Hi, welcome to Tear Down! Tuesday Yes, we're going back to the future of computer technology today. Right back to 1977. Where It All Began One of the pioneering computers of the modern era and one of the biggest selling computers that a lot of people forget about. Everyone remembers the Apple 2 and computers like that, but well, this thing was actually the biggest selling computer of its day back in the late '70s This is the Uh Radio Shack Trs8 Model 1.

If you don't recognize it, it's an absolute classic and thanks to uh, one of my viewers Ben for loaning me this thing um, so that we can tear it down and take a look at it. It's not a huge amount in these things, but it'll still be very interesting. Retro technology I Love this and look, it's fully working. No problems whatsoever.

37 years old and it boots up just like that now. way back in the mid 70s, an employee called Don French at Radio Shack actually bought one of the Mits Alir kits. one of the first do-it-yourself well, the first do-it-yourself uh, hobby computer in the world. That's what started the revolution.

He thought it was fantastic, started designing his own computer, and he eventually convinced Radio Shack that they should jump on this bandwagon and produce their own computer, which they started to design it in 1976 and was released in 1977. And you got to remember the market back in 1977. There was basically nothing out there. There were three major computers released in 1977.

this Trs8 Model 1, the Commodore Pet, and the Uh Apple 2 were all released in 1977 and they were the big three competing it out and this one actually won out at the time. and this was the highest selling computer of its time. It it it even beat the Apple 2 at the time. So it was incredibly successful, mainly due to its low price point and they really screwed the bill of materials on this one.

For example, it only displays uppercase characters and supposedly uh, that took $150 off the bomb cost which took five bucks off the retail price of the computer. So that's how desperate they were to get a really low price point and this machine was released at $600 uh back at the time. and that was just the computer uh unit itself that didn't include the monitor which wasn't really a monitor, it was just a regular TV that they called a monitor. You could have actually uh, used anything with it really.

but this is one of the this is the original monitor that came with it black and white and it was originally released in 1977 with 4K of ram expandable to 48k uh, but 4K as standard with level One basic. Although that machine didn't last long. and by the way, that machine did not have the new numeric keypad. So if you've seen some photos of this old model one and they don't have that keypad, that's a very early unit which didn't last very long as well.

They added the numeric keypad fairly quickly after the introduction of that, so this one actually has it. This one's a 1978 uh vintage unit. serial number couple of thousand as we'll see soon, but uh, then they quickly up the ram as well to 16k of ram as standard, expandable to 48k and then a 12K level two basic in ROM. That was a um, a cut down Microsoft basic from their 16k basic, it was cut down to 12K Really, cutting that cost down ensured the computer's success.

but uh, they thought that didn't sell a couple of thousand of these a year at. Turns out they sold orders of magnitude more than that, and it was wildly successful and outsold the Apple 2 and the Commodor Pet, which were the two major competitors and $600 back then about 2300 00 uh in today's money. Woo! And of course, it had stunning specs. Uh, both the Apple 2 and the Commodore pet used the 6502 processor running at 1 MHz This used the classic Z80 processor and ran it at 1774 MHz so significantly faster.

I'm not sure of the actual benchmarks, but uh, raw processor speed was actually faster than the Apple 2 and the Commodore Pet and other stunning features full stroke quiry keyboard of course, absolutely better than that Commodore Pet chicklet keyboard thing and uppercase only text as I said cuz they wanted to shave a couple of bucks off the cost uh 64x 16 character display and basically didn't have a graphics mode. although the characters could be divided up into uh, little uh, smaller pixels. so it effectively did have a graphics resolution of 128x 48 and that's what you're seeing here. I've wrote a little basic demo program and they're the actual pixels on the screen I'm turning on and off individual pixels 128x 48 black and white only.

none of this color rubbish. Now, as it turns out, it didn't last all that long. They replaced it in 1980 with the Model 3. Now there was a Model two, but that was, uh, that was earlier, but that was aimed at business users and priced at a different market.

so it effectively was replaced by the Model 3. so it only had a threeyear lifespan if that. and basically the reason for that is because it didn't meet the new FCC requirements. This thing just spewed out the RF like there was no tomorrow and swamp nearby Am radios and things like that.

and we might actually, uh, check that later on the Spectrum analyzer and see what we can see from this thing. H And this thing actually had double Precision floating Point basic. Can you believe it? Oh, state-ofthe-art And as with all Machines of the era, yes, you basically stored your programs on cassette tape so you could buy a separate cassette uh tape recorder with it. And eventually they released a Uh unit which sat under the Monda and expansion unit which could hold floppy drives.

