TRS-80 Model 100: Back From The Brink


The TRS-80 Model 100 is a computer you owe a lot to, even if you don’t recognize it. Released in 1983 by Tandy (now known as RadioShack) for $1099 USD, the Model 100 was one of the world’s first “notebook” computers. At the time its design was radical, as computers had always been large objects tethered to bulky CRT monitors; the Model 100 helped introduce concepts we all take for granted now, such as all-in-one construction, integrated LCD display, and the ability to run on battery power. Selling over 6 million units, the Model 100 proved that a highly portable computer could be successful, and we’re still seeing the effects of that today.

But after nearly 30 years, the Model 100 is really showing its age. The hardware specifications are below what we would expect even from a microcontroller like the Arduino, to say nothing of a modern computer or smartphone. Does this old tank have any life left in it, or is it best suited for the museum? Could you connect it to a modern system and get new software for it, even if you wanted to?

Hardware Specs

TRS-80 Model 100
Processor Intel 80C85 @ 2.4 MHz
RAM 8KB, Upgradable to 32 KB
Storage 32 KB ROM, Optional 3.5 Inch Floppy Drive
Screen 8 line, 40 character LCD @ 240×64
Power Four AA Batteries
Networking Built-in 300 baud modem, serial port
Dimensions 300x215x50 mm, approx weight 1.4 kg (3.1 lb)


With hardware specs like that, you might wonder why anyone would bother getting one of these things up and running again. Interestingly enough, some of the Model 100’s key features are still in demand for certain applications. The Model 100 is able to run an incredible 20 hours on a set of 4 AA batteries, and its low energy consumption make it well suited for conversion to solar or other off-grid energy sources. Combined with the fact the machine doesn’t have a single moving internal component and has a built in analog modem and serial port, the Model 100 is very well suited to data collection and reporting in remote locations or areas where more delicate hardware may have trouble coping.

For the “nuts and bolts” types out there, there is no better teardown and examination of the Model 100 than what David L. Jones has done for his EEVblog:

Interesting Facts

Its renowned reliability aside, there are a number of interesting bits of trivia involving the Model 100 which has helped cement its position in computing history. Such as the fact that the Model 100 is the last product for which Bill Gates personally wrote a sizable part of the code.

Part of my nostalgia about this machine is this was the last machine where I wrote a very high percentage of the code in the product. I did all the design and debugging along with Jey.

Bill Gates

In a twisted bit of irony, the Model 100 also has the distinction of being one of the only devices that was actually affected by the “Y2K Bug“; the theorized glitch which would cause computers to become confused as the year switched over from 1999 to 2000 due to the fact that many old pieces of software were only designed to take into account the last two digits of the year, and assumed the first two were always going to be “19”. As predicted, the Model 100 believes this to be the year 1912. Thanks, Bill.

TRS-80 Community

Whether you had one from the 80’s or bought one on eBay recently, you’re going to want to get some software for it. Luckily there is a very dedicated TRS-80 community out there that is still pumping out software for the various TRS-80 models. For the most up to date information and software, check out the indispensible Club100:

There you can find software for your Model 100, documentation on the computer and its accessories, information on how to connect the Model 100 to other devices, and basically anything else you could possibly want to know about a 30 year old computer.

You may also want to check out the WEB 8201 site, which is dedicated to the NEC PC-8201A, but also serves up software downloads for its close relatives including the Model 100.

Before you dig into the hardware side of things, you may also want to take a look at Virtual T, an open source Model 100 emulator for Linux, Windows, and Mac OS. Using Virtual T, you can test out (or write) software before putting it on the actual Model 100 hardware. This gives you the opportunity to test drive a piece of software without taking the time to install it on the real device.

Installing Software

No matter how you ended up with a Model 100 and the desire to do something with it in 2012, one thing is certain, you won’t be doing a whole lot with it until you can install some new software. There are actually a lot of different ways you can go about this, using different protocols, commands, and hardware. The methods used even differ depending on what you want to transfer, as you can transfer plain text files faster (and in different ways) than you can BASIC programs.

For the sake of this guide we are going to assume that you are only interested in transferring BASIC programs from your Linux computer to your Model 100. We’re going to use the method which requires the fewest steps and seems to work the most reliably, though unfortunately, this is also the slowest method. Of course, you probably shouldn’t expect much in the way of speed on a 2.5 MHz computer in the first place.

About Tom Nardi

Tom is a Network Engineer with focus on GNU/Linux and open source software. He is a frequent submitter to "2600", and maintains a personal site of his projects and areas of research at: .
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  • Lucas.

    Hi! Your posting is great, but while I was watching the video, two annoying sound ads begun to play.Could you remove this? Thanks a lot! :)

    • Tom Nardi

      Sorry about that, we’ve been having issues with the ad provider recently. The problem should be fixed in the very near future.

      • gfsdg

        ad blocker! although it does not stop the IRRITATING “please like me on facebook” thing.

  • allenbeme

    Y2K bug? My Model 4p had to be patched to show correct dates in the 1990’s. I had to use Pickles and Trout’s CPM.

  • Fallingwater

    I’ve been looking for a TRS80M100 for a while now. No luck so far. If I find one I’ll probably have a lot of use for this guide. Thanks for putting it up.

    That said:

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  • enzo aggazio

    In Italy, it was brand by Olivetti by name M10 ..

  • Howard

    I was lucky enough to know Rick Hanson, although we only talked on the telephone a couple of times, we did the majority of our correspondence via email. I owned a TRS-80 Model 100 back in the mid 1980’s, and even took it out on a Mediterranean cruise (I was in the Navy at the time) in 1986-1987. I made the (foolish) mistake of giving it away in the early 1990’s, only to regret that decision later. Rick was the person I reached out to, when I got my second Model 100, several years ago. I still have that Model 100, along with a second one, a Tandy Model 102, and a Tandy 200. These may not be the fastest computers, or have the most memory, but they are hearty, and last for a long time.

  • jhoger

    Also check out my site, . There’s a wiki with m100 programming info and com software that will let you transfer data at the limit of the machine. 76800bps is achievable when hardware flow control is implemented. Also HTERM will let you deal with UTF8 chars from a Linux system.

    Make sure to sign up for the mailing list and join the m100 user community to get support.

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  • Charles H Martin

    OMG I forgot about the cassette port. It was awesome!

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  • smithvoice

    Life is a lot easier with a NADSBox, 64GB on SDHC plugged right into the Model T.. I have actually found that my m200 (the clamshell version of the 100) is fun and truly useful again with REX and NADSbox installed. Check Club100 for details. Truly great to type real BASIC and even ml on these things… I was so happy being offline and focused again (amazing how being wired has changed us… go without google being a click away and you quickly get more done!) that I just got a 100 off ebay to get the smaller screen and force myself to think out every byte of code. Been a cutting edge developer for years with the best new boxes always in my bag… but this amazing antique is simply blowing me away.

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