Hi Welcome to Teardown! Tuesday I Got a Bobby Dazzler for you today. Check it out. The Hewlett-packard 85 What a classic from 1979 slash in 1980. a basically well, a personal computer I guess, but it's more technically correct to call it a scientific computer really? because that's what it was marketed towards.

the professional, you know, engineering, scientific community and things like that. CRT Display: 256 by 192 know this color? Rubbish. Monochrome all the way and 8k of RAM standard built in, but that can be expanded up to 64. K Our expansion packs in the back.

a fantastic high speed tape drive. Not none of this standard cassette. rubbish, no siree. Bob This has got real high speed art professional tape in it.

It's got a thermal printer in it and this one is fully working. I Scored this baby on eBay It's beautiful, so click here if you want to see a video. I'm their pairing this thing up and having a play around with it. But you know, say you're on the Eevblog, don't turn it on, take it apart.

You can see the memory packs. I've got a ROM draw which has the wrong cartridges actually in there. I've got a 16 K memory expansion module on this puppy. It's got four expansion slots.

You can see it's like a clamshell type design. So I assume we flip it over. There'll be some screws and this whole top lid should just lift off and we'll see everything inside. It should have really good access.

Let's go. It's the serial number for those playing along at home. Now of course this will be all through-hole technology now. its surface mount rubbish and this uses all custom.

Supposedly that's not a screw or custom HP parts in it HP silicon apart from the memory and of course HP didn't make their own memory as far as I'm aware. No, that's not a that's not a screw and so yeah, it uses its own HP processor. So no, it's not a you know, as a lady or a 6502 or in thing back in like most pcs head. back in the day it was HP's own processor.

They roll their own stuff just like they did for all their HP calculators and things like that runs at a whopping 600 and something kilohertz there doesn't It's not even rocking a megahertz this thing. but it doesn't happen. it really didn't have to. It really works quite a treat and you didn't have to care about the speed of things.

That's just the fact that you could do scientific computing and this has our special functions for graphene and scaling, graphs, and doing axes and labels and things like that. It was a real powerful scientific tool and you didn't really care about the speed of the thing you cared about. You know, having professional tape that you could stalk to you cared about having all the scientific and mathematical functions and graphing capability and that you can get the printout and you can expand it and control things and everything else. so that was more important than just the raw operational speed of this thing.

So anyway, let's let me take the cartridge out and this, hopefully should just lift off. Okay, it looks like the trick here is this ejector bar has to come out. Tada. Look at that.

Beautiful. Here we go. let's try and lift the case off now. Fantastic.

Oh, we're in like Flynn Look at that Beautiful. Ah, nice and clean - love it. Wow Check out the nickel screening on this thing and look as somebody signed it. Is that? I don't know, is that the person who assembled it personally checked it? I Am Not Sure, but good on ya.

Beautiful! Oh, it's even got a date. Look Twelve Twenty Seventy Nine, There you go. Wow 1979 Vintage. There's no shortage of people actually signing this to whether or not it was some signature series it was important for some reason or there.

the production operators who signed it off as checked by the way. I found in the manual decode the serial number here the first two digits of the year after 1960. So that's 20. so we're talking.

this one was actually manufactured 1980 and the 23rd week 1980. Check it out. We have a loose washer what it's doing there I've got no idea, but it's magnetic. It's sticking there.

That is magnetic. go figure. I'm really impressed by how clean this thing is. I mean there's no dust in the bottom of it and look at the quality of the cabling in there.

the heat shrink down on the brightness pot down the bottom on the back panel. but yeah, that is really quite nice. That's a high voltage section. It hasn't attracted any dust or anything.

CRT Looks as good as the day it was built. Fantastic! There's the money shot for all you sprog capacitor fanboys. What do I find? Really fascinating though is all this look welded um aluminium bar bracket thing for want of a better term holding the CRT in here. it goes all the way down to the bottom.

it's anchored in two points there. it's got rods going like you know, it's folded back on itself and this is like welded onto there and then it forms an entire fray bracing frame which then comes up over here, down across. We've got a bracing bar across there which that's welded on and it goes over and holds the entire CRT rigidly in place. It's very nice.