Woohoo! So a lot of people remember the Apple 2 as being the computer that sort of pioneered the industry. Well, you can argue that this one actually pioneered it. I Mean the Apple 2 had color and you know stuff like that. But hey, this thing was cheap and it outsold the Apple 2 back in its Day by a fair margin.

So this was the most pioneering and popular computer of all time, arguably. Sorry, Apple 2 Fanboys But yeah, it was pretty much a heap of crap. Really, this model one, and that's what Uh earned its nickname the Trash 80 so to speak in the language of the ERA, this is the Trash 80 from Rat Shack Beauty So here is what you got for your 600 bucks back in the day, or $2,300 in today's money. You just got the computer itself with the power supply.

That was it. The monitor was extra. as I said, the tape deck was all optional extra. So there you go.

600 bucks bought you a well. Basically, let's go with the 16k level two uh basic machine and with the Z80 processor running at 1774. MHz With that basic in ROM booted up and that's pretty much all it did. Now this one does have some extra labels stuck on here by the owner and uh, that wasn't part of the original Uh keyboard at all.

but you know it's basically not a bad keyboard. It's a nice full stroke thing and you know, separate numeric keypad which I said the very early models there weren't There were only a couple of thousand or something at most that had the Uh that didn't have the numeric keypad in it so you know it was really quite a usable machine from the keyboard perspective and it was all built into the one thing. and well, yeah, it was built down to price and limited functionality with the Uh 64 character by 16 line display and sort of the B the effectively zero Graphics no color stuff like that. There was no sound in this thing by the way, couldn't even generate sound although with all the RF emission, you could actually um, put an AM radio nearby and and get some sarks out of the thing or hook it up to your cassette uh tape interface and you can make the cassette, uh, make sounds happen through the headphones on the cassette uh deck or something.

but yeah, but hey, this is not a bad computer at all. Full stroke keypad thumbs up. And here's the keyboard on the thing. sorry about the flicker, that's just the frame rate of the refresh rate of the screen.

uh, against the uh camera frame rate here I can tweak that? but H What's the point? And yes, this was an RCA TV and they basically, uh, just retrofitted it to uh work to be a monitor and sold it as a monitor and look, this is the original cable. There's no grommet in there I've been told by the owner who originally bought this thing that didn't have a grommet. this is how it came and you basically had brightness and you had contrast and power and that was basically it and uh yeah, black and white. only it What? Later models were replaced with a green screen one.

but this is one of the early units and I know you can't wait to see this thing booted up. So here we go. Let's turn it on. Tada Memory size I Don't know what to type there so we just hit enter and there it is.

Radio Shack Level Two Basic. Actually I Believe that memory size one is an older version of the Uh ROM The newer one actually saved a few bites by just putting mem size or something like that. and there it is. the Trash 880 Micro computer system custom manufactured in the United States of America America by Radio Shack Fort Worth Texas 76102 catalog number 26-16 This is a really low serial number one too, by the way in the scheme of things cuz they sold a couple 100,000 of these and this is, um, sub 10, 9,5, 29.

So not bad, especially considering that it was sold here in Australia. In fact, it would have been one of the very first ones in this country because the owner of this uh, his family actually ran a uh well, Tandy as it was called here a Tandy dealer in Australia So uh, they got one of the very first machines into the country and you can see the stuff through there. We can see the large electrolytic caps in there and uh, unfortunately, he's already voided the warranty on this thing. Go gosh darn it.

