TRS-80 Model 100


So I have a new computer. A Tandy TRS-80 Model 100. So not new, but new to me.

What is it? It’s a laptop computer from 1983, one of the first widely successful models. It’s got a 240×64 resolution display, 40×8 in text mode. Very limited, but also quite useable. Other portables that approached or equalled it in portability had much worse displays- the Epson HX-20 was one of the better ones on this count, and it only had 20×4 text.

On the other end, sure, you could get portables with proper CGA and MDA displays. But these things were enormous- 30-50 pounds was not unheard of. They were a bit easier to pack up and take somewhere else than comparable desktops of the era, but they were not great for mobile use. Many didn’t even have batteries. Luggable is a common and more appropriate term for them, whereas the Model 100 is properly mobile at about 3lbs and 20 hours of use on 4 AA batteries.

Features are great. It’s got a serial port, a parallel port, a cassette interface, a modem port, and a bar code reader jack. The modem port can be used for the built in 300 baud modem(not actually terrible for its era), or to use the Model 100 as an autodialer for a desk phone. The parallel port is good for printers and can be accessed by software for other purposes, and the serial port is good for attaching to disk drives and to use it as a terminal for larger computers. The terminal feature can also be useful for storing files and programs on that larger PC, in addition to running programs on that larger computer.

There’s a text editor, calendar, and basic program as well. Not very high end, but for doing things on the go they would get the job done. The text editor and telcom combination made this machine *very* popular with reporters, who could write up stories in the field and send them in over the modem(with an acoustic coupler available if they can’t get plugged right in to a phone line)

The CPU is a 2.4mhz 80C85, a low power version of Intels 8085, a 5v only variant of the 8080 with some additional microcontroller like features. RAM in mine is 24k, though it was also available for purchase with 8k and can be upgraded to 32. There’s an option ROM port to add additional built in software, and a system bus socket for additional expansion.

Onboard data storage is battery backed RAM. This is the same pool of RAM the system uses to run programs, but it can use the stored copy rather than have to load it again. So you just need to make sure you have enough space free for variables.

Anyways, it’s a fun computer I’ve lusted after since I first saw it in a radio shack ad- and I’m 43, so that’s been a long time. More posts are likely about this thing.

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