Then we've got all the mains input wiring down here. You can see it and it's all nicely crimped and he trunk it very nice. I Mean you know it's par for the course back in the day, but that's all. I Professionally done, linear, transformative, none of that switch mode rubbish.

And then we got ourselves the main, our drive motor for the head. This goes over here for the printhead. You can see the see the band there that drives the head across like that. And then we've got our paper Advanced Motor Down in here North American Phillips Controls Corp Wow Look at that.

Somebody signed that as well. obviously some sort of tested Mark 12 white motor. Thank you very much. No wonder this this thing was.

You know, pretty high performance in terms of its a tape drive and also its are printing at the bottom of the printhead, stepper motor, mow, lawn motor, and coil core. but they still go in anyway. That looks like a beaut. So this board down in here is going to be our main power supply board and also its generating well.

It's got the control. Check it out. There's the darkness control for the printhead that controls you know, light or dark and that actually comes up through the flap in the top cover of the thing. so that's built in to the back of the board.

Very interestingly, if you have a look down in here, there's the mains earth Point down there. It's got shake proof, washer, and nut and everything else. It's all properly crimped, but this is actually a huge gigantic flat flex ribbon look. It's just all one big copper strap like 1 inch wide and that actually goes over to the main board over here believing on oh it's hard to see, but it's like right down in the bottom of the board, down in there, attached right down in there.

Absolutely fascinating why they've gone with like a big one-inch wide a flex ribbon there instead of just why I like they've used everywhere else. I Love this look. This is our ribbon. Okay, running from our expansion board on the back, the four expansion connectors all going over like that and look, it's just like tacked behind the high-voltage back drive of the CRT.

They're nice, but I got it. They didn't care, It's fine, wires are insulated, no worries and we got our high voltage CRT driver board. It all looks pretty standard fare and yeah, we've got a bit of a discrete logic socketed ICS over there, so that rather interesting their design that for surfacing and and all looks like with a jumper link some sort of selection thing there in a dual wipe eight pin icy socket. Hmm, there's some more interesting stuff under there.

This has got to be the CRT driver chip. You can see big forty pin dip. We've got a couple of split pins here and here holding on to that's There's a brackets on the board that then hold into that frame so if we unclip those, this board should kind of fall out at least partially and check this out, take a couple of screws off here. There's some little pivot arms and the keyboard Wow doesn't come all the way, but pretty close.

Very nice designed for servicing. Look at that. We can now access the board all I can see all the a sickie goodness. Oh hang on Yeah! and they've even got slots under the bottom here.

they can access and unclip the keyboard from and I know what you're all here to see. Show us the mainboard tada. Look at what a Bobby Dazzler all custom HP a6 every one of them except the off-the-shelf memory which is Intel Now if we have a look at the main processor board on the left hand side here, we'll find our main CPU So we'll zoom into this section here and here's an overlay from the service manual. Exactly what chips we've got here.

The one at the top, of course is the I/o buffer, and that's a dead giveaway because it's right next to the ribbon cable which goes off to the expansion header connector on the back and below. That is the rather unimpressive look in that CPU It's a smaller package. what is it? A 28 pin dip there. And the interesting thing to note about this is that there's basically no glue logic in this thing because they do custom Asics here.

so the CPU included any necessary glue logical things like that. So you won't find any support chips on here. You won't find some system glue ooh pal or gal or you know, Cpl Dior or something or another. you know glue.

ASIC chip. They actually built them into the architecture of the other chips themselves and the one down the bottom there did giveaway because it goes to the ribbon cable which goes off to the keyboard that's the keyboard controller and then you can see the power pin outs there on the ribbon cable coming in from the power supply and you can also see the signals going off to the display. So the display like there's not even a display controller thing on this board. the processor hooks up directly to the CRT controller which is over on the CRT board.

and now if we have a look at the right hand side here we can have a look at our ROM and our RAM and that's all there is. And like I said before, there is no glue logic here so we've got like you won't find a single address decoder or anything like that as you would have got in you know an IBM PC of the time or you know some other PC architecture because HP did all their own custom ASIC so they didn't need any of that rubbish. So anyway, we've got ourselves our four roms here and once again, these aren't in your traditional plastic dip packages. these are in the ceramic, gold, welded gold our capped roms like they made all these basics out of.

