Hi Take your mind back to 1972 when Texas Instruments made more than chips? Look at this bad boy. Ah, the silence 700s upside down so all the electrons are gonna fall out. Portable data terminal from 1972 cuz back in 1972. Hey, like time sharing computers were all the rage, right? We didn't have personal computers back then, so you needed like data terminals to connect into time sharing computers.

So let's have a look at this bad boy. Texas Instruments Oh, look at that thing of beauty is a joy forever. And yes, that is an acoustic coupler modem. Fantastic.

And this bad boy was advertised as being three times faster than competing terminals. How fast? Why to be lightning fast if it's three times quicker? Well, 30 characters per second? That's characters per second. But if 30 characters per second, it's just too fast for you. Well, you can whack it into low speed mode.

Probably down to what ten characters per second? I Love the here is key. What? leave it in the comments if you've ever used. I Here is key, but the keyboard is absolute classic. It contains a ton of stuff.

About the only one I know is like Bell, you know acknowledge stuff like that where I'm sure we're all tree useful for the terminal market and logging into like time sharing computers and stuff like that. but I love these. like because which in the upper case. Oh, they do the art stuff.

You got to remember this is not a computer at all. It does no internal computing and processing apart from like the serial interface basically talking to a serial port or through the acoustic coupler modem on the top to some form of time-sharing computer eva via a durum presumably could have like direct connected it up via a series or you hook it up via the acoustic coupler modem and it doesn't even have a display. It's got a printer, so everything that you receive instead of going on to a screen, it goes on or prehnite. So that's nuts.

And it goes to show why this thing really didn't last much beyond like the early 80s the Wikipedia page. Yes, there is one for this series of Ti Silent Seven silent series. our terminals was that yet they survived for a bit longer When modems started becoming like 1200 board modems. This thing literally could not keep up.

Not because the electronics in the serial port couldn't keep up, it's because they couldn't print it far. They couldn't print the characters fast enough on the paper. The actual printhead. the thermal printhead in here couldn't actually print long enough.

But they did actually release one with a dual printhead that could actually print twice as far. So and it's it claims are used into the mid eighties. but I like apart from very niche old-school apps like I Doubt anyone was using this past the mid eighties who supplied by a computer benefits? it's still around. and this was pre eight digit phone numbers I Can remember when I had to change over from a seven digit to an eight digit phone number here in Australia they made it compulsory but in computer benefits like computer with benefits Wow It's got a contrast pot made in the United States of America beautiful and there's not much.

On the back, there's an IAC power connector. there's a non-standard looking serial interface presumably and those are rich in the armboy back on fake on waster you I still work at PACOM Yeah, that was my first job actually. and for all you young kitties out there that don't know what this is, it's an acoustic coupler modem and it went over the phone handset cos phone handsets used to look like this you know with the coil, II called and everything else used to connected across here and I would generate tones and it would receive tones on here and that's how it did it. It sent it through the phone line as little beeps and you could send you know like well, 300 board, 300 bits per second was you know, huge back in the day and then it went to 1200 bits per second.

1200 board. ah that was. you know, black magic cuz you've got to remember the analog phone line has and still has like a very limited bandwidth so it's actually quite difficult to get more than like a few hundred board down a phone line without doing. You know real fancy techniques which they invented over the years and you know, I would like to get like your fastest which was like 56.

K There may have been ones that were a little bit faster, but anyway, like the 56 K which quite a lot of you will no doubt remember and probably anyone still using 56k dial-up anyone? I'm sure there are anyway that uses really advanced our protocols to fit everything into the bandwidth. So anyway, this is quite common and of course it accommodated different sized handsets like that body just loved playing with an old-school acoustic coupler. It's great. anyway.

I'm going to power this bad boy up before I take if it still does anything. So here we go. There's mains in there, sir. Power Switch: Oh oh yeah, look the heads moving.

So obviously it's got some sort of echo thing happening where my stuff occurred. Then what? I'm typing echoes under the keys, but it's obviously not doing anything. Return there, We go. there we go.

So hey, this sucker works. but obviously the thermal head is not working and it's not. It's not advancing. So I'm not sure what the deal is.

line feed paper, advanced file, but it like it's going through the business. Look at the yellowing on the plastic from Ola from the fire retardant and flathead screws. No miss. Phillips Rubbish.

Oh Papers still in great Nick By the way, Date Code: October 1978 Fantastic! Oh Lease It's a lease job at least this bad boy and the use of paper not meeting Ti specification may void warranty. Warning: Will Robinson And here we go. I'm afraid this is not going to be the most interesting teardown on More In more intrigued by just the just the novelty of a terminal like this. and oh, look at that optical encoding will Wow So that does your positional movement for your printhead.

so that'd be like each individual character, each individual individual position. and you drive and go next character next character bit. but this is hilarious. This was what was making all the noise and not sure if you heard it but sorry, that's hilarious.

