Tandy TRS-80 Model 100 Teardown

This was mt first computer! I remember buying it the moment I laid eyes on it. After walking out of the store with my co-worker (we were corporate pilots) I started having buyer's remorse. Mainly, I spent the rest of the day lamenting "my wife is gonna kill me!"

My partner thought it was pretty funny. But I got the last laugh. My wife trusted me to be responsible for my own decisions.

If you think about it, that kind of "non" reaction makes more sense (evolutionarily?) than berating and brow-beating the spendthrift husband:

If he has a good head on his shoulders he'll strive not to abuse that trust.

If he's a deadbeat he'll abuse that trust swiftly, and you'll waste no time getting to the point of filing divorce papers.

We've been married 30 years come this August.

Anyway, funny how this thread shows up the day after I mention the model 100/101/102 in a thread here about quality keyboards. The 101 I had was the perfect keyboard for me.

For a few years I tried to figure out how to use the 101 as the keyboard for the newer laptops I bought. ...I've always been primarily a laptop-type, I wonder why...?

I mentioned in that other thread that I eventually gave it to a friend who pressed it into service as a switch for a set of phones. As of about 6 years ago it was still clicking away.

Not long after I gave it to him, this fellow showed me how easy (easy for him to say) it was to use it as an external keyboard. But without some sort of interpretation on the receiving end he said there would be a lot of weird characters resulting from a vast different in standards... whatever. This guy is the geek supreme. Runs the tech for a TV station. First Linux I ever saw running, he got me started on FOSS.

Memories. Of all the computers I have owned I wish I still had that 101 more than any other. I have the second one after the 101 still, but it quit working around 2005. Model 2810HD IIRC. The "HD" was for "Hard Drive." The felt they should mention in the name that this computer had one. The 10 meant a whopping 10 MB on the "HD."

That was an 80286 machine. I think I probably got the most production, serious work for the business, out of that unit. I wrote a formula for calculating what the cost of an airline ticket would be to any destination, whether an airline went there or not. This was based on the seat tax.

I was able to reverse engineer what that cost would be, and compare it to the cost per passenger on our aircraft, on a flight by flight basis. At the end of the year I could sho each of the 4 companies involved what their airline costs would have been, and what they actually spent.

3 of the 4 saved a ton of real money by operating their own aircraft, and this was before hotels, lengthy car rentals and intangibles like employees having to be away from home often.

The 4th didn't care. The plane was somewhat useful, more a luxury (impressed a lot of potential customers) and he could afford it.

All with a 286. I justified my job with it! Through a couple pretty lean years.

Talk about irony (and honesty) I used a subsequent P-II/win98 lappy to push the pencil, concluding we should disolve the flight department and put me on the street. The unfortunate consequence of government mandated major engine overhaul. Forget their actual condition, at XXX hours you rebuild, no arguments.

I recommended this to the board, and they went with it. It bought me a little respect in this town...

Staring out over snowbound New York from my digital loftspace, past the array of quadcore-driven, fiber-fed widescreen monitors, my Android phone vibing at my hip, picture of post-millennial, post-ironic, totally-completely-post-Tandy Man -- yet my eyes mist over to see the old M100 once more. (sigh)

It wasn't my first computer (I've been doing this since the Jacquard Loom, though the hair transplants and monkey-gland injections make it hard to tell except in bright sunlight). But it was a LOT of firsts, nonetheless.

- The TRS-80 M100 was the first computer I ever rationalized buying as a personal productivity tool. Before it came on the scene, I had "computers I bought to automate offices" (various CP/M jobs, TRS-80 Model IIIs, minis, etc.) and "computers I bought to code games, do basic document-processing and fool around online" (Atari 800, later various Commodores, etc.) Buying a personal computer as an adjunct to _personal_ digital productivity (in something very close to the modern sense of the term) was very new.

- It was the first "appliance" computer I ever worked with. The M100 OS and general ergonomics shares a huge amount of abstract conceptual DNA with today's smartphone OSs -- under normal circumstances, it never really shut down, always maintained application context, displayed all apps and docs on a toplevel 'home' screen, let you switch from app to app without losing cursor position, had a system-level clipboard, and moved gracefully in and out of terminal mode.

