Hi! We love vintage computers here on the Eevblog and I've got a Bobby Dazzler for you today. It is one of the biggest flops in personal computer history. It is the IBM PC Jr.. Don't call me junior, Don't call me junior.

Hey, some of it in the original shrink-wrapped packaging. We've got the original box and everything. Let's check it out. And this personal computer abomination from 1984 is the IBM PC Junior.

Of course, after the phenomenal success of the original IBM PC released in 1981, they wanted to get into the home computer market because the original PC was flat out a business machine and priced accordingly. It just virtually no one was using it as a home machine, so they wanted to compete against the Apple 2 the Commodore 64, which had come out more than a year earlier than this one. actually. this one was announced in late 1983, but didn't come out until March 1984, and it was priced at six hundred and Sixty Nine dollars for 64 kilobytes of RAM or twelve Hundred and Sixty Nine dollars for the one we've got here, which is the hundred and twenty eight kilobyte version, But it didn't come with the five and a quarter inch floppy drive which we had here.

In fact, it came with no storage. No external tape or disk storage at all. So it might have been a reasonably priced at six hundred and Sixty Nine dollars in 1984, but only if it came with a reasonable external storage. which it didn't, So that was one of the killer blows right off the bat.

Now, one of the things that this computer is famous or notorious for is the keyboard that came with it. Unfortunately, we don't have it here, but here's a photo of it. It's a chiclet style keyboard. Chiclets Meaning it's got like the little square keys on it and just a membrane it wasn't you know a proper tactile keyboard.

It just uses horrible little Chiclets membrane keys and IBM just got so hammered this they had to finally release this one. which is actually it was quite innovative for the time when. not only is it you know a proper keyboard, it's not as good as the original IBM ones, but you know it's pretty good. You could still type on it, but it was actually wireless and that's what the wireless sensor down here is for.

and that was actually pretty innovative for the time. but you could also connect it via this lead over here. So a wireless infrared keyboard a bit. Apparently a lot of people had trouble with that so just adding insult to injury on top of the ridiculous chicklet debacle.

So anyway, yes, this one has turned yellow so that would be the bromine in the plastics very common for computers in the 80s to turn yellow like this. So not only was at 1200 $69 for the 128 kilobytes version which you had to get because the video it didn't have a proper video card in this like the IBM PC had. It actually shared the system memory. so you know the 64 Kilobytes was not only limited in terms of that, but also the video hardware actually are stole CPU cycles for the Refresh and everything else, so it was apparently notoriously slow.

It does have this same a at 800 AD a processor as the original IBM PC run at 4.77 megahertz, but as I said, it's stole I think one in every four clock cycles for the video for that. So it actually ran slow and it didn't have direct memory access DMA in it. Oh, but it wasn't all bad because one of the interesting things you can see down the front here is that they actually had to cartridge slots. They're just, you know, standard card edge connectors in there you might be able to see and these two cartridge slots are avoided.

The problem with the shared video memory in this side in this thing, and you can actually hot plug the cartridges in the front like this and would actually reboot the computer and boot directly from the ROM cartridge. So that was quite novel. but because it never took off I don't know what was available. The cartridges Mm-hmm Nothing.

Some people think the IBM PC Jr. runs only about this much software, so wouldn't they be pleased to know that PC Jr. runs over 50 of the most up-to-date word processing programs, over 25 mailing lists, and 15 database programs, over 60 programs for personal finance and home management. There are 15 programs for communications and another 15 for the stock market, over 200 for general business, over 300 for education between programs to help you write your own programs, and hundreds more to help you do almost anything, plus powerful new cartridge programs like Lotus 1-2-3 The truth is PC GU runs over a thousand of the best, most up-to-date programs and with its new memory expansion attachment, it can run well over a thousand more.

PC Junior from IBM the computer that's growing by leaps and bounds now actually rather like the design of this. It's small and compact and you know and didn't take up much space. It looked, you know, fairly professional and everything else. It had the side expansion packs which we'll take a look at at the back and and but one of the things is is that while this was small and compact, look what you needed clunk a big 56.

What mains transformer? But if that external power brick wasn't enough, What? Why You had to get one of these power expansion attachments and it just so happens that we have this here. look at this in its original box tada and that came with yet another. Ah, Power Brick. Another power brick where you actually plug this into the side of the unit over here and this would provide extra power because the power brick for the main machine wasn't presumably wasn't enough.

