TRS-80, a Bit of Computer Nostalgia

TRS-80 Mod IV with dual floppy drives and a whopping 64K RAM. Note the front edge of the keyboard. Radio Shack was notorious for this battleship gray paint they used on their computer cases that started to rub off almost immediately exposing the even uglier plastic underneath. We went through this for something like 4 generations of computers before RS finally just started using colored plastic like everyone else.

I have a lot of elderly computers laying around that probably should have gone to recycling long ago, and probably will. I hang on to some of the because of nostalgia, like the one up above. That’s one of two TRS-80 Model IVs that have been kicking around here for ages now. I worked on a lot of these dopey things in the early 1980s, along with its predecessor the Mod III. All things considered, it was a pretty darn nice computer for its day, if a bit on the expensive side. And they did have some “issues”, as they say, thanks largely to some quirky design decisions made by Radio Shack that were probably done to save money.

Not exactly what you’d call a ‘high tech’ video system, even for that era. Basically it’s a cheap, generic black and white television without the tuner or audio.

They were made as cheaply as they could possibly be made (The TRS-80 Mod I came with a video display that was literally an old RCA black and white television with the channel tuner and audio circuits stripped out of it, for example.).

Yummy yummy RAM chips! Guacamole dip costs extra. Despite the Tandy Corporation brand, they were made by Motorola.

I had a couple of Mod III computers, and basically the Mod IV was little more than an enhanced III. And they were expensive. The III sold for, I think, about $800 with a whopping 16K RAM, and RS wanted an arm and a leg to upgrade it to a full 48K. (That’s all you could add to the Mod III) I don’t remember exactly what RS charged to upgrade to 48K, but it was a ridiculously high price. $180 sticks in my mind for some reason. Anyway, you could easily do the upgrade yourself for about a quarter of what RS charged. RS was selling the exact same RAM chips in blister packs at their stores. Total cost for that was about $30-$40. All you had to do was open the case, pop the chips in, and that was it.

The interesting thing is that you actually couldn’t use all of that memory even if you had it, so the memory claims were very misleading. The system ROMS (the computer’s basic operating system) were mapped into the system’s memory map, replacing the first 16 of RAM with the ROMS, so you actually only had access to 48K. If you used a disk drive, then TRS-DOS, the disk operating system, sucked up even more memory. Unless you used a non Radio Shack OS, you couldn’t use more than about 32K – 48K (which was the maximum you could have on the Mod III). So why load the computer up with memory you couldn’t use? Because RS was trying hard to push the computer at the business market, and a lot of businesses were running CP/M. RS didn’t actually sell CP/M for the Mod IV (at least I don’t think they did) but you could get it from other companies. But this was also the time when CP/M became obsolete thanks to the introduction of the IBM-PC and MS-DOS. Radio Shack/Tandy started out as a leader in the personal computer business, but because of an unwillingness to spend money on serious R&D they quickly fell behind and were desperately trying to keep up until they finally washed their hands of computers all together.

RS/Tandy sold the Xenix OS (a UNIX clone) for their business models like the Mod-6. They were bigger, better, faster, had 8 inch floppy drives and you could get hard drives for them. But they were expensive, clunky, and non-standard in just about every way. I have a Mod 6 and a Mod II laying around somewhere too and one of these days when I get bored enough I’ll open one of those up.

Speaking of floppy drives – my, aren’t those dirty… Actually the whole thing looks like it’s been sitting in a barn for the last 30 years. For all I know it was. Or is this the one that got soaked when my 50 gallon aquarium broke one night and the water poured through the floor into the storage area in the basement?

See? Didn’t believe me about the cassette tape, did you?

Those are some real pieces of junk, gems, those drives up there. Genuine single sided, double density, 5 1/4 inch floppies, those are. And holy fright they were expensive when they were being sold! I don’t know what the ones for the Mod-IV went for, but the drives for the Mod-III were ridiculously expensive. But then floppy drives were expensive across the board back then. The Mod-III was mostly sold bare bones when it first came out. You could get it ‘fully loaded’ with dual floppies and 48K of RAM but not many people bought the drives at first because they were so expensive. The ‘standard’ configuration was 16K RAM and a cassette tape player was used to store programs and data. Seriously. Cassette tape. You can imagine how well that worked.

The first drive, which contained the required floppy drive controller adaptor, sold for about $1,200. Adjusted for inflation that’s almost $3,000 today. The second drive sold for about $800.

These floppies are single sided, double density, so they could store a whopping 180K on a single floppy disk. That’s 180 thousand bytes. Not even enough to store a single average sized JPEG photo.

Oh, and did I mention that floppies back then cost up to $5 to $10 each? The company I worked for back then sold genuine IBM brand floppy disks. They sold for “just” $10 each. We’d give you a deal, $95 for a box of ten. I just paid about that much for a 4 terabyte drive for pete’s sake. But at the time I was selling 5 megabyte hard drives to businesses for a cool $5,000 each. Considering what prices were like back then I’m surprised anyone ever bought one of these things. Adjusted for inflation that hard drive would sell today for over $12K.