- It was the first 'apps' computer I ever worked with. Folks forget that, for a couple years, there was a real third-party apps market for this thing (with cassette tapes and downloads as the distribution mechanisms). Some apps were coded in the machine's native assembler, but many were produced in M100 BASIC, which, for my money, was in many ways the most powerful and useful first-generation (i.e., pre VBasic) BASIC Tandy and Microsoft ever produced. M100 BASIC had all sorts of nice interoperability with low-level system features, smartkeys, etc., so you could make BASIC apps that worked like the native apps, and do cool tricks.

- It was the first fully-portable, laptop-form-factor PC anyone had ever seen. The perfect journalist's tool -- suddenly, I could write a 1200-word story or live-transcribe an interview anywhere I happened to be, then file it by modem from any telephone. Plus, you got hours and hours of system life from four AA batteries -- more like a Kindle than my Droid phone. Totally game-changing.

- It was, in many ways, the first computer optimized for social telecommunications. By the time the M100 came along, we were all past masters at BBSing, CompuServe, Delphi, MCIMail, etc. But portability, the built-in modem and direct RJ-11 connectivity (with acoustic coupler optional) took stuff like CompuServe CB Simulation to the next level.

Also interesting to remember that the M100 was the last Microsoft project that Bill Gates himself actually wrote code for. Now that he's (even more) rich and (even more) famous and all, it's easy to forget that Gates was, at root, a coder. But he had a fine, workmanlike hand at 8-bit microcode, knew how to crank caffeine and play sport-death with macro assemblers at 3 AM, and had (and presumably still has) an acute vision for how systems should work and how they can be useful. The M100 is early testament to that art -- so many of its features have that sure-as-gravity "Well, of _course_ it should work that way" quality about them that characterizes really crisp engineering. How ironic, then, that Microsoft can't seem to win for losing in the smartphone market, when Bill essentially had 80% of the functionality idiom sewn up, 28 years ago.

This was my first portable computer. I created some pretty elaborate proposals on that thing. It was a beautiful product on many levels. From battery life to the keyboard....Spend hours on planes flying around the southeast banging away on that device.

And being an old Radio Shack guy (30 yrs ago) it brings warmth to my heart to see discrete components again. The photo of the pico capacitor is classic.

The drive-side swap was kinda simplistic.. I masked off pin 32 (top-side, furthest from the notch between pins 4 & 6 (all odd pins on the bottom) and ran a wire from both drives, to this pin, with a 1-ohm pull-up to +5V,out to a mini jack through the case front, and the shield of the jack to the GND. Idea being, to change to the 2nd side of the drives, I simply used the command (forgotten, Yipes Old Age is setting in!) to toggle the cassette relay... Just had to remember in the program I was using, to remember which side I was writing to. I actually re-worked one of the basic Xmodem programs, to be able to write binary data in hex to separate files on all 4 sides, for huge binary files.. (used to drive an old RBBS-PC transfer program batty with the delays of writing the data.)

I edited my post of yesterday and it has now disappeared - probably for scrutiny as I added a link to photo's of the Memory mod we made for the 100 in the 80's.

Another thing I remembered of the Radio Shacks and never appreciated it till the IBM PC cam along was that the printer header was laid out as required for the centronics printer plug! So with a length of ribbon cable, an Centronics crimp on plug and a header plug, I could make up printer cables sometimes using a coke bottle as a hammer.

When the IBM PC came out, it was a shock and frustration to make up printer cables - was a real nightmare!

using SCOM to interpret raw printing data to my Zerox 460C typewriter. On my laptop you could see the global characters representing command code in the very documents I was processing. I was elated to find I could use Ctrl keys to insert these commands without modifying the document once it was loaded into the typewriter.

I could work on the PC while my clerk banged away on the typewriter; it made for a very efficient office. I still have both machines, and I just have to rebuild the battery to get the PC going again!