Sean Gallagher





















A while ago, as we at Ars were discussing our first mobile computing experiences, I recalled the first "laptop" computer I was ever issued to use as a journalist: the Radio Shack TRS-80 Model 100. Back on my first field assignment for Government Computer News, I was given the only computing device in the company inventory that could be used to file a story from the field—via acoustic couplers and an MCI Mail account.

Overcome with nostalgia, I put a bid in on a Model 100 on an eBay auction shortly afterward—and then completely forgot about it. Or I forgot about it until about a week and a half ago, when I saw that I had the winning bid. And yesterday, my very own TRS-80 Model 100 arrived in a Priority Mail box (along with the Super Serial card for the Apple II Plus I recently inherited).



The Model 100 was the future of mobile computing when it arrived on the market in 1983. Bill Gates told the National Museum of American History in an interview that the Model 100 was "in a sense my favorite machine." He co-wrote the operating system for the Model 100 with Kyocera's Jey Suzuki. "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," Gates said.

Powered by the 2.4MHz Intel 80C85 and four AA batteries—and squeezing out over 20 hours of battery life!—it has no internal storage other than the RAM (8 or 24 kilobytes, depending on whether you bought the base or deluxe model). The core software for the Model 100 is stored on a ROM chip. It includes a BASIC interpreter, a text editor, a "Telecom" program for remote connections, and an address book application that stores phone numbers for dialing up connections via the built-in 300 baud modem.

The RAM is kept semi-static by power from the AA batteries and an internal backup nickel-cadmium back-up battery when the computer is turned off, but there's a separate power switch for the RAM to turn off when you don't plan to use it for a while (and don't mind losing all your data). If you needed longterm storage (or to free up some of the RAM), files could be written to a cassette tape drive or transferred to another computer—either by modem or serial connection. Radio Shack offered a portable 3.5-inch floppy disk drive as well.

And like the Apple II, the Model 100 and the Model 102 and 200 that followed it—collectively referred to as "Model 'T' computers" by the retro-computing aficionados that still collect and use them—still have a small but active marketplace of hot-rod upgrades to extend their usefulness. Club 100, a Model 100 marketplace and support community founded by Rick Hanson (who passed away in 2011), offers reconditioned systems, souped-up parts, and peripherals. There's an active mailing list and a lot of hardware hacks.

Like with the Apple II Plus I'm working with, my Model 100 is going to require some care and feeding to achieve connectivity. I need to track down a phone cable compatible with the archaic modem socket (or maybe some acoustic couplers), but I'm also considering tethering it serially to a Raspberry Pi—which, ironically, costs more than I paid for my Model 100 and has significantly more computing power. When it first hit the market, the 24 Kilobyte Model 100 cost $1,399 (in 1983 dollars); I acquired mine, minus its peripherals, for $35.

Of course, there's also this thing called the NADSbox that I may need to acquire, and various other parts. So to get the Model 100 online again may end up pushing the final price of my purchase a bit closer to its 1983 price tag. But it's all in the name of historical science, right?

Your suggestions on what to attempt with this particular piece of our computing heritage are welcome, as always. Additionally, someone's already offered me an Amiga 500 to do the flashback thing with; if there are any other retro/vintage systems you'd like to see resuscitated (within reason), let me know. I've already decided there's no room in the basement for a PDP-10.

Listing image by Sean Gallagher