TRS-80 Model 100

The TRS-80 Model 100 was an early laptop computer manufactured by Kyocera in Japan and marketed in North America by Radio Shack. Kyocera’s own version, the Kyotronic-85, didn’t set any sales records. But the TRS-80 Model 100 and the line it spawned proved widely successful in the United States.

Arguably the first commercially successful laptop

Powered by an Intel 8085 CPU, everything about the Model 100 was proprietary. But it came with useful software built into ROM, including a word processor, and communications software. This made it easy to use for creating documents on the road and then transferring them to a desktop computer later. Or you could use the built-in modem to send documents back to the office.

One use case for the Model 100 was a newspaper reporter. They could take a Model 100 with them on the road, use the built-in word processor to compose the news story, then use the built-in modem to make a phone call and transmit the story back to the newsroom. The built-in modem and software and the machine’s ability to run for 20 hours on cheap and common AA batteries kept it in use among journalists well into the 1990s, long after it was technically obsolete. I remember being in pre-journalism school in 1993 and 1994, and students a couple of years ahead of me showing me photos from their internships that included images of them using a Model 100.

Overview

The TRS-80 Model 100 hit the market April 26, 1983. Initially it came in two versions, one with 8K of RAM, priced at $1099, and a 24K version for $1399. The 8K version wasn’t very useful and didn’t sell as well. It had a 56-key full-travel keyboard, an expansion bay to expand the memory up to 32K, and a ROM socket to add additional software. One popular option was Microsoft Multiplan, the predecessor to Excel. It weighed three pounds and was 11 5/8 inches wide by 8 inches long and 2 inches thick.

Radio Shack cut prices aggressively, cutting prices to $799 and $999 for the 8K and 24K versions the next year. In 1986, they discontinued the Model 100 and replaced it with the similar Model 102, which had 24K of RAM, was a half inch thinner, and a pound lighter.

Both the Model 100 and Model 102 had a 40 character by 8 line screen, which wasn’t great but when the alternative was writing things out by hand, you’d take it. The CPU’s lack of speed and the slow refresh meant it had trouble keeping up with a fast typist, but you could learn to pause after completing a thought to let the system catch up and to give yourself a chance to read what you’d just written.

Besides running on batteries, it could also run on a 6V AC-DC adapter, center negative.

TRS-80 Model 100 file formats

The Model 100 used a 6.2 filename format, and this can also cause problems if you don’t name the files correctly. The extensions are important. Using the wrong extension causes the data to load into the wrong area of memory and crashes the machine.

• BA – basic files
• DO – documents
• CO – assembly language executables

When trying to run software you found online on a Model 100, be sure to double check the extensions. Software that doesn’t seem to work could just have the wrong extension on it.

The TRS-80 Model 100 and Bill Gates

The other fun thing about the TRS-80 Model 100 is that the built-in software was developed by Microsoft. That’s not especially unusual about a computer from 1980s, but the Model 100 was the last project Bill Gates contributed to as a programmer. So the Model 100 is the last commercial product to contain computer code personally written by Bill Gates.

Today we don’t think of Gates as a software developer, but for years after he wrote his final line of code for Microsoft, his favorite way to try to motivate an employee was to claim he could write something just as good in Basic in 30 minutes.

Snookering a competitor

The Model 100 is also notable for how Tandy executives used it to snooker a competitor. Commodore International was working on a similar machine, code named the Commodore LCD, developed by many of the same engineers behind the well-known Commodore 128. The Tandy executives told their peers at Commodore that LCD was a dead end technology. The Commodore executives canceled their machine, and Tandy released the Model 100 soon after. Commodore fans like me have been asking what kind of executive takes advice from a competitor ever since.

Technical obsolescence and maintaining a cult following

As the decade wore on, the TRS-80 Model 100 had an increasingly difficult time competing with laptop computers that could run MS-DOS. These PC-compatible laptops cost more and were bigger and heavier, had a shorter battery life, and used proprietary battery packs. But their versatility was worth it for many people. That pushed the Model 100 family into a niche like people who simply needed to compose simple documents from remote locations and for whom portability and longer battery life was more important than being able to run Wordperfect and Lotus 1-2-3.

The TRS-80 Model 100 was an unheralded success for Tandy, quietly selling about six million units while the Tandy 1000 line got most of the glory. But with 6 million units sold, the Model 100 sold about as many units as the Apple II line. Admittedly it wasn’t as flashy as an Apple II. And it wasn’t a great general purpose machine. But it was a fantastic niche computer that remained useful even for a few years after you couldn’t buy a new one anymore.

The TRS-80 Model 100’s legacy

Even though it is an evolutionary dead end, the TRS-80 Model 100 proved the concept of what we today think of as a portable computer. Before the Model 100, portable computers folded up like portable sewing machines and were about the size of a portable sewing machine but twice as heavy.

The Model 100 came in a slab-like design with an LCD screen. Its pricier and less popular successor, the Model 200, introduced a clamshell design that would look clunky today, but my kids would recognize it as a laptop computer. Making a super-slim version of a desktop computer wasn’t practical in 1982, but that’s the major difference between the Model 100 series and the laptops I’ve been using professionally for the last 20 years. The size, the design of the keyboard, use of an LCD display, and battery power are all traits that survived into the laptops of this century.

I may find the TRS-80 Model 100 more interesting than most because I’m on armchair historian and have the background in journalism, and if I’d been born just a couple of years earlier, I may very well have used one as a practicing journalist. But even if you don’t have that personal connection, it’s interesting for its resemblance to the computer you probably use at work today, its connection to Bill Gates, and the way Tandy executives outsmarted a rival to get this machine’s biggest potential competitor eliminated before it left the prototype stage.

Fixing a TRS-80 Model 100

These models have a NiCad barrel battery on the motherboard that’s prone to leak, so the first thing you need to do with these laptops is open them up and snip the battery out. If the battery leaked, it damaged traces on the PCB, which is a frequent problem with these machines. The system can run without the backup battery so it’s best to leave it out.

If the keyboard doesn’t work, it’s usually due to damaged traces on the keyboard PCB. A single broken trace can stop multiple keys from working, but soldering a bodge wire onto the broken trace fixes it.

There’s a switch on the underside you can switch to disable the battery, to recovery from a hard system crash. If it’s not in the on position, the system doesn’t boot because it doesn’t have any RAM. This may be the most common cause of a dead Model 100. At least it’s an easy fix.

The capacitors in the switching power supply weren’t the best, so recapping the power supply is a good idea. The capacitors on the mainboard are usually fine unless they’ve visibly leaked.