number 26-3510) for $24.95, Math Drill (catalog number 26-3514) for $14.95, Engineering Math 1 (catalog number 26-3525) for $14.95, and Surveying (catalog number 26-3512) for $29.95.

Radio Shack also sold a few game packages, including Games I (catalog number 26-3515) and Games II (catalog number 26-3523) for $14.95 each. These included games such as NIM, Space Ship Landing, Treasure Hunt, Blackjack, Baccarat, and Craps. (Remember that all these games had to work within a 24-character display.)

The PC-2 and the PC-3

In 1982, Radio Shack introduced a new Pocket Computer named the PC-2 (catalog number 26-3601). The original Pocket Computer, which was still being sold, was renamed the PC-1. Its price was dropped to $159.95 and then $149.95 in 1983. The PC-2 was a rebadged Sharp PC-1500 and was far more powerful than the original Pocket Computer, but wasn’t compatible with any of its software or hardware.

Pocket computer sales in the United States reached $150 million in 19835. That same year, Radio Shack introduced two new Pocket Computers: the PC-4 and the PC-3. The PC-4 was made by Casio (the Casio PB-100) but the PC-3 was made by Sharp (the Sharp PC-1251) and was software compatible with the original Pocket Computer. Radio Shack discontinued the original Pocket Computer (the PC-1) after the introduction of the PC-3.

Today, with ubiquitous tablets and smartphones, it’s hard to understand just how much of a technological innovation the Pocket Computer was. It is partly illustrated by this story from the January 11, 1982 issue of InfoWorld involving the science fiction author Isaac Asimov (who at the time was a Radio Shack spokesman):

At a recent photo session in New York city, someone from Radio Shack looked at the Pocket Computer that Asimov was holding and asked him, “How close is that to the computer you described in the first volume of the Foundation trilogy?” (The Foundation trilogy is Asimov’s seminal science-fiction masterpiece written in 1951.)

Asimov looked at the computer for several seconds, nodded his head and said, “This is it.”

  1. In fact, all eight of Radio Shack’s Pocket Computer models (PC-1 to PC-8) were made by either Sharp or Casio. The PC-1 was the Sharp PC-1211, the PC-2 was the Sharp PC-1500, the PC-3 was the Sharp PC-1251, and the PC-8 was the Sharp PC-1246. The PC-4 was the Casio PB-100, the PC-5 was the Casio FX-780P, the PC-6 was the Casio FX-790, and the PC-7 was the Casio FX-5200P. ↩︎

  2. David Busch parodied this aspect of the Pocket Computer in his News from Kitchen Table Software column in 80 Micro. In his fictional version, Kitchen Table Industries, Inc. introduced the TLS-8E Pockets Computer, so-called because it was too large to fit in one pocket. ↩︎

  3. This wasn’t true parallel processing because the two processors didn’t run at the same time. ↩︎

  4. PX675 batteries, like all mercury batteries, are almost impossible to buy today. The sale of mercury batteries was effectively banned in the United States in 1996. Zinc-air and silver oxide batteries, although not exactly equivalent in capacity or shelf life, are common replacements. ↩︎

  5. This figure was for the entire pocket computer market, which included products from Hewlett-Packard, Sharp, and Panasonic, not just Radio Shack. ↩︎

Categories: Computers