This is what ran the whole show, the Z80 CPU. Most of the really popular computers of the day like the Apple ][, Commodore 64, Atari 400/800, etc. used the 6502 processor in their equipment. They used it not because it was good (it wasn’t), they used it because it was cheap. The Z80 was more expensive, but it was also more powerful. It had a better register system (it had some 16 bit registers which the 6502 lacked), more registers, better indexing, better instruction set, etc. It was more expensive, yes, but it more than made up for that with its capabilities. I’m not sure why RS decided to go with the Z80, but they did, and they kept using it for a rather long time. It served as the primary processing power for the Mod I, Mod II, Mod III, Mod IV, and the Mod-100. RS did use other processors as well. It used the 6809 in its “toy” computer, the Color Computer (ironically, the 6809 in their toy color computer was a much, much more powerful processor than the Z-80 used in their ‘professional’ computers)

The picture above shows the main board of the Mod IV. This was the first time I’ve had a Mod IV open (back in the day Mod I, Mod III and Atari were the ones I mostly worked on. By the time the Mod IV came out I’d switched to the Color Computer and OS9) and I was a bit disappointed when I saw this, well, mess is the only way you can describe that board. If you look closely at that photo you’ll find jumper wires hand soldered to various points all over the board. The backside of the board is just as bad. More wires running everywhere. And most of those don’t look like repairs or modifications, they look like they were done at the factory. When I see a main board with jumpers running all over like that it makes me nervous. It means either the circuit board was badly designed in the first place, or they found serious bugs in the hardware after it went into production and they had to pull them off the line and do some pretty serious rewiring to get them working, or they were trying to make modifications without bothering to redesign the circuit board. I don’t know what’s going on here, but if I’d opened up my brand new Mod IV and saw this it wouldn’t exactly inspire confidence.

Radio Shack/Tandy sold a lot of computers back then, but it also made a lot of mistakes, some of them serious. Once the IBM-PC was introduced, RS tried to compete in the business market with the Model 6, which was, for the time, a very sophisticated, multi-user system that sported a 5 meg hard drive, and the Xenix operating system. But it was also very, very expensive and if you wanted to do anything that couldn’t be done with the very limited selection of software available for it, required you to hire a professional programmer to write it for you. They brought out a line of PC clones which had a whole host of problems and were generally more expensive than other equipment with the same specifications. Basically they did just about everything wrong that they could do, and ended up abandoning the computer business entirely. Now the company is gone completely, for the most part.

That’s all for now. One of these days I might talk about the Tandy Color Computer. That was the Radio Shack computer I was the most involved with back in the day. Despite the fact most people looked at it as little more than a toy, it was an amazingly sophisticated computer once you got past the ridiculous operating system Radio Shack crippled it with. Most of us back then chucked Radio Shack’s OS in the trash and ran a multitasking, multiuser operating system called OS9

Author: grouchyfarmer

Yes, I'm a former farmer. Sort of. I'm also an amateur radio operator, amateur astronomer, gardener, maker of furniture, photographer.

4 thoughts on “TRS-80, a Bit of Computer Nostalgia”

  1. Wow, what in interesting post! I was in junior high school when the TRS-80 came out. I could not afford one, but I had a “rich kid” friend who could, and we were pretty impressed. Of course, the average modern microwave oven has more brains than a TRS-80 did back in the day, but that’s progress.

    My first computer was a Commodore VIC-20, a name I’m certain you’re familiar with. I bought it off another friend for $200, and that included a Kantronix terminal controller and software for running RTTY on ham radio. The “software,” such as it was, was a printed circuit board that plugged into the back of the VIC. It was more like hardware with a PROM chip on it than actual software. If I remember right, you could not use the VIC for anything else while the card was plugged in because you were taking up the only input/output the machine had. That limitation was moot since the VIC-20’s processor did not have enough horsepower to walk and chew gum as the same time anyway. I eventually “upgraded” to an IBM PC-jr and did not own a true personal computer until after I graduated college.

    Like the TRS-80, the VIC-20 is hopelessly archaic by today’s standards, but wow, we sure did have a blast. Working Commodore computers can occasionally be found at swap meets for about five bucks. I have a mind to pick one up just to live my youth again.

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    1. Glad you liked it πŸ™‚ The TRS-80 line were pretty good computers for their price range back then. If I remember right the Mod III sold for around $700 – $800 with 16K RAM and no drives, which sounds like a lot but the Apple ][ was going for well over $1,000, and up in the $2,400 range if you wanted it fully loaded and a floppy drive.

      I remember the Vic 20. It was a neat little computer and pretty inexpensive. I never owned one but did have a C-64 for a while. and an Amiga, which was an amazing computer and ahead of its time. I had a lot of different computers go through the door back then. I had a Mod-I, a Mod-III, Coco II and later the III, Atari 800, C-64, TRS-80 Model 100, some Ohio Scientific equipment. I worked for a company that sold Epson and Diablo printers, CP/M business systems, and the Panasonic QX-10 computer. This was just when the IBM-PC hit the shelves and almost overnight all of the business systems we were selling were obsolete. I made a tidy side income doing CPU upgrades, minor repairs, adding memory, installing and servicing floppy drives, etc.

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