Somehow it blows air into here out of that. I Don't know, it sees me like blowing it over the paper. What? This is just hilarious I Don't know why that's funny, it just is. an Asst Prod Capacitor fanboys go wild Oh Fantastic.

No wonder they still work. Oh Tip 41 Power transistor just stuck on with the mica washer and the how you're doing thermal paste. Terrific. I Think you think we've got a 79 series regulator in there? Probably got a 78 series over there.

Probably another couple of trainees stuck down there as well. Just like on, there's just little aluminium vertical heat. That's the business. As for the PCB no this solder mask.

rubbish. We've got Tim plate of course. and with the black silk screen just directly on top of the traces, No workers state-of-the-art flat flex going over to our printhead. There we go.

There's the rest of our board under there. As you can see, it's basically no processor in there. it's just gonna be a serial interface and printhead driver. That's it.

And you know. keyboard decoder. Check out the pudding type gunk there got down there I Don't know why they decided to whack it on just that top bunch of components there. I'm not sure what the deal is.

Ah, check out the mains input. what's doing here? Anyway, we do have a input mains fused. Check out the three kilovolt ceramic caps in there. Just love the old school nurse and they've got the heat shrink while the insulation tubing over the leads as well thank you very much.

Looks like there's a common mode choke going on down in there and presumably what. This is a weird-ass looking trend I Assume it's a transformer. What? Anyway, this is the main switch to3 power there I'm off hand I Don't know it and that's J 7432 Yeah, 78 dark mid. All the components in here are: Mid 78 datecode nose.

You want to see the base of that. They've also where they put that gank before. They've also put some on the bottom side here. so I like was Moisture a problem at that part in the circuit? I'm not sure.

made in the USA T I Love the TI logo. Classic. Anyway, there's no obvious budges on this board, so nice job. Whoever did the layout on that? Sweet awesome dust accumulation from 1978.

I Presume it's never been cleaned. and they're They're all series power transistors. Probably you've been used as a series pass regulation elements. Actually looking at all this.

I Think this is all part of the power supply here and given that this puppy is not your standard linear transformer, it looks like this is a switch in, not converted given that the power this thing would be taken to of course it need a fairly decent a linear supplier, then we've got a big-ass switch in supply here. and I think you'll find that these two big-ass caps here are 240 volt direct as in 240 volt AC much higher DC volt. I Think it's got direct mains rectification and your traditional switch mode supplies. That seems to be a lot of quite a bit going on.

Here are all our discrete transistors on this integrated circuit? Rubbish going on in the switching power supply. So if I can find a find a schematic for this thing. Um, because yeah, it looks power supply looks fairly involved. that's of a song.

Look at some of these puppies down here where you'd expect to find our TTL we've got T I Of course at ER Gonna win me huh with the bomb for this thing SN 98 Six One four I don't know those offhand I Don't know what the unpopulated socket is there, but all these other like little A Punjabis up here they're all Op amps and whatnot. So I would presume that all that is part of the bit detection. You know, level detection and bit detection circuitry for the serial interface. Let's get this keyboard out of here.

It pops out of these little plastic holders. No, Oh no, Oh no, it does have this microprocessor. rubbish. I Was hoping to do everything discreet with some character generator roms, but no R4u 8080 fanboys, look at that genuine TI TMS 8080 from 1978 Beautiful I Know you want the close-up There it is isn't a thing of beauty and it's got hot snot on either end just to keep it in.

Oh I Do believe that's a single wipe socket. Two evil things they are. and we've got some TTL 7 4s series because they needed the extra speed in there just for some sort of interface there. I am gonna presume that this puppy down here is a mask ROM cuz I don't see a ROM anywhere else.

So yeah, we've got some 7 4 LS stuff around here o 7 for ill aha they didn't want to piss away the extra current with the LS series. They didn't need the speed so they went on well. put in the low power version. thank you very much.

And what's that crystal up there? 12 Meg By the looks of it screaming I don't know what that other forty Punjabi is down in there I Have to look her up and the keyboards made by my croissant Illinois Were they the Ducks guts back in the day I Don't know. Leave it in. the comments: The keys do actually have a beautiful tactile feel to them. Oh oh, is that an inserted pin mistake? You notice it? Yeah, it's been out there.

or is that a genuine open pin mod. Hmm I think that's an insertion mistake. So maybe that pin didn't matter or pins matter. No, it's socially connected.

It: Yeah, it's connected to a trace. but I think I was making contact and if you're gonna do an open circuit mod, you would definitely bend the pin out horizontal. Definitely wouldn't bend it back under like that. I Stand corrected slagging this poor thing off.

potentially having single wipe sockets? No there. just watch out your wipe in the vertical Form factor: Wow You don't see many of those. Let's just plug this thing back in when it's opened up. shall we don't return line feed.

