New LCD for Old TRS-80 Pocket Computer 

For context, I am 52 years old. When I was a kid, these things hit the market, and you have no idea (or maybe you do) how badly I wanted one. It was extremely expensive at the time, and my parents laughed when I wanted one. You, in just one video, have fulfilled a childhood dream!

The BASIC program lines are not limited to the length of the display. I believe it has a maximum length of 80 characters per line, and will scroll side to side. If you use the PAUSE command instead of PRINT it will briefly display the text on the screen and then move on without waiting for you to press Enter. And it's funny you went to the trouble of manually typing in the value of Pi, when it has a dedicated π key. Also there's a hidden key: if you press Shift-Y it'll display a Yen symbol (¥).

The display is glued and this bonding is breaking apart. The adhesive is based on uretanol. This adhesive removes moisture from the air and so the glue loose its bonding. At our museum we already switched over 2 displays from a sharp PC-1211 (which is basically the same model as yours shown in the video). I'm afraid of our other 3 Sharps, they have the old display and I hope the glue is still intakt bondig the glassplates together. Nice Job!

This channel is a hidden gem.

Your enthusiasm for random tech is so refreshing. I'm absolutely here for it.

I literally have one of these with this problem. I had ordered the replacement LCD and thats been sitting next to it for months. This is the kick in the butt to finally do it.

I had this model, back in the 80s. Very cool to see it being restored. I flipped the polarizer over to get light characters on black. :)

Iceland Calling, I bought one of these as child in the 1980s. I was out of my depth, but inspired by the BASIC programing and portable computing of this machine. Thanks for this!

The battery situation is easy to explain: the original 4 batteries where 4 mercury cells, so they had a lower rating, the whole thing is supposed to work at 5.4 V, not 6, so with modern batteries you either need a diode or three of them.

The whole thing of sound is data was fairly common on 80's machines. I grew up with the Sinclair ZX Spectrum and it worked the same way for storing and loading programs from tape. There was even a radio station in Poland that would broadcast a program for you to record on tape and run on your Spectrum.

Oh, now you MUST create the interfaces for it! Your idea with a microphone AND one to transfer from the phone through the headphone jack. Search your feelings... You know this to be true!😂

Those strips on the LCD are what they call "ZEBRA connectors". One of the mundane magic things is that it's actually a multi-sandwich-set of conductors. It goes conductor-noncond-conductor-noncond-etc.., but in VERY thin vertical strips. This means that there is many conductors to one pad, much like a single wire has multi-strand sub-wires. This means that should one single conductor fail, the rest take up the slack.

Great job getting the new display working. Regarding the logic - that's almost certainly not ECL - the power consumption would be horrendous. ECL uses bipolar transistors which are not driven into saturation to allow very high speeds. Instead, I would expect some early CMOS or hybrid NMOS / PMOS implementation.

This is so like the Sharp PC-1350 that I inherited from my dad 36 years ago. Still working perfectly witrh an externel contrast thumbwheel! Its powered by 2 No. CR2032 Lithium cells with a separate 16k "credit card" sized RamCard (with its own CR2032. My dad used it for "in the field" Life Assurance quotations so the Math accuracy would have been good enough! It got me through an engineering degree, with its external thermal paper Printer (which can power the unit with AA batteries). This unit also did the audio interface to a compact cassette tape and CMOS to TTL level conversions. CLOAD, CSAVE .... innocent times....

I did this on an old Sharp PC-1251 about three years ago. I don't know why these displays fail, but I love that someone out there cares enough about them to be making replacement parts for them in the 21st century.

This is what I learned BASIC on. Subsequently, I only know how to make random number games and I can’t go over 544 bytes.

Awesome. To bring this baby back to life. Really impressive. Working on old technology could be very delicate. Filming and working at the same time. Really awesome. Keep up the good work.

IIRC the reason the old LCD reacts to your polarization lens but not the new LCD is that the old LCD and camera lens uses linear polarization while the new LCD uses circular polarization internally (LCD's can be built using either). We know they're linear polarization because they react when your rotate them, circular don't do that, instead you get the slightly shimmery look (due to no linear polarization being prescent, so it's random). Both types of polarization are still used for displays, it varies depending on the display type (TN, IPS, MVA) and manufacturing methods. IIRC IPS always? uses circular polarization so it's much more common now (most but not all displays use IPS or IPS variants now). Polarized sun-glasses is another common example of linear polarization, they want to filter out ground or water reflections which is roughly linear due to reflecting off a flat-ish surface. The first LCD screens on the local busses where I live were completely unreadable with polarized sun glasses because they didn't think of specifying this when purchasing them and the cheapest panel happened to be linear AND the final polarization layer was orientend so the screen was black-on-black with polarized sun glasses - you could see it fine through the sun glasses if you held them in front of you rotated 90 degree, confirming what was wrong. Later bus displays were carefully specified so this didn't happen.

