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I don't have a pinout of the cable, but I do have a schematic of the cable adapter. With this, you should be able to use the pinout of the TRS-80 to come up with a pinout for the printer.

I wonder what internal registers it has.

Swap video boards with the working one to see if the CRT is any good? Is the CRT heater glowing? Is there any blue glow in the neck of the CRT? If there is a blue glow then it's gassed and you need a new tube. Be cautious of high voltages!

I'm in the processes of restoring a TRS-80 model 4 gate array and have located one of the problems causing the system to hang at startup and only show garbage on the screen. The FDC timing chips is dead and sends a hold signal to the CPU which was also bad along with the ROM chips. I can make...

I've gotten the USB host adapter for the arduino in the mail and got it all working. I had to do some more tinkering with the code to make the DT80 happy with input. One of the things I had to change was the key mapping. It's completely different! Afterwards though, I got everything except...

I think this is the same kind of paper. https://www.bladegood.fun/product/Silverno-890-2b-060-Recording-Metalized-Paper-pack-Of-5_e6gpnprtsmouotr.html

WOW. Talk about an improvement! Still got some blank spots though. I gotta figure that out.

Yeah, it's supposed to have some random stuff I had on the screen + 'HELLO WORLD' Here's some more pictures I did after fixing a few other small problems and adjusting the head using the "ABCABCABC" method. It seems to not make the very best contact with the wheel and the fingers might be...

It makes no since to me based on what I know about the pinout, the pinout posted above, and the way the printer beeps out with the meter, but it's working somewhat now. Somehow...

I finally got some time + energy at the same time today to play with this some more. After sitting down with the TRS-80 pin diagrams, some tea, and a soldering iron, I tried another new configuration to no avail. This configure made sense on paper and ohm meter probe, but the TRS-80 would fail...

Well, looks like I will be partly or completely reverse engineering the circuit board of the printer to get a schematic and thus a pinout.

So what you're saying is that I had it right before swapping pairs and that there is something else wrong?

Well, I thought I was on to something with that, but I just got done swapping every pair and after checking for shorts and continuity the TRS-80 only shows garbage if the cable is connected even with the printer disconnected.

I've made the adapter cable and have been testing + debugging this thing these past few weeks on and off. Mostly on weekends when I have the time. Today in particular I've been working on it a lot. I've pulled and tested nearly every chip on the board, which is something I really don't like...

I got the emulator to work (without it's USB host adapter, I disabled that code for now until one arrives in the mail). Here's what I had to do. First off, after some probing, I had accidentally grounded the signal line in my connector during assembly so I wasn't getting any data through. After...

ah, thank you! I should have guessed to look there since I had been working with Al on preserving documentation of this stuff. I did some more tests and I think my HD-6402 is bad. It doesn't appear to be sending any data on it's output even though it's getting a clock signal and RD/WR signals...

The DT80 and VT100 keyboard circuits are so close in design that I would be surprised if the VT100 keyboard didn't work on the DT80, though not surprised at all if the DT80's keyboard didn't work on the VT100. Both of their send/receive circuits are different, but perform the same function at...

A recent update. Someone reached out to me on HAD mailed me ALL of the schematics to the DT80! This inspired me to try and get the original firmware working again rather than just re-writing my own which I had gotten pretty far on. After about an hour of video recording clips and minor trouble...

Ahhhh. I figured the centronics connection was wrong. As stated, it's going from 40 pins to 50 pins. Eudimorphodon is correct in the operation as far as I can tell after taking it apart and looking at the circuit. The first board shown in that article looks very similar to the one in the...

I understand it's for a VT-100, but based on the VT-100's service manual, and the way the circuit looks on the DT80, there is a chance they are electrically compatible. It's also the cheapest VT-100 keyboard I have ever seen, and it looks to use the same or similar keys to the early TRS-80's...