Hey, we're feeding the paper now. So I actually plug that guy. bent that pin back in and plugged it in. So I don't know.

Was that a Whoa. Nice. but thermal print heads not working? No, but it. the process is obviously working and it's responding to stuff.

So yeah. Dull. I'm an idiot forgot to plug the printhead in like the thermal printer. It's moving, but it's not connected.

Don't try it again. Oh yeah, it's there. It's there. I Think it's printing something.

Maybe just see that very faint I Love it. Yeah, line feed. It just literally just feeds it. Yeah, you can see some of that like there's one line of dots there so it looks like only one of the one pin on the printheads working.

Oh five ohms impedance protected just to show you the other side of the mechanism here. I Don't know why that's got that. sort of like just flapping around in the breeze at the end. there.

not sure. was that supposed to push it or screw on? Not sure what the deal is there. Anyway, that looks like. oh maybe it that me, you can see the head see the head moving out with that.

I think I was all the way on I think it was touching. Did manage to get a couple of characters up there, so maybe the printhead wasn't against it. but it doesn't seem to be actually printing characters anymore. So oh I don't know.

This thing's a bit temperamental, but wait. I Found the service manual for this thing. Let's take a look. I Love the old-school service manuals.

I Just love these old brochures. Check these out! Listen: I Only 1995. The only weighs 13 pounds. It's half the weight of the currently most popular portable our own Model 735.

This is the 745. This is great and Oh surprise it didn't ever rotary dial. Fine brilliance that I had a rotary dial fire when I was a kid. she's writing to my teens.

probably Young Whippersnappers new portable data terminal from TI 25 pounds 2595. Love it. How does she type with fingernails like that? I she doesn't. It's the answer look.

she looks. she looks so happy walking to work. I'm carrying a 35-pound It's great stuff. 30 characters per second.

twice as fast. it's sorry. three times faster than the competition Texas Instruments Incorporated. All right.

But here we have the service manual. This is the 1978 edition, so our maintenance manual they call it and these things are so comprehensive. they don't do this anymore. just be amazed at how much detail they're gonna have in this.

I haven't looked through it all, but I'm sure it is massively comprehensive. Full-duplex they're explaining. Yep, full and a half duplex and all that sort of stuff. because you know people have to.

Well, technicians have to understand this stuff, how the paper goes in the platen. all the rest of a theory of operation. Nobody does a theory of operation anymore. Give me the old school magazine projects like I used to right back in the day and get published and you'd have a theory of operation of your circuit.

You know everyone publishes their open source stuff these days. you almost never see like a theory of operation anymore. You never see a block diagram. You never see anything like that.

So gone are those days. It's a real shame. 110 board, 300 board and all your ASCII tables. You control codes and whatnot.

There's the printhead driver. There you go. Contrast is 0 to 75 milliamps ceramic heat sink and there's the printhead element driver. Well did we see those mate? Um, that.

Let me go to the power supply section because I might have been wrong about those tip 41 transistors. They might be the printhead drivers because I didn't see them near the connector. So I think they're way back up. and there's the printhead stepping motor that with the wheel that we saw with the photo transistor.

nice as the pre dead stepping motor driver Look, it's all there. This is all the theory of operation. There's your character set which would be burned into the mask. wrong because we didn't see into that.

Ypres Rubbish in here. and and there's all the like. all the other codes and everything. Jive Rarely used more than like a handful of those really.

Even back in the day when you control G still works as the power supply converter. voltage ratio failure protect. Soft start. Ah simcha, soft start.

Fantastic. Look at this. Here's all the theory of operation just for the power supply. Fantastic.

The 8080 So comprehensive. Then we got flow charts Wow Brilliant! I Thirst Acoustic. There's the frequency shift keying for the I Thought they only use frequency shift keying at the 1200 board. Oh yes, no, of course they did frequency shift keying.

Maivia There's two separate frequencies. they you. they're two separate ones they use. There's a transmit and receive pair with two different frequencies each and that's how the 300 board worked from my rusty memory.

I'm sure everyone will tell me if I'm wrong. I'm not gonna bother to check that and I like it. You know, live and had two Kilohertz or something. You know? now we're getting into troubleshooting.

Checklists: Fantastic. Like this is brilliant stuff. Look at these like they're gonna have lots of exploded diagrams. - I'm sure this everything's got its own part number.

Yeah, here we go. Now we're talking through this. Beautiful. we've got the bomb.

Look at. you know it's huge amount of details gone into this. Some people drew this and then checked it and then triple check that Fantastic. I was still doing doing hand-drawn stuff like this at yeah yeah, we're still doing it sir Cell: So we're still doing it like I'm talking 12 years ago.

probably not that long ago. we were still are Maybe okay. like I say 15 to be safe. but yeah, like 12 15 years ago I was still doing hand-drawn documentation like this on sheets and we'd have to fight it would after we'd have to master copy.