So glad that there are folks making replacement LCD displays for these lovely little machines. There are so many Radio Shack PC2's, Sharps etc that have decayed displays. It's so nice to see these little things brought back to life!

The triumphant joy in your voice when that display comes on... priceless!

Cat toy laser pointers can be a good source for LR44s in a pinch, I think they include 3 of them. If don't have any on hand, walmart usually has the laser pointers w/LR44's for cheap in the cat section. I couldn't find any LR44s themselves at walmart so that was my only quick/cheap option once haha.

One of this things I love most about your videos is your passion for some stuff that I 100% DGAF about, but your enthusiasm and genuine desire to share your information makes every video you post a joy to watch.

I have this exact same pocket computer. I remember looking at it a few years ago and noticed it had the same damage on the LCD. I just figured there’s no way to fix this. Glad to hear someone is making LCD screens for them! I might end up repairing mine as well. I do have the cassette adapter as well. They also made a little printer for this pocket computer as well. Thanks for the video!

Also, the filter you removed provided additional pressure on the display, for the contacts to be reliable. I wonder if you have sufficient pressure without that filter - which you would replace with just a glass panel of the same thickness.

The connector for the cassette interface would be analog audio, in & out and possibly a pause control. You should be able to build a connection to a phone or other audio recorder.

I can get a pack of 4 LR44 / A76 / 357 for $1 at the local dollar store. I see DigiKey have them for $1 each and those are name brand ultra schmeck Murata batteries. These are also Canadian prices. They should be pretty much free in the US. Where on earth did you have to pay $22 for 4 of them???? Nice job on the retrofit! I had one of these back in the day. My zero (0) had a stroke through it and the "O" did not look like a vertically flipped "Q" as yours does. Strange.

Nice, I worked at Tandy Electronics in Australia back in 1983 to 1985 as a teenager and had this pocket computer with the printer and cassette interface. Great times !

MAN! What an effort to save this 80's piece of tech. Congratulations to you and all the other people making the replacement parts. I hope you get the other stuff running again too.💯👍😁

I noticed you don't have any shorts videos, I hear they can be surprisingly lucrative and the tape save signal over the speakers would be a good one!

The dreaded zebra strip! I remember the original Pebble smartwatches being notorious for the zebra strip for the LCD failing, causing artifacting on the display. Simple fix to unscrew the back of the watch and clean the zebra strip, but it was a pretty widespread problem. Great video as always!

That conductive pad gave me flashbacks to the PSP-1000's analog stick connector. I always hated those things

I keep an old PC1211 in my basement. It was purchased in 1980 and it was given to me by my boss while being a trainee engineer. He owned a second unit and wrote a small pricing program for the company products, using this toy at 99% of its capacity. It was a 5 hours job in a train travel and was used by the company for years... I had so much fun and great service from this tiny computer...still in my basement...and I gonna fix it...if I can!

I've never not had a battle with the zebra strips. There is apparently some sort of magic to get everything aligned the first time but, at this point in life, I'm losing hope of ever witnessing it. Thanks for showing us some nice skills and a really cool computer system!

Loved this repair, like a lot of other commenters I really wanted one of these but never had one. It was fun following the progress on your livestreams.

I have a similar (display is smaller) Sharp PC-1245. I built a cassette interface for it since the Sharp one was too expensive for me. I've also captured the audio from the Sharp training tapes that came with it. All on my channel if anyone is interested. The display on mine is still in perfect order, surprisingly enough.

Thank you Shelby for not referring to it as an "LCD display" lol.

These replacement displays are made by Robert Baruch. His youtube channel has a number of tutorials that show the step by step instructions for replacing these displays. I've bought several from Robert over the years, and I am really surprised he is still selling them for a measly 20 bucks.

I had one of these in high school... It was awesome to create basic programs. Then bought the fold open pc-6 for college... :) loved those things..

