A Tiny Terminal For Your Serial Access Needs

Some pieces of computing equipment have faded away without a trace, for example a modem is not a device that detains many hackers as they strive for that perfect emulation of a venerable Hayes on an Arduino. But there are some other devices that continue to hold a fascination, even years after they departed from the professional arena. A great example is the serial terminal. Once to be found on many a desk as it provided a way into a minicomputer, it has long ago been supplanted by terminal emulators or simply other portals into computing services such as the web. But in our community there are still plenty of serial terminals to be found, for example [RedHog]’s little emulated VT220 on an ESP8266 platform.

If you were hoping for a full-green screen and keyboard to plug into a hefty D-connector serial port then you’ll be a bit disappointed, as with a tiny screen and only a few buttons on a dev board or an Arduboy it’s not going to allow any 1337 vi mastery even with its on-screen keyboard. Take a look, we’ve placed a video below the  break. But despite all that it shows promise, with ability to use either the logic-level serial port or the USB serial interface. We can see that it might find a use as a serial display though, but it would fascinate us to see what could be done were it to use the 8266’s on-board WiFi in some form. If you’d like to experiment you can do so with the code on GitHub.

This isn’t the first such terminal we’ve seen here before of course, some of them have been extremely practical, while others we just want to own because they’re cool.

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DIY VT220 Keyboard

There’s always been interest in the computers of old, and people love collecting and restoring them. When [peterbjornx] got his hands on a DEC VT220 video terminal, it was in good shape – it needed a bit of cleaning, but it also needed a keyboard. [Peter] couldn’t afford to buy the keyboard, but the service manual for it was available, so he decided to convert a modern keyboard to work with his new terminal. (Editor’s note: Link rot. Try the Internet Archive’s Wayback Machine link instead.)

The original keyboard for the VT220 is the LK201. This keyboard communicates with the terminal using 8-N-1 (eight data bits, no parity, one stop bit) over RS232 at 4800 baud. This meant that it would be pretty simple to implement this on microcontroller in order to communicate with the terminal. [Peter] chose the Arduino Nano. However, the LK200 was more than just a keyboard for communicating with the terminal, it also housed a speaker and LEDs which the terminal used to communicate with the user. Rather than put these into the adapter unit, [Peter] decided to put these into the keyboard – a few holes and a bit of wiring, and they were in.

[Peter]’s write-up includes a description of some of the issues he encountered as well as a picture of the keyboard. He’s put the schematic online and the code up on GitHub. In case you were wondering, he used Vim on the VT220 to write his article. You could also use a Raspberry Pi to help out your dumb terminal, or just hook the terminal directly to your Linux box and go from there.

By The Glow Of The CRT

If you are a certain age, you probably remember writing software (or playing Adventure) bathed in an amber or green light from an old CRT terminal. If you are even older, you might have found it way better than punching cards, but that’s another story. [Tobi] wanted to relive those days (well, sounds like he is too young to have lived them to start with) so he hooked up a VT220 terminal to his Linux box.

This isn’t that surprising. Linux’s forefather, Unix, expected these kind of terminals (or a hard copy TeleType) and all the trappings for working with a glass terminal are still in there. You do have to deal with a few configuration items that [Tobi] works through.

In fact, it appears that he wrote his blog post using vi on that very VT220 using a text-based Web browser to research the links. He has a lot of resources for connecting a terminal of any sort (or even a terminal emulator) to a Linux computer.

There’s been a lot of interest in old terminals lately. You see a lot of old VT100s lying around. I personally have an ADDS Regent 100 that occasionally connects to several of my computers. You can see it in the video below.

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How To Create TrueType From An Image


[Viacheslav] wanted his virtual terminal to have the look of a DEC VT220. He was unable to find a font set that looked just right so he set out to make his own TrueType font. He managed to find a sample image of the glyphs that the VT220 used as fonts. Using a collection of free software he sliced the image into 256 different parts, resized and converted to one-bit index images, and converted these to vector graphics. This was accomplished with a bit of python, an image tracing program, and font editor called FontForge.

Take some time to dabble with these font tools. With an adequate sample you should be able to reproduce any font set. We won’t achieve anything as sophisticated as the font printed with bacteria, but this will be a start in the right direction.