Might have been an engineering goof. They might have thought, oh yeah, we're good enough powder power these expansion PACS over here which had extra memory in parallel ports and whatnot and then when they tried it, they went now yeah, we don't really have the power budget for that I Know we can design and this you just plug the power into here and provide additional power for the extra expansion adapters don't So another interesting thing was this side pack attachment and they've just got a big point. One each had a connector along here and you could get things like Tada a parallel printer attachment. Why they didn't include a printer port on the main unit I don't know.

Anyway, they would just plug into the side like that so it's a little bit kludge, but you know, whatever. Anyway, this one's interesting. This is a 512 K memory cycle. This might have been aftermarket thing, might have modified by John Bishop Good on you Dawn from Marietta in 1989.

So this is way after this machine was discontinued, was actually only lasted about a year and a bit. It was discontinued in 1985 so it was just a complete flop after selling 200 and or shipping 270,000 units I believe it was. But anyway, this is actually the 128 K memory expansion pack which does actually have the DMA controller built-in so if you plugged in the side memory expansion pack, you would overcome that issue with the video-sharing the memory inside there. So we're going to standard a Hundred and Twenty Eight K pack, but looks like this one's been modified so this one was a fully loaded beast at 640.

K No one had ever need more than 640. K Check it out! I Actually found one of the original cartridges. it was squirreled away in the bottom of the box and made in USA Version 1.00 Thank you very much! My cartridge basic and this one actually over wrote the well A supplemented the internal basic or whatever that supported more at Han't enhanced modes and things like that. But yeah, it's great.

But check out inside here. they've actually filled that with sponge. Ah, that would not fare well in with time because that that spongy stuff is notorious for. like degrading that cell.

You know the cellular foam type stuff just degrades with time. but mm-hmm not sure they were trying to do their Oh Check it out, it's a mask ROM Know that. EEPROM Rubbish now on the back here. Well, it did come with actually quite a decent array of peripheral and expansion ports and whatnot.

People didn't like the fact that they use these non-standard point one-inch headers on here. I Mean basically the only standard things on here are the composite video, a connector and also the audio over here audio jack over here. so let's have a look at the port's it's got actually came with two joystick port switches are pretty good. El is actually a spare so I don't know if it was ever actually used for anything.

K is for keyboard if you wanted the wired keyboard and didn't want to use had a crappy infrared thing. LP is for the light pen tears actually for television believe it or not if you didn't want to use the composite video. but it's also got D is for direct video which we'll take a look at in a second. s is for serial.

so it didn't use a standard like D 9 or D 25 serial port. You had to get the adapter cable which by the way came in its own box. Look at that adapter cable for serial devices has probably extra. No doubt you wouldn't get that for nothing from IBM and C is for the cassette interface here.

but if you wanted to drive your Armanda I'm not sure if it actually I'm sure if you bought the monitor it came with it. but there was the big box for the IBM color display for the adapter cable. but check it out. in true IBM fashion over-engineered look at this: I Am genuine I Am P connectors.

Thank you very much for playing fantastic with a shielding on that. What a Bobby Dazzler They've really kind of town on that adapter cable just for the monitor. Awesome! And of course that wouldn't actually connect to your monitor. It just converted the Bloody Point one inch header to your standard D nine here.

Unbelievable for those playing along at home York Awesome! Oh, and it is, Of course the model number 48 64 those playing along at home and contains copyrighted code Wow you will listed so you know what we say. you're on the Eevblog. don't turn it on, take it apart. let's go.

Doesn't seem to be any screws on this thing unless they're under the AH the feet. They look hard to get off, but looks like there might be some clips or something. Let's give that a bill. Yeah, no worries.

Oh, look at we're in like Flynn Beautiful. There's our expansion boards, power supplies on an expansion board. Check that out. It's not too dusty and it's a neat enough arrangement in there now.

of course. famously it does not use. The standard is a IBM expansion connectors because you know they didn't want to eat into their PC market that they were dominating at the time. So yeah, they deliberately are domed this one down.

Now it was actually the PC junior was actually technically cloned in quote marks by my first computer, the Tandy 1000 and I've done a video on the 10 you 1000 I'll Lincoln at the end and down below as well where I design a turbo board for the Tandy 1000. but the 10 he 1000 overcame all the issues with the IBM PC Jr.. Used standard is a expansion slots and even though the PC Junior was a complete not a flop, the Tandy 1000 was actually very popular and a lot of games at the time actually had a attendee 1000. Graphics supported the Tandy 1000 enhanced graphics mode which actually came from the saw some of it I believe came from the PC Jr..