So that's really interesting to see that they didn't use like traditional Eproms here of the day you know, with the UV window and everything else and then put the sticker over them or whatever or even do just a cheaper plastic dip. ROM but um hey, this is obviously a mask ROM ASIC HP Had all the tools and all the technology to and all the talent we have. The tools we have the talent. it's Miller time.

Anyway, they had all of the capability to do all these a six in-house so they just did. Let's just put the roms in the same packages. Everything else must cost a fortune. anyway.

right next to that on the left hand side they do actually have a memory controller. What that memory controller are does I don't particularly know. it just controls the mapping of the main memory in this case our 16 K and that is And the interesting thing to note here is that all of these are socketed. so for ease of servicing and the if you read the service manual it shows you you know the troubleshooting guide.

If you get this error you know it's this chip at fault because like there's nothing else that can go wrong. you know, like it must be. this chip just change that one and things like that so you know really easy to troubleshoot these things when everything's socketed. beauty and check out the tape there.

They go straight up to the set and the printer there. I'm yet there's no interface at all, just drives the lines. no worries whatsoever. And the CPU doesn't just have one clock.

No siree. Bob Look a four-phase clock. No worries. And one thing you don't see on here though is a crystal oscillator.

So and maybe it's got like an internal RC oscillator. And for all you switch aficionados, here you go. Wow that we've got four wipes on each one. No worries whatsoever.

Don't know who actually made those keys, but yeah, and they feel really good too. but that's great contact. It's huge And the great thing is everything's in sockets. all designed to be serviced.

Beautiful. Speaking of which, you could actually get a troubleshooting ROM for this thing like you plug it in and you you know it can like exercise everything through the test modes and stuff like that. I Just hope you're enjoying the pan in porn there. I'm just doing that by hand.

Beautiful. We've got one lonesome trainee down there. oh but that some looks like it's going into the CRT driver board. so yeah, like they needed one extra transistor and well bunk it in.

why not? Good thing is is that you can actually take out two screws at the front here and this whole frame is basically going to lift out. But you have to be careful getting these ribbons out I've already maybe look bit of force? I'll show you and what happens here you go. I've been stuck in there a bit too long and hopefully I haven't damaged anything there. It should go back in, but yeah, you got to be real careful taking those out.

So I'm going to live that out. Have they left enough room to do it? I You bet you they have. Look at that. That is beautiful system design that you can get in there and access and repair everything.

Fantastic. And that is the complete module that's just beautiful. It comes out. the only thing attaching is the brightness control.

Obviously you can see all the the digital interface coming from the processor through those two ribbon cables. Well got ourselves a graphics processor in there I'm not sure what the deal is, but that would be like the graphics processor display drive our CRT display driver. They've got a couple of other miscellaneous ones for socket of chips. We'll take a might have a closer look at those, but there you go.

There's our light output transformer and the CRT and that's just beautiful bit of Engineering all-in-one modular frame like that. Fantastic! Be easy to test at the production stage is to replace the whole thing. The board comes out on those clips as I showed you in it I Did This is not by accident, this is just by design fantastic. And those other four socketed chips look like custom national parts.

You can see the older National Semiconductor symbol there and they've got like a HP part number I believe so you'd be able to look those up. and we can get a look at the main our power supply board. here. it looks like they do some are switching goodness.

We've got ourselves a couple of switching transformers here. We've got a power transistor on a heatsink the rest are just using. PCB is a little bit of heatsink there to end on diodes and I assume that this is the driver for the printer up here and then power just goes through this ribbon cable down here down to these these connectors. here.

they must go off to drive the various motors and things for the prenup. But yeah, all your powers running through the ribbon. The logic circuitry probably doesn't take a huge amount of power. and if you're wondering about the interface board, well, is Ted nothing on it, just a couple of custom HP parts there.

Whatever they are, they could be just off-the-shelf re-branded with HP part number or whatnot. but nope, that's it. It basically goes down right to the connectors I can show you that there we go, nothing else. As for the printer head, you can see the white ceramic head there.

the paper passes between that and that back in. Whatever that back in happens to be some sort of heat-resistant thing I don't know. but yeah, I'm moving that manually with my hand moving the stepper motor now the belt. I'm not sure what the it like.