But it's actually not a bad design at all. They've molded in the little uh angled standoffs here so the keyboard goes up at an angle. Plus, of course you can get through to the huge huge number of ventilation holes here. you can see the board right through there, but that allows ventilation come up through here.

there's no fan of course, but uh and then vents on the back of the thing here. And here's the Uh expansion interface which went off to either the printer adapter which I do have I'll show you that in a second, all the floppy uh drive adapter, all the um floppy Drive expansion interface and pretty much there wasn't much else. that was the power button on here. real clunking power button on this soft power rubbish.

and you basically got power input uh, video and the cassette tape interface and look, they all used the same uh five pin D interface so you could accident I Don't know what would happen if you accidentally plug the power connector into the video or the tape, but jez that's just no good at all. But these these D connectors were all the rage in these computers back in the day cuz they were so dirt cheap and readily available and so common to the designers of the age. So hey, they were used in everything. as crappy as they were and curiously, there is actually a switch hidden away in here.

It's even got a key top on it I'm not sure if that's uh part of the original design but if I hit it it basically like is a Uh is a brake key pretty much and this is the original uh Centronics printer interface for it's just got the card Edge connector which plugged into the connector expansion connector on the back and it went off to your printer. and basically there's just a a couple of 74 series logic in there. That's about it. Well let's crack this sucker open I know everyone wants to see inside.

Oh a big long self Tapp of screws there. Um, it's not going to be terribly interesting in I'm afraid it's uh going to be one big board with all uh oh, these are different size screws I better. Uh, keep them in the right location. Um yeah, one big board with all dip through hole technology of course.

Classic for the day and uh I think we may have a screw in the wrong place? Anyway, Um, let's have a look at the design of it. Oh yeah, these are lengthy screws going. the okay, All right. slightly different length screws because of the angled case and uh, we should be in like Flynn in a second and they probably had a few changes.

There were mods for this thing. You could, uh, do a hardware mod to take it from level one to level two. Uh, for example. So here we go.

Let's is this going to yeah, that's off like that. No, there's actually yeah. one big keyboard. There's actually an expansion thing down here.

Whoa. Okay, there's a couple look that's a key. Must be a keyboard interface keyboard I Thought it was all on one. uh, keboard.

but gee, apparently not. Now if we take out our keyboard here, it mounts on some posts. but yeah, and Japan manufactured by Alps in Japan Fantastic. They were the Uh leaders of key switches back in the day.

kind of still are. and like I said, this is a 1978 vintage one. There it is. Copyright 1978 Tandy Corp The Uh monitor was also manufactured in 1978, and of course that would be right based on the serial number of just under 10,000 cuz this was released in O around about October 77.

So yeah, the 10,000 unit would have been manufactured sometime in 78 and the construction is exactly what we'd expect of the day in P. In terms of the PCB uh, double-sided we've got 10 roll plated tracers before it was um, the solder Masters put on top. so you end up with those crinkly and raised tracers with the uh tin Cod on them. I'll show you get the macro lens and show you that up close.

Uh, the of course the keyboard was manufactured in Japan the Alps uh keyboard. So that's why the PCB material. Everything looks different would have been done by a PS and sent as a complete module to Uh Radio Shack and they would have uh, just whacked that on there. but uh, the PCB I don't I assume would have been manufactured in the US Um, it was certainly assembled in the US and uh and tested.

and there you go. That's what I mean by those uh, crinkly traces There you can see that it's um, basically the trace. the copper Trac is all raised up because it is pin roll coed before. it's before they put the solder mask on top of that.

They don't do that these days. Of course they do SM o SE or solder mask over bare copper. but back in the day this was very common so it looked like it was all bubbling up and peeling off and the solder mask. but it actually wasn't That was the uh tin plate under there.

Now believe it or not, what's holding this board in like this is not this screw here that's just holding a heat sink underneath is actually these things. They're I don't know. I look like dried up double-sided tape. but they're not.

They're uh, something else entirely. but they rather weird. um, kind of spaces. I Have no idea what material that is.