So there you go. Even though this was a flop it did morph into when you know you didn't use proprietary connectors and all sorts of other crap. when you actually made it PCI compatible then it could have actually been a success and it was for Tandy. Now thermally our fan is actually in their pan are flowed for those panel laying along at home and of course the air intake is at the front comes across it's got a sort of make its way around this card I don't the floppy drive controller card so when you put that in it just kind of.

it's completely screws up the airflow. But anyway it does suck it out from here and blows it out the back. and they've got this little low guide thing which attempts to sort of spread the area out across the grille. Here, it's not great.

Let's have a look at the power supply here. it's not too bad at all. It's only a single sided hard edge here. You'll notice the big large multi peanut contacts on there.

For the current that'd be the ground, there'd be plus I think it's just +5 volt and ground on here and there you go. Old school square layout, but you can see that it's only a single card edge contact there. And basically we've got two big switching regulators here. SGS L-29 six hechas and this one's - fire.

So that would be the five volt and this is - twelve. So that would be the 12 volt switch and convert other guys you guys looking inductor. they're potted. They'd have another one up here that looks fully fully encapsulated, fully potted.

and it's just the output fielder caps they're made in Japan Good stuff. We've got a heat sink on the diode bridge on the input, but it's not. This is not mains our voltage at all. Of course this is just I think it's sixteen volts AC in and that's all she wrote.

So there you go, that's gonna be pretty reliable. Then we've got an additional wire power cable here. it's just running across the top of the board. It's a little bit how you doing I believe that's going over to power the floppy drive up there.

Yep, that'd power the floppy drive and then this looks like just the fan control. They go in well antenna I Don't think it's temperature controlled I Think it just provides power to the fan and we have another board here. I Don't think anyone ever made a PC Jr. compatible like physical machine.

Please correct me if I'm wrong. But there you go. there's our additional memory expansion board. That's the extra Arab 64 K to bring it to the Hundred and Twenty eight.

K And as you can see, there's no DMA controller. Nothing on there at all. and there's no other sixty. There's no internal 64k a ram down there.

And as I said, one of the reasons this thing wasn't popular is that it was particularly slow, even though the Four Point Seven Seven Megahertz 808 E8 was a pretty pretty good for the time, especially in May compared to the Commodores and the apples and stuff. But yeah, it was just like crippled. So in terms of our sharing, the memory, and also I believe there's reports that you couldn't even use the keyboard when the floppy drive was been accessed or you couldn't The serial port didn't work properly when you know it was doing something. So yeah, it made some engineering choices in this thing to try and cut it down because they didn't want to eat into their PC market.

Oh I Forgot to mention before. Um, this is quite novel built-in modem, but it didn't come with that. You had to actually get the modem card extra Novation Inc IBM not IBM Design There you go and eight to five Oh Yep, but Saul that's IBM custom is it? Well, it's got the IBM partner and could just be an off-the-shelf part, but Novation and they've got maybe they're two customer gator or something like that and of course the telephone line isolation transformer and whatnot. That's about all she wrote.

Um, yeah, there you go. Don't know how much extra the modem cost, but hey, you know that was a good touch if you could get that built-in especially like because people who would buy this would be business people who just want a home computer but they don't want to spend. You know, pony up for the full IBM PC at home see at the PC junior and hey, you might want to tie into some system or something. so a modem.

That was a nice touch. And over here it looks like we might have a dedicated infrared board which is on standoffs off the main board. Hmm, it's bending how you doing. And there's the floppy drive control.

It doesn't really compare to the was one does it? but yeah, I'm sure it's a bit more advanced. The original machine had a single side of 360k floppy in it, but this one might have the 1.2 Meg high-density one. so I'm not sure. but yeah, it originally came with 360 K I'll tell you what.

I Rather liked the design of how the floppy drive goes in there. There's the plastic clips which are actually on the bottom of the case and you just push those in and it goes through the matching holes on the PCB and Bob's your uncle. That's a it's a nice bit of system design there. Now we can have a closer look at the floppy mechanism here.

I Love a good floppy and we can see that it said I won't take the plastic cover off couldn't be bothered. it's an Alps FDD 26 24 BG one for those playing along at home I don't know whether what density that one is I Love it how they have the spindle speed encoder chart on there so that you can get like timing chart so they can get your strobe in there and figure out the exact timing cuz you have to calibrate these. you have to get in there and go with your tongue at the right angle. Where are the trimmer there and they might trimmer pots might be on the bottom side or something for that.

anyway. I'm not sure whether or not this of what density this one is, but I do know it's double sided cuz that's definitely a double-sided head down in there and of course we're up. I can lift that puppy up a little bit. Um, and we've definitely got the to our shielded cables coming out there.

one for the top head, one for the bottom head. so no worries, that's double-sided floppy and the belts in there and they still looking good Nick So well I reckon this thing add does still work a treat and the case is actually nickel screened. so RFI fur RFI shielding reasons and of course that is completely conductive and there you have it. That's not a bad looking board.

