The Four Decade Later Upgrade
Mar. 23rd, 2025 06:52 pm![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
krpalmerWith what keeps being said about the TRS-80 Model 100 more than four decades after its introduction, there are moments I imagine being accused of insufficient appreciation of that pioneering portable. One of those computers has been in my family for more or less forty years now. In recent years, though, when I’ve switched it on that was as much to see that it could still be switched on as anything.
When the rhetoric about the Model 100 includes “it powers up in instants, enters its text editor almost as fast, runs for hours on easily replaceable AA batteries, and has the kind of full-travel keyboard you have to pay a lot for these days,” I can suppose that presents the computer as a writing device. What I have to admit, though, is that as far back as the early 1990s (when I was still linking it to a Color Computer to transfer text off it), the eight lines of forty characters each on its display could get to feeling like a cramped window on what I’d written. (My tendency to pile up complicated sentences probably doesn’t help there. So far as my ability to still handwrite legibly goes, not that long ago I realised the composition books I use have space for less than “forty characters per line,” but I can look back to a good number of lines on a finished page.) So far as using it as a general-purpose computer goes, a good number of years later I did work out how to launch the client programs that can serve files to a Model 100 from more modern devices, only to wind up with the impression there wasn’t quite the same library of interesting software for it as for desktops of its day.
A number of years after that, however, I picked up on an add-on gadget for the Model 100 that did get my attention. There had been “extra memory banks” hooked up to an expansion option accessible from the computer’s underside since the 1980s. The decades-later option that got my attention, while requiring the computer’s batteries to stay charged to hold data, promised to let it run CP/M, the early operating system associated with somewhat more formidable machines. Having dabbled with CP/M via emulation, the thought of “running it on real hardware” had a peculiar appeal to it. At last, I contacted the person selling the “REXCPM.” He explained he’d have to build some more before he could sell them. After a bit of a wait, he contacted me again and said I could now make my order.
One thing I admitted then was that I didn’t know much more longer my Model 100 would work. There had been recommendations for years to desolder and replace a battery tied to the motherboard before it corroded and wiped out everything around it, but the “learn to solder” kit I’d once bought hadn’t built a lot of confidence. The person suggested that if I could get the motherboard out of my computer and mail it to him, he’d replace the battery and some potentially worn-out capacitors as well.
That much I thought I could do. After finding the Model 100 service manual online, I got the case screws loose with only some difficulty, managed to unlatch the halves of the case, and disconnected the cables connecting the motherboard to the LCD and keyboard before getting the board unscrewed from its half of the case. I was still uncertain about what shape the board had emerged in, though, and did recall certain projects involving connecting the Model 100’s keyboard to a Raspberry Pi.
Then, reports were sent to me the repairs had been successful and the REXCPM had been installed. Once the circuit board arrived in the mail, I managed to reverse the steps that had got it out of the case. With everything reassembled, I clicked the power switch back on, and the screen stayed blank. After some sinking feelings, I remembered the dial that adjusted the LCD “viewing angle.” Turning it brought the screen back.
I’ve managed to get CP/M started on the Model 100. It happened to have been preloaded with Zork I, but I was able to get another adventure game running on it using the old Infocom interpreter. In patching the interpreter to access the game file, I was also able to patch it to fit its text on the computer’s screen. While it takes starting up the one old computer I have dual-booting into the years-unpatched Windows 7, I’m also able to run a terminal that lets the Model 100 drive a twenty-four-line-by-eighty-column display, and typed up this post using it. For once I thought I could “see enough,” but I did get the impression the text editor can start to get poky when revising in the middle of a document.
When the rhetoric about the Model 100 includes “it powers up in instants, enters its text editor almost as fast, runs for hours on easily replaceable AA batteries, and has the kind of full-travel keyboard you have to pay a lot for these days,” I can suppose that presents the computer as a writing device. What I have to admit, though, is that as far back as the early 1990s (when I was still linking it to a Color Computer to transfer text off it), the eight lines of forty characters each on its display could get to feeling like a cramped window on what I’d written. (My tendency to pile up complicated sentences probably doesn’t help there. So far as my ability to still handwrite legibly goes, not that long ago I realised the composition books I use have space for less than “forty characters per line,” but I can look back to a good number of lines on a finished page.) So far as using it as a general-purpose computer goes, a good number of years later I did work out how to launch the client programs that can serve files to a Model 100 from more modern devices, only to wind up with the impression there wasn’t quite the same library of interesting software for it as for desktops of its day.
A number of years after that, however, I picked up on an add-on gadget for the Model 100 that did get my attention. There had been “extra memory banks” hooked up to an expansion option accessible from the computer’s underside since the 1980s. The decades-later option that got my attention, while requiring the computer’s batteries to stay charged to hold data, promised to let it run CP/M, the early operating system associated with somewhat more formidable machines. Having dabbled with CP/M via emulation, the thought of “running it on real hardware” had a peculiar appeal to it. At last, I contacted the person selling the “REXCPM.” He explained he’d have to build some more before he could sell them. After a bit of a wait, he contacted me again and said I could now make my order.
One thing I admitted then was that I didn’t know much more longer my Model 100 would work. There had been recommendations for years to desolder and replace a battery tied to the motherboard before it corroded and wiped out everything around it, but the “learn to solder” kit I’d once bought hadn’t built a lot of confidence. The person suggested that if I could get the motherboard out of my computer and mail it to him, he’d replace the battery and some potentially worn-out capacitors as well.
That much I thought I could do. After finding the Model 100 service manual online, I got the case screws loose with only some difficulty, managed to unlatch the halves of the case, and disconnected the cables connecting the motherboard to the LCD and keyboard before getting the board unscrewed from its half of the case. I was still uncertain about what shape the board had emerged in, though, and did recall certain projects involving connecting the Model 100’s keyboard to a Raspberry Pi.
Then, reports were sent to me the repairs had been successful and the REXCPM had been installed. Once the circuit board arrived in the mail, I managed to reverse the steps that had got it out of the case. With everything reassembled, I clicked the power switch back on, and the screen stayed blank. After some sinking feelings, I remembered the dial that adjusted the LCD “viewing angle.” Turning it brought the screen back.
I’ve managed to get CP/M started on the Model 100. It happened to have been preloaded with Zork I, but I was able to get another adventure game running on it using the old Infocom interpreter. In patching the interpreter to access the game file, I was also able to patch it to fit its text on the computer’s screen. While it takes starting up the one old computer I have dual-booting into the years-unpatched Windows 7, I’m also able to run a terminal that lets the Model 100 drive a twenty-four-line-by-eighty-column display, and typed up this post using it. For once I thought I could “see enough,” but I did get the impression the text editor can start to get poky when revising in the middle of a document.