It doesn't feel like it feels kind of rubbery, but it's not like the black rubber that you're more used to. So there has been a bit of wear on that, but it still works just fine. And you guessed it, this entire printer, tape assembly, and power supply that is going to just lift out like that. Ah, beautiful and very nice touch.

Rubber. and Eve I Bration mounts on here and they've also got those on the printer mechanism as well. Just on here. So to separate the printer apart from the rest of the chassis and then the chassis itself, then isolated from the case down here.

I Know exposed mains wiring? Look at that. Oh, it's a bit how you're doing. You can actually see the rubber mounts in there and you'll note the compliant nature of that. Just the tape drive mechanism on its own from the printer.

Now you can probably see why that copper strap made sense because you had to undo one screw holding that down. And yeah, it just comes out with the whole mechanism all formed in place. So yeah, there's method to that madness. And the whole tape drive mechanism just came off with those two screws there with the rubber mounts.

And there's our head. There's our little odd little drive there, and that's you know. It's fairly simplistic. If we have a look at it, there's a will see our controller down in there, but there's our motor.

They've just got that wires straight over to the board. It's kind of neat and have a peek in here you can see our drive controller there. it is down in there. I Probably won't take it apart much further, but there's not a huge amount of stuff on that really, but that doesn't need to be.

So this roller mechanism is really good because unlike a cassette tape, there is no drive on the individual. Look on the bottom of this like in the individual cassette tape to just drive the spool there and there. What they've got is that you can see the little spindle in there and that's what drives the tape and then the tape. What? There it is.

there. It's on the bottom half and then spindles on the top are. So there it is. There's our tape.

So in that slide. So up there we go look. it just flew, flipped open. Leave that beautiful that just goes in like that and then doesn't push in.

Ah okay, there's something that's not engaging properly there. But anyway, it would go in and the tape will go across the tape head of course and then the little capstan will or whatever you call it. Um, just drives that and dries the tape. Beautiful.

There you go, you might be able to see the tape just pushed over the head like that and if we checked it up and push down. Yeah, while I'm here, might as well give the head our little wipe some isopropyl alcohol. Yeah, that's it. Not much grow, not much crud on there.

Often You use a cotton bud for this. Here we go. Oh yeah, look at that clean as a whistle and there's really nothing else inside the know that we haven't seen before. just dad, this might are there.

We a little bit of crud, a little bit of crud, but that's about all we had in this thing. Apart from that, it's Very. It's a maybe a little bit of dust, but geez, pretty darn clean. We have a motor here just to drive the roller and which then goes up there and drives that.

and then we have our stepper motor here, which you saw before which then just drives our ceramic head across there which then heats up and it's a thermal printer of course. and we've got thermal sensitive paper, but there's no extra dry circuitry. It's all controlled from here. Here's the ribbon going out that goes straight into the printer.

Head there. I Uln 2068 There you go. I'm transits to drive her array of some description. So I hope you enjoyed that teardown of this classic HP 85 not personal computer I Prefer to call it Technical Scientific Computer Engineering computer something like that anyway.

but it is basically a computer from 1979 slash 80 like 36 years old. Unbelievable. And they would have designed this in 78 79 and it's just a beautiful design. They could have made it.

They could have made it significantly smaller. I Mean you know it's not like weight, it's not small. It was marketed as portable, but back then there was nothing else available that was portable. So hey, you got what you got.

But yep, you know this is classic like HP design and construction and things like that. so it would have been nice to see something a smaller back in the day. But well, this was still a groundbreaking machine and very, very popular. hands up if you have one of these anyway.

If you want to see me, have a play around with it, then click here. catch you next time. Credibly powerful and you can do this to label axes and do all sorts of stuff here. We're just going to label our function.

so here we go. Let's run it and it's going to take some time because remember this only works at just over 600 kilohertz, but no one cared back in the day. But anyway, here's our axes. It's automatically plotted all the the little tick marks and everything and you can probably see with this one's going to do.

But the interesting part here is is that.