It's absolutely bizarre, but uh oh, some of these are well and truly stuck on I Certainly didn't expect to have to dig into something like this to try and get a board out, that's for sure. This one is the only one left and it's crumbling or starting to draw some blood there. and uh, these boards. You got to be careful.

You slip your the um dip pins on the bottom extremely sharp. You can really give yourself a nasty, uh, nasty cut with a little bit more persuasion. it did actually slide off, so we should now be able to lift the board out Tada from the case and we're in like Flynn And this is actually a beautiful PCB Why do I say that? it looks a bit? H There's a few hacks and bodges on there, but it's basically very well laid out and is very typical of the era. And my hats off to whoever laid out this board.

because I can't see a single jumper link anywhere on this board and that is always the Holy Grail of any PCB layout engineer is to basically get zero jump link so you've only got a double-sided board like this. It's not like they've given you the luxury of four layers and you can have a big ground and power plane and everything else. No, you've only got two layers and they've basically laid it all out in very traditional style. Uh, for a double-sided layout out like this, in nice rows like that all the chips sort of line up in beautiful uh columns like that and they've arranged it so that there's zero jum links? there might be I don't.

Well, I can't see one. I I will will stand to be corrected on that, but that is. it's just beautiful thing of beauty Joy forever. And the actual circuit design? Very typical of the ear.

Of course it's not like a sink which tried to reduce it all in. Gat Arays down to a couple of chips and things like that. they were uh in the future in the 80s. but Back Then Basically you got the Z80 processor here, you've got your RAM and you got your ROM and everything else is basically just standard.

74 uh series. What is it? LS Yeah, 74 LS Series Logic Pretty much everywhere else, there looks to be one particular device which is not standard and that's the only one which is socketed by the way. so we'll have to have a good look at that one. And curiously, these are obviously the Uh ROMs here.

and they've taken. that's what that board on the back there is. So they've taken this ribbon cable with this uh dip header here off to that board on the back. That's the level two ROM upgrade cuz you if you bought a level one, they would actually uh, upgrade it for free I believe if you send it back to Uh Radio Shack they would do the hardware upgrade to upgrade it to level three.

That's why when flip it over, we'll see a few Bodge Wies on the back room enough in those two sockets. So they needed the expansion board on the back and there you have it. couple of uh bodge jumper wires going from various points over here over to the board with uh three ROM chips on here. Let's take a closer look at those.

And by the way, just looking at the routing on this back of the board, they've done a really good job. As an experienced PCB guy who's done many of these countless uh, double-sided layout boards like this, you can tell they've got this pretty much right and optimal. Trust me, it's not easy laying out a double-sided board like this and well, they've done really well. Manufactured by NEC here.

these are our mask ROMs and you can tell it's a ROM set because they basically got this part number you've never heard of and then a B and C there. So yeah, it's a three part ROM set. And of course it needs Uh three ROMs here to make up the 12K ROM So these would be Uh 4K each 4812 Beautiful wo there's the money shot. look at that Mosc Z80 CPU none the Z8a rubbish run at 4 mahz oh no Siri oh 1.77 4 thank you very much.

Is that a date code in there? look 7905? So this maybe this isn't a 978 unit but a very early week 9 Uh 79 because they you know these things wouldn't have been sitting around in stock right? These would have gone straight out. so this thing probably only was manufactured. This machine like maybe a couple of weeks after this chip was made would be my guess. So if we look at some of the other date codes here yeah, like late N you know 38th Week 78 50 First week 78 this one very early 79 as well.

so it looks like yeah, the first first you know, dozen weeks of 1979 this was manufactured and likewise for the Ram as well. There it is. classic TMS 416 Yeah, the 6 week 79 in that classic ceramic package. Oh I Love it.