That CASSETTE data signal sounded like either an ASK or PSK signal (due to the constant 4 kHz carrier during the transfer). Recording in Audacity, only the amplitude changed during the symbol changes (with a powerful 3 kHz high-pass filter to remove DC noise), and the phase didn't change, so I suspect it's an ASK signal. ASK is quite common and very simple to implement for a quick and dirty cassette audio interface. However because the receiver relies purely on amplitude, it is very sensitive to noise inducing errors (even just DC noise). FSK and PSK are much better and have stronger resilience against noise, as the data signal characteristics are different from the noise characteristics (e.g. looking for only frequency or phase, means that DC noise doesn't matter nearly as much).

I had one of these in the 1980s. I loved the ability to enter long equations, test them, then go back and edit them. This was not available on most calculators at that time.

There is a place in my heart for that, as it was my first computer. I learned BASIC from the excellent manual it came with. Unfortunately I sold it when I upgraded to the PC-2 (which I still have).

My Fluke 70 Series II has the same type of LCD. Cleaning that conductive strip with 99% isopropyl brought mine back to full contrast.

Your excitement is awesome!

My first computer was a TRS-80 Model 100. It fit neatly into my locker in my barracks (USMC). But I have never even heard of these before.

one issue with zebra strips: sometimes they take the shape of the tracks on the PCB side, causing them to not be flat anymore. So if in the reassembly process this side of the strip is on the LCD side it won't make a good contact. So pay attention to the orientation of the strips

I had a psion pocket pc back in the 80s it was awesome

I had one of these when I was a kid, and it got tossed out because of this issue. We assumed that there would never be a replacement screen, since even in 1992 (I think?) literally NO parts of any kind were available. This is amazing.

That was fun to watch, that was my first computer, I bought it new. I also have the cassette interface and player as well as the printer. I was tough using a 2" wide printer but it was a great learning computer.

I had this and worked/studied with it for a while. I was creating my own little program and it worked really well. In short, it was a little Excel program or formula in itself.

Great video! I always wondered how the LCD connections worked!

In the early 90s I wrote a program on one of those that figured out the theoretical RF power of a mult-tower AM radio antenna array. I had the printer that went with it, used thermal paper I believe. It worked very well but they are very clumsy to program and you have to make sure you don't waste any RAM. I think I had something like 10bytes left. Thanks for the memories.

Robert Baruch created these replacements. He has two cool videos that show the process he went through to. He actually had to re-design them from scratch and do a deep dive.

It's fantastic to see these new displays being made, I'll be holding out for Sharp 1350 and 1248!

i was lucky to get one of these in 1980. I still have it and it works like new. It has a lot of hours on it but Ive not seen any screen issues yet as i do check it every year or two. I actually learned basic on the bigger desktop version of the TRS80 in 1979 and i still have all the programs i wrote. Kind of useless in the real world today. Hopefully I wont need to do this but I might have to pick up a new screen now just in case! Thanks for sharing this!

Brings back memories. I had one back in the day. Don't know where it got to.

I had the SHARP version of this as my first computer . I also had the 4-color printer plotter for it. I was able to program it in assembly language because SHARP made a reference book explaining how to.

Man, I'd love to have one of these! Also TIL what that mystery switch on business calculators actually means! Thankyou!

Hi Shelby I purchase LR44 batteries at the dollar store. Package of 4 for a 1.25. I enjoy your videos and enthusiasm!

23:11 RadioShack invents NFC. LOL! Love it. So cool if it would have been true. Thanks for another great video.

No, the display does not use ECL logic, which is (or rather was) a very high speed, very power hungry logic family used for mainframes & super computers. This device would be 100% CMOS logic. My best guess at why it needs a split power setup like that is because back in those early days of LCDs, they needed weird bias voltages, possibly including a negative voltage.

I bought one of those from Goodwill for $5 but it came with a docking setup and printer.

The Excitement is Awesome! Great Job Sir!!

Wow, I last monkeyed with one of those bad boys in the late 80's. It had a color printer: one of the selling points was you could use it to plot data and equations. The whole affair (printer + computer + recorder) fit in a small briefcase and constituted one of the first portable computers. These are the days of miracles and wonder! Or so we thought. In retrospect it was more like rubbing sticks together to make fire. Or Gordon Gekko on the beach phoning Bud Fox from that chonky beige Dynatak.

I remember using a similar SHARP computer where I programmed it (Basic language) so we could use as a Rally race computer by my navigator guy. Sweet times.

Lr44 expensive, really? Those are almost as easily available as cr2032, and mostly they are even cheaper.

As a yough man i wanted this desperatly , thanks for the memory, the engineers was so good back then

That's some funky battery arrangement inside the computer. Making the best of the available space, I guess.