Then we'd have a photocopied copy which was on a different part of the site just in case half the building burnt down or something And then we had an off-site copy as well. and all these huge A3 folders. I've still got some of the original Cecil grid paper like tallies and so sell and other companies that I've worked at. It was all.

what wasn't one big company change names like four times anyway. I was still doing that not that long ago like my job previous to our tiem. stuff like that cutting pasting using glue, just stick stuff onto the A3 sheets and stuff like that. we're still doing that.

and then if you wanted to make changes, you took the original you photocopy that you added got progressively worse with this revision. It was great. Anyway, look at this. No, this overlays fantastic.

The heatsink assembly, how to tie down the capacitors I think I saw there. Now we're talking we getting into schematics now. Look if I give you the pin outs for the chip. Fantastic Yeah, do that anymore.

Here's an overall block diagram: receive current loop, low power supply the interface reference Wow that's all the PC Well, the in piece of a hello. Here's your power supply. There you go. This is why it looks so complex.

Here's your mains input. You can see the cursor. You can just see the cursor. Here's the cursor up here and as common mode choke four ways bridge rectifier Yep, some high voltage caps.

no where are they? Oh yeah yeah. Five five hundred volts. There we go. Got our high voltage caps and that was the weird ass transformer that we had there.

It's a custom job with all these different windings and bingo on the output on the secondary side here has no linear regulation, so there's no linear voltage regulators on the output of that. so they're just driving that directly from the transformer. There's no feedback path to that so it's forward referenced so fail protect, latch over current sense. all that sort of stuff.

So all those transistors that we saw they have to be I reckon they're for the printhead driver. There's nothing else in there that would require a so many of those transistors and be require them to be on a heatsink. So I'm sure if we go down, there's your TMS 8080 and your ROM everything else. Brilliant piezoelectric sound disk.

terrific keyboard and mechanism interface. Let's have a look. Printhead Stepper Motor: Aha, there you go. Tip 41 B's Lar Yep, yep, so they would as a Shum on a Heatsink 12.

It's got 12 next to it, so that probably points to a heatsink somewhere else in the document. Yep, So there you go. That's what all the driver transistors were for and us Acoustic Coupler Modem originated mode. Hands up.

If you had to switch the answer originated switch, Yeah, difference. Integrate a carrier detect. There you go. So that's all.

I was right. That's all those Op amps and stuff that we saw in there with the whole bunch of diodes and caps and resistors and other stuff. That was all that part of it had to be there was. There's no other reason for that to exist.

So yeah, you got your bandpass filters. so you'd have to have a couple of bandpass filters and you have to carry a detector. You're a sieve clamp, difference integrator. The whole works.

So all your old school analog modem got to oh or different standards. That's us. Acoustic coupler Modem originated mode and this is Ccitt Acoustic coupler modem originate mode, right? This sheet applies to assembly, blah blah. There you go.

It's got this. Got the frequencies in there FS Case 1650 1850 There you go. receive a transmitter if garb here. Oh, they're up to 2200.

What? 22 I Don't remember it being over 2k. Okay, not for 3 on the board. Wow Originate mode Japan Japan's got a different standard. There you go.

So that's a change this board. I'm surprised they didn't put it on like a daughter board or something. Gee, look at all the notes. Wow Unbelievable.

And look at those exploded diagram. That's fantastic. Absolutely fantastic assembly. Wow Yeah, that's terrific.

How to put your washes on, how to assemble it? Fantastic. Yeah, got got the foils. got the copper foil artwork. but there you go.

That is brilliant. Is it not? Oh more more? We've got a different power supply, do we? Wow Wow Okay, it's looks like the schematics for multiple versions here. So yeah, and then you get into the case and everything else or your assemblies stuff like that. Look at that.

They just don't make service manuals like that anymore. That is absolutely brilliant. So hats off to the designers back in the day. Well, it's just so much effort you know to draw nice schematics like this.

You know it really is a lot of effort. So there you go. I Hope you enjoyed that. Look at this silent 700 computer from the 1970s, which is it? No, it's not doing a computer.

No, it's not a computer. It's just a terminal that doesn't even have a screen. You know you had to print it on the paper and you have to continually waste. Majan if you ran out of paper and no I can't read what's coming in like unbelievable.

sigh Man of paper, they would have wasted. so yeah, you would have been. You know, like it's just like a single line screen would have a. Well, no, it wouldn't have been handy cuz then you wouldn't You'd have to scroll back all the time so you'd need like a you need like a CRT kind of thing.

But these portable damage data terminals did the business. so let us know if you actually used one of these puppies back in the day and how important it was. So anyway, I hope you liked that video if you did, give it a big thumbs up as always. catch you next time!.