They're vintage stuff and these are one of the early uh Dynamic memories they're not SRAM which was, uh, typical of the very early uh computers. so that's why you could afford 16k back then in uh Dam and the- 30 there that indicates 300 nond access time slow as a wet week. And check out the pins on this Z80 here. look at that.

they' gone all uh, all tarnished. Have they or is some some of the plastic sort of leached out I Don't know what's going on there. and that Motorola chip, as I said, is the only other odd ball one out that's not standard 7400 series logic here. So it's um, an Motorola 80467 bit of a Google on that.

Turns out that's the character generator chip and it was the same one apparently still used in the model 3. So yeah, that would be some sort of uh gate array holding the uh, various characters for presumably only the uppercase stuff. and we got ourselves the main regulator there on its own little uh, low profile heat sink. It's probably good enough.

Didn't hear any uh uh complaints about this thing over H him, but I stand to be corrected. Anyway, it's the 2N 6594 PMP part in a standard 203 package and well, that was a common way to mount. Still is a common way to mount 203 packages onto a PCB like that, so no problems whatsoever. I Don't like this? Uh, freestanding tip 29b just hanging its ass out over the edge there? Jeez well.

I guess if you're not living life on the edge, you're taking up too much room. We got a couple of big ass electros happening there. Look at that. 10,000 mik? thank you very much.

along with a 2200 mik 35 Vol one Cy But hey, this thing could suck. A lot of juice though. I mean these? uh Dynamic Rams here. take half a water pop and there's a couple of crusty old pots there to uh, tweak your cassette inter face, make sure you have your tongue at the right angle.

And there's the main Crystal 10.6 45 MHz So that was divided by six to get your uh main processor clock which is precisely 1.77 4083 repeater. There you go was slightly above. the sucker was overclocked from its nominal 1.77 4 Meg Beauty Well, it's no wonder this thing didn't meet any FCC requirements and basically they had to, uh, stop selling and replace it with the Model 3. Because of that, they couldn't get it uh certified? I Mean you know you got no, uh, ground plane in this thing to take care of anything? Probably the power layout is.

you know, it's pretty standard for the day, but maybe they didn't have enough. uh, decoupling on. But look, you know, when you start adding memory interfaces big parallel buses running like this I mean go. You're just asking for it and your expansion interface.

Basically, just once again, you got long, you know, long unshielded ribbon cable just going off willy-nilly to your expansion box. You can't have that. And there's no uh Metalized shield in inside the case. or anything like that is nothing.

Hey, somebody signed that. Have they there you go? Love it. But uh yeah, not none of that so no good whatsoever. Don't see any uh chokes or anything else on any of the Io lines.

Not. It's just not happening. And for those who are Keen here is the back of the monitor. There you go.

Manufactured 1978 Oh how crusty this thing is Unbelievable. And for those who absolutely must see the crust for themselves, oh hey, look at this. a beautiful look at that. oh yeah, that's got 1970s RCA written all over it you beta and that is the model Ktrr 124 Sa.

Oh yeah, look at some of that some tagboard app action going on down in there with that resistor with a lead wrapped over it holding it in place. Oh man Woohoo! This is fantastic stuff. Sorry about the uh handheld work here. Oh yeah, but hey, I guess we shouldn't knock it.

It is still working after 37 years so well you can't complain. and apparently no, it hasn't been repaired. This is Factory original. Okay, let's have a quick look at this on a spectrum analyzer.

I'm going to use the Uh Tech Mdo 3000 here so I've got nothing connected on the input I got 0 to 10 MHz span here and uh uh resolution. uh filter of 300 htz and that is our Baseline There it is basically all below Uh- 105 Dbm. So there you go. there's nothing at all.

and if I now plug in my an ten it'll take some time because of the uh narrow band filter there. but look at that. Tada there we go. There is our second harmonic right there.

1774 MHz Time 2 roughly 3.56 mahz. By the way, as far as the antenna goes on here, I've just got one of these whip antennas I Could probably, uh, move it down like that or do something. Woo There we go. Our noise floor just, uh, jumped up fairly drastically.

Let's keep it like that actually. by the way, this thing's really slow to move these cursors. It's a dog. When you've got the Uh filter set such so low, it's got to muck around and do a lot of processing and it just basically just locks up the Uh front panel control there really slow.

