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VT420 - Spoils of War

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         	                 Blaze It!
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Try

Working $DAYJOB, I was ordered to clean out an old server room. It was no ordinary server room, it was the room with treasure; a VT420 build on 19 August 1991. The first time I saw it, a few years earlier, I hoped I was the one that would save it from this awful server room and give it a new home, a greater purpose, a better life, and in general the love it deserves. And thus I tried.

At First I used an ESP32, just to keep the terminal more terminally as in "minimal compute" actions. I started, got close but ultimatly failed. Writing my own ssh console client on a microcontroller is currently still to hard form me, even writing a simple telnet console was a daring task. In this area I still have much to learn, but one day, some day I'll get to it. I'll have to, I still have 3 ESP32 Modules lying around.

Catch

To keep this project moving, I needed an upgrade. Luckily for me I'm an impulsive buyer, so I also have 2 Onion Omega2 Linux Compute Modules. Which I actually would not recommend. It seems impossible to turn off AP mode, but you can hide the SSID, and the pins are spaced at 2mm not the 2.54mm all my breadboards and plates are in. It did help me get on with the resurrection as these embedded linux devices are more on my level. It gives you a linux kernel, some packages, and a nice working dev environement where you just type "make" after being in "make menuconfig" for an hour and get a working binary ready to flash, or in my case an evening or 2 mixing and matching kernel configuration, packages,handcrafted scripts, and some additions/removals from the default file-tree. Now that I'm writting this I'm coming to the realisation I currently don't have a backup of my work. I probably should do something about that.

Hardware-wise I still needed a MAX232 Chip to translate voltages from TLL to RS-232, a broken out DB25 connecter, and a 230V-3.3V Transfo. All these things are rather cheap, and now I have several of them. What's the point in buying parts for €2 and paying €5 for shipping, right?

Unlike all the other components the Omega2 did not pin-out on my prototypeboard, so it was "dead bugged" and glued on.

Finally

With the Omega2 communicating with the terminal, it was time to configure the host machine. The best way, I assumed, was to create a new user with it's own login shell, as there are some "bugs" in Linux regarding the VT420 terminal. I wrote a Go application that parses a JSON and builds a menu using ncurses. I would link to the Git repo, but am again confronted with the fact that there is no git or a backup. I probably should do something about that. Before packing the prototype board into a nice pink plastic case, I changed the DB25 connecter with a proprietary Modified Modular Jack (MMJ) connector, as it fits better, and gives me more wiggleroom.

The keyboard needed a tiny repair as wel, the 'v' wasn't always registerd. Which made it very hard to play Hangman, and do other tasks. A small drop of hot glue was enough to make the stem of the keycap a fraction lager so it would get to the switch.

What is working

What is not working

The terminal is now setup in a room we call "the workshop" and is mainly used to browse gemini, read mails, and play games.

If you can think of any neat features that I shoud add to my Terminal, please let me know.

Pictures

VT420 menu

VT420 running amfora

Side A with the dead bugged Onion

Side A again

Side B, a transfo and some pins

World's Smallest "Mainframe"

custom flash cable Data lines to FAT USB, powerlines to plug.

Links

vt420 Manual.pdf

Onion Omega2

Issues when conencting a VT420 to a Linux box

Amfora