It all looks like it's a four layer job. We've got the classic: our ground and power to all be virtually all five volts and I think there's another rail on there. You know there'd be maybe the odd 12 volt analog or something floating around. but yeah, ground and power planes in the middle are.

We've got all the traces going in this direction on the topside. If we flip around I'm sure we'll find they're all going in the opposite direction. Vertical like that. That's your classic two-sided digital layout like that.

So that's a very nice looking board. I Like that there's no budges on it. There's no nothing how you're doing on there whatsoever. So if we go in we'll have a more detailed look.

But where's wally? Where's the processor jobbies down here? There it is. Let's go have a quick squeeze. Tada for all you fan boys, see a toe 88 There it is that's a genuine Intel job. Eat Now! I Do believe that IBM were paranoid back in the PC days that it was a single the Intel chip the 808 E8 that the head bit their entire line of pcs on was a single source chip from Intel.

So I think they pretty much strong-armed AMD and maybe one or two other companies to actually licensed the manufacturer of this so you can actually get AMD branded Intel processors. go figure and this for the infrared board. Geez, that's a big infrared transceiver receiver. It's just a receiver.

Wow You know, compare that to a modern infrared transceiver. Cheese little surface mount shall be no contest, but they go into the effort to were shield the bottom of that board so they're really and I being outside am red tape galore. so they're you know they take EMI seriously. Alright, let's check out the board, shall we? I'll do this a little bit different.

I'll do like a screen capture talking head shot here on the PC instead of talking behind the camera like I normally do. So let's zoom in. By the way, I As I said, I Really like this board. It is quite professionally designed and professionally laid out and manufactured.

It just feels like a serious computer motherboard as you'd expect from IBM It's it. You know, different to the pcs of the day is just much better. It just feels you know it's the warm, fuzzy, much higher quality sort of you know, industrial computer rather than you know slap together in Singapore that all the Singapore back in the 80s was the place where all the cheap stuff was made and Taiwan as well instead of China these days. of course China wasn't the thing back then.

Anyway, it just feels really professional is about. so let's take a look at it. Of course. We've got our 808 E8 Intel here as we mentioned and our requisite you know, jellybean blue logic all around here.

this is all seven, four, LS stuff low power Schottky A pretty standard for the time you know nobody who was using HC HC around back then I did everyone was still using LS it was still the thing. So anyway, supporting that is the interim 82 of Five Nine. This is the interrupter controller and here's the datasheet for that classic and of course 808 E6, 808 E8 compatible. but it comes from the Intel 8008 E5 series, the 8-bit architectures and that was of course the advantage of the Intel 8008 E8 is that it effectively had an award had and 8-bit bus.

It was a 16-bit process internally, but it all that all the peripherals in the bus was accessed in 8 bits so you could actually use what Intel could reuse. This was a big part of the success of the original. IBM PC is that kind of reuse all their existing 8-bit peripheral chips which they had and they are making for everyone else so you know it just made sense to use these. So yeah, that's your standard PA your programmable interrupt controller and above that we've got our cells are the Intel / AMD manufactured by AMD As I said they AMD second source.

They had a license to actually manufacture the IBM chips back in the day and that was a thing because IBM you know they want their second and third source for all these parts. They don't like themselves unless it's them making it. They don't like themselves up tying them into one manufacturer. and of course IBM Big Blue.

You know he carried a lot of clout back in the day. so Intel we're very happy to give them license anyway. the 85 three let's go to the Datasheet classic programmable interval timer so added it had have all your timer modes and things like that which you use for maybe joystick control and things like that, the time, how far you know time, different things and stuff like that. very important back in the day.

Of course all these separate peripheral chips are all like integrated all into the yeah the chipset chips these days which is so familiar with on the motherboard. Back in the day they didn't have these dedicated chipsets which put them all into one. They have these dedicated chips which you have to use so that's the PA Once again, 808 E5 compatible MCS 85 compatible By the way, if you're actually interested in that MCS 85. The MCS 85 was actually an Intel system design kit for the 808 E5 processor that they had back in the day and this would allow you to actually you know, figure out how all the chips work, is individually programmed, the addresses and you know, experiment with these chips until the cows come home.