Anyway, there is the fundamental 1.76 MHz there's the second harmonic and so on. and I've changed the resolution bandwidth to 10 khz hurts there and you can see how it's just much more responsive on the cursor now. Oh, a little bit of a jaggy in there, but basically work in real time. So yeah, it doesn't like to be doing any heavy background processing there.

You can see all this crap down at low end here. I Mean it's just all like, you know, sub one megahertz and uh, stuff like that. It's just garbage and that's why the Am broadcast band is just being swamped and there's from 0 to 2 MHz with 100 MHz res resolution, bandwidth filter and you can't even call up the bloody menus when this thing is just chewing all that doing all that processing at that very narrow band filter right down at the bottom. a It's just painful.

it's practically locked up. really. I mean I Ah no, it just did something then sporadically unbelievable. And just because we can, let's compare the Spectrum with the Trash 80 Model 100.

Uh, rumored to be the last machine that Bill Gates ever actually wrote code for. So I'll run a little uh program here just to Loop it through and we'll see what we get on the Spectrum. So there we go. I've got the antenna directly over the thing.

Um, you know this is just McKing around. Really? So uh, no people complaining about that. I'm not doing it right, just mucking around. But look at that.

Pretty clean compared to the Uh model one, that's for sure. especially down at the low end here. there's not much happening there at all. Where from 0 to 2 MHz again with a 300 Mega 300 HZ resolution filter and that there is actually running a program that's just running a hollow World program.

it's just printing Hollow world again and again. So relatively clean compared to the model one. And if I expand that out from 0 to 10 MHz There we go. we can see the main processor clock there 2.4 MHz This is an 80085, so it actually runs faster than the Trash Aen Model one.

So there you go. That's the Uh clock frequency than the second harmonic and so on. and watch this. if I uh, switch the model one on Here we go.

So we got our Baseline of our Uh 102 here. so switch that on and Bingo! look at that jump up very very significantly Huge jump there and that's jumping up a good 10 maybe 15 DB there cuz we're 10 dbm per division. So it's not really surprising as we''re seing in the tear down and uh, by the way, I'll link in the tear down for the Uh Tandy model 100102 here which I've done uh back as well. It's not surprising that the model one here is a much noisier, a much bigger emitter than the 100 series here.

This sucker not only did it have you know, huge bus lines running everywhere, but we're talking about not the huge current consumption in just the dams. For example, as I said, those dams will take like uh, half for what a chip or something like that, that means huge big current spikes in there. and when you, uh, include large current spikes with big loop areas inside there and like power Loop areas then well, you know it's just going to emit pretty horribly. Where is something like the Model 100 here? really low power one? using SRAM We've got much lower current spikes on the Transitions and things like that, so really, you know, no surprise whatsoever.

And yep, I'm still trying to get over how awfully dog slow this thing is on those low resolution bandwidth uh settings. It's just it is practic. almost unusable. Unbelievable.

I Don't know what the hell they're doing in the processing architecture of this thing, but oh, they really need to fix it. I Know you actually get the Spectrum analyzer plugin for free on this thing now, which is yeah, great, but jeez, at least get that working. Unbelievable! A So there you go I hope you found that retro tear down as interesting as I did the Trash 80 model one. Ah, does it get any more classic than that? Unbelievable.

Let's break our little program there and CLS and list. Ah, it's just. ah, too good. Oh, by the way, I didn't show you the uh power adapter.

There we go. It's just a big Trash 80 power adapter. Um, a big linear uh Transformer by the way of the damn thing. and there you go.

I Had fun looking at this and I Can't believe it still works after 37 years or whatever it is close enough to that. Unbelievable. Still works like the day it was bought out of the box. Fantastic.

How many other computers can still claim that? Terrific! Anyway, if you want to see the high resolution tear down photos of this I usually take highes photos there on Evev blog.com that'll be linked in down below. And as always, if you like tear down Tuesday Please give it a big thumbs up. Catch you next time.