I got one of these from my dad, and when i saw the LCD screen (same deterioration on the screen) i knew it wasn’t going to work. But i kept it anyways for moments like this.

Where are you buying LR44 batteries that they're $5 a piece? I bought a 40 pack on Amazon for $8 and they've worked just fine in my cameras.

I buy a big huge blister of LR44 Varta Industrial cells there's like 20 or 40 on there once every few years, and magically they do get used up SOMEHOW. The whole blister goes for like $3. These are not expensive cells.

3:03 Those are only expensive when you buy them at local stores at their ripoff retail prices. When you buy them in bulk online, they are quite cheap.

I am wondering, is the capital letter O and the double-quote showing something wrong with the character ROM, or just a choice made to distinguish characters? Good stuff!

I have a pc 2 (I learned BASIC with it.) I had the printer plotter/ cassette interface too.

Very cool, I used to use a Tandy 101 in the squad car to type up reports in the car. Our small agency didn't have a computer to it's name so I used my own, at home I had a C=128 at the time, eventually went to a 386. Had a SX-64 luggable that I used to haul up to the PD for some of the stuff I wanted on the computer, ah but that little Tandy, wish I had kept one, had 3 at one time but ended up selling all 3 to one fellow, I listed one for sale and when the dude saw 3 he made me an offer. I could not refuse. Wouldn't mind having one again though.

You can get a set of LR44 batteries from the Doller Tree. I had to get some for a micrometer

It's a mini Model 100. :) That's pretty cool. Nice repair and great video.

Such a nice little computer. Nice job 👍🏻

Hold up... $20 for 4x LR44 batteries? That seems high... Dollar Tree usually has them, and my local TSC stocks a coin cell multi pack for about $13 that has a bunch of LR44, CR2016, and CR2032 cells in it.

Nice work! You made me chuckle with "HI"... the 21st century version of "HELLO WORLD!" 🙂

Mine was a Casio. A bit horrible because it was 1K or something and I was leaving my ZX-Spectrum adventure. The quality was great except the battery change/life and the resets.

It was the clone of the Sharp PC-1211, a nice piece, rare in fonction today. Basic OS and options like printer, recorder, etc....

I can imagine a bunch of kids just learned about the wonders of polarizers and LCDs from this video! Great job!

Breaking Taps did a super vid about Z conductive tape.

You may be right but those old basic interpreters would also truncate the text of the token. i.e. it may be the line editor did it to you. Check the rounding with a calculation. PRINT 5/7 for example.

If you ever get a good schematic you can read, check the pinout of that header, because technology of the time is likely to have sent that data through that header as a mono waveform in the same format as any 1/8" mono jack would have otherwise, which could mean the possibility of wiring up a simple female headphone jack to TRS-80 through its header, just without the plug, and being able to "send data" to this over anything that plays audio. There's even the chance you can take the audio clip from this video out, and feed it back into the port once working to reaccess the actual code you wrote for the video.

So if the contrast is not exactly right one thing I might recommend is just soldering on a resistor instead of the potentiometer.

All I can say is thanx for fixing my model 1 trs80 pocket pc

I'm so glad I found this channel, but I'm not sure why..

I had a Casio one of these and wrote a program to work out compounding interest. I know there's an equation for that, but it would iterate to the end, and after dialling it in I could go in armed. Carried it around for years until it was stolen from my car.

this rubber zebra connection was always mystery for me as a kid

My tinnitus said "hi, long time no see".

Why do I always forget about my 3d printer when I need to heat things like this? I always just go for the heat gun, but this seems far safer, considering it's temp controlled.

The old LCD will release easily with heat. You need to get the temp about 100C and let it 'cook' for 5-10 minutes. I have done this 5-6 times now, works every time.

If I recall, those are rechargeable batteries. They are 1.25vdc nominal each cell, not 1.55v each.

I thought I remembered this thing to have a 3.5mm plug for Audio in/out? You can save the audio to Audacity and simply play it back. R u sure the speaker does not double as a Mike? You can upload the recorded file for your Patreons

Ah, but the serial interface standard uses negative voltages too, that's probably what they need that for

I had one in high school. Also used it to pass physics in college. Just programmed needed formulae in as basic comments.

Maybe the adapter to the tape recorder "takes over" the signal going normally to the speakers.

The machine is OEM from SHARP corporation, PC-1210 or PC 1211 depends on its memory size.

14:02 so why does the letter O look like there is a fault at the top right?