That's why why they would have that was the original system design kit, so that's why that they would actually have this MCA ID 85 compatible. That's where it comes from. And next to that, we've got the Intel RP 8255 the Classic programmable peripheral interface. So let's go to the datasheet and take a look at that.

Here we go and it had programmable IO pins allowed them to interface with any other miscellaneous IO that they wanted to hook up to on the machine so that was. You'd find that in practically every you know computer it'd be at IBM or whatever it was. The other processes at the time would have their equivalent to the programmable peripheral interface so that it just allow you to do read/write control to various ports and nothing special. It was just a way to access stuff on the CPU to access regular IO pins on the bus.

So equivalent to a micro controller these days where you know, except it has all these built in. You have IO pins built into your microcontrollers these days micro processors back in the old days they didn't You had a data and address bus which you had to hook up to these IO controller chips. Essentially okay, let's pan around up to the corner up here. What are we got? haha.

We know in a chicken dinner it's the classic triple five timer or in this case the five of eight. the Quad Triple five. Time of the five six was the jewel. Five Five Eight.

was the Quad, and that would be no doubt being used for the joystick port. That was an absolute classic. So how that would work is that the adjustable pots, the adjustable potentiometers, adjustable resistance on the joystick parts would actually feed into the Triple Five timer and actually control its pulse width. So then you could or frequency it's And then they use the timer counter chip to actually figure out how long that pulse was and you could figure out the position of the joystick And that's how they did it.

It was very common, it was used in every PC back in the day I'm not just talking about IBM PC but a whole slew of other personal computers as well. And let's have a look in the top corner here, because here's an old friend. You might be able to guess what this one does with the proximity to the crystal. Yes, it's the clock generator chip used to generate the processor clock, but not only that is also used to generate the video clock as well.

In this case, it's going to be a fourteen point three, one eight, one eight megahertz. I Believe that's correct, megahertz crystal, which is actually divided by three. So if you go fourteen point, three, one eight, one eight, divided by three to give you your four point seven, seven megahertz IBM PC The Classic IBM PC clock. But if you divide it by four, then it also happens to give you the Three Point Five Eight Megahertz video clock as well.

So that's a effectively I Think why they chose Four Point Seven Seven is something that they can use the same clock. I Think the 808 E8 was a traded to five megahertz or something, so that could have pushed it a bit higher, but then they would have needed a second crystal second chip all that sort of stuff to generate the two different clocks required. So they actually shared the crystal. So I Think that's where the history of the Four Point Seven, Seven Megahertz clock actually comes from.

Because if you I think if you read the datasheet, let's go have a look, shall we? And today? Yes, there it is. Five Megahertz for the 808 E8o, eight megahertz for the 808 E82. So they could have actually pushed it to five megahertz in the original IBM PC But hey, what cotton cost on this thing cost was, you know, reasonably important. I'm trying to get it down and it's nice engineering.

You just share the two 4.77 near enough to five Oh worries. So let's just pan around a bit more, shall we? Nothing Doing Nothing doing. they're all just the interface Sum up the top. Let's actually go down a bit more down here.

you more. R74, Ls3, Seven Threes, nothing doing there. Nothing interesting. What's that Krustyburger there I'm sorry I didn't like I Wiped off a few of these chips.

Anyway, here is the Roma and this is interesting. Look, it's not sucking it, it's soldered directly onto the board. said not only is it a mask ROM no this EEPROM Rubbish. It's directly on the board.

Date code: 8th week 84 there. so that was actually before it was officially introduced in March 84. So there you go. They were pretty sure about their bias code, so good luck upgrading your bias on that puppy.

You got Addy Soul the chip from a full layer board. Oopsie. And then we've got 8mm twenty three to five six which is Tada A, once again another mask ROM It's a 256 K bit, 32k by eight and that probably contains the the basic and the DOS because I think it had dos in Ramat didn't it 2.01 or something like that? Awesome. That's where it would be.

It's not in the same chip as the BIOS I don't think. And then here's the expansion. Kinect decided the cartridge connectors down the bottom. so yeah, but they look to be tying straight in so I'm not sure where like and if they had any hot bunkers as you saw I mean you believe you could hot plug these things in I automatically detect and reboot and everything else and I'm not since seeing any really major protection stuff for hot plugging and things like that so maybe that was a bit.

how are you doing back in the day? but I believe that was the thing to do. Anyway, let's go over here and have a look at the RAM Now this is the 64 Krm. It's a remarkably few chips because it used 64 K the 4-1 the classic for one 64 of course which is the 864 K by 1 bit and they've got 8 of them which gives total of 64 K bytes and you'll notice that is only eight. There's not nine, so there's no parody on there.

so if we have a look at that, it was available in Sip & dip this is. this happens to be the SIP package one that was common back in the day to see our sip packages like this, but they had the room on here. they didn't have to use the SIP I don't know. Maybe the dip was cheaper? who knows and I'm not sure what this Motorola part here is the 1503 seven-to-three it's you know.

Copyright: IBM I don't know I'm not going to put any more effort into searching for that one. Maybe I don't know. Did it baby? Handle the infrared stuff? Infrared comms for the keyboard? perhaps? Not entirely sure. Let's go up here.

this is an interesting one. What on earth is this 1503 730 more IBM part numbers? Now if we actually have a look at the technical reference manual here, yes, I'll provide a link in down below. It's got everything in here. So yeah, great bedtime reading If we have a look at the block diagram here, then it's got.

Look, it's got some weight state logic down here. It's got a MMI logic and stuff like that, so maybe that's what those are custom and gate array chips there are actually doing. You know they might have a couple of custom parts to do that, perhaps? Okay, let's go and find the Seventy Six Four Nine Six. Sound chippy, shall we? Seventy Six Four Nine Six.

Ah, Where is it? Where is it? Where's that sound? There's that audio up there. Ah, there it is. Seventy Six Four Nine Six, This how sound. It's not much.

Is it? What is a three voice? It's a simple three voice thing or something like that. nothing special. And of course all your video was handled by your Classic MC 68 Four Five here. and this was used in I know half the computers in the nineteen, the late 70s, early 80s kind of thing.

It was just everywhere. It's just your regular CRT controller and of course it could do 80 by 24. you know, text and stuff like that. and it was 6800 compatible.

So I'm not sure when it first came out, but it it is. You know it's it's pretty ancient and yeah, it's what can you say. it's a 68 45. And of course you've got to have your serial port our controller.

So that one here it is Classic 82 Five-oh serial controller which is now. All these things are now embedded inside the modern chipsets. It's still more embedded in there to you know, get all the serial ports and whatnot on your stand pcs These days they're integrated in your Northbridge yourself preach with a bloody chipset it is I don't know and it's it's classic. It's the National Semiconductor job' It wasn't the National Center it was an actual yes, a genuine National Semiconductor beauty.

And yeah, it's it's the serial you are and that's it. Too bad they used a dodgy bloody connector on it. You know, like that, like couldn't put a standard Dena liner Adi 25 on there. Unbelievable.

I Do believe that's pretty much all she wrote that looks inner and that looks like it's like a black hole. That's like Bank Bonus: you pay more to get a black hole in your PCV So that's what you need for the IBM PC junior. And as I said, it's quite a well laid out board. Look, all the chips are in the same direction.

all the traces are all going in one direction, all the young ones are going in vertical. On the other side, it's a beautiful layout. I Like it and it's you know, just users all off-the-shelf in well know. As we as we looked at, there might be a couple of custom gate arrays in there, which might have definitely got the parts count down, but there's lots of jellybean interface logic, lots of sets, all pretty sure it's all 74.

LS Sometimes they'll use like a 7 4 F somewhere if they haven't like, you know, really fast like propagation delay problems or something like that, you might see one or two of those sneak in. but in this one I think it's all pretty much LS Yeah, Anyway, there you go. I hope you liked that kind of detailed look at the main board in the PC Jr.. it's neato.

so there you have it. I think I'll leave it at that. Always gotta look into maybe RTFM I Read the manual about the error and things like that. Get into app.

you can see that the hardware still works. The classic IBM A PC Jr.. one of the biggest spectacular fails in the personal computer history and really it was just a complete and utter flop. But as I said, like the the Tandy 1000 sort of derived from this and was a success.

and I got my start on a Tandy 1000 which I'll link in the video about here right at the end of this. Check it out! So anyway, if you enjoyed that, please give it a big thumbs up. That always helps a lot with the engagement and all that sort of stuff on YouTube and hopefully that won't team monetize this one, but geez, I've got a no running list of videos demonetised now. It's hilarious anyway.

And as always, discuss down below on the Eevblog former in the comments: I usually when I make a video live I usually like in like the first hour is sort of like the best time to get me for comments on videos and stuff like that anyway. I hope you enjoyed it. Catch you next time.