[John Whittington] failed to win a bid for an old VT-220 serial terminal on eBay, so he decided to make his own version and improve it along the way. The result is the Whitterm-220 (or WT-220) which has at its core a Raspberry Pi and is therefore capable of more than just acting as a ‘dumb’ serial terminal.
The enclosure is made from stacked panels of laser-cut plywood with an acrylic plate on the back for labels and connectors, where [John] worked paint into the label engravings before peeling off the acrylic’s protective film. By applying paint after laser-engraving but before peeling off the film, it acts as a fill and really makes the text pop.
Near the front, one layer of clear acrylic among the plywood layers acts as a light guide and serves as a power indicator, also doing double duty as TX/RX activity lights. When power is on, that layer glows, serving as an attractive indicator that doesn’t interfere with looking at the screen. When data is sent or received, a simple buffer circuit tied to the serial lines lights up LEDs to show TX or RX activity, with the ability to enable or disable this functionality by toggling a GPIO pin. A video overview is embedded below, where you can see the unit in action.
When it was released, the Beckman Model 421 CRT controller represented the latest and greatest in liquid chromatography technology. Its 12 inch screen would allow the operator to view critical information such as flow rate and concentration, and its integrated keyboard simplified system control. It made liquid chromatography faster and easier, allowing lab technicians to focus on analysis rather than the complexities of operating the equipment.
[Igor] explains that the Model 412 is essentially just a dumb terminal with no internal logic, so in theory it should have been possible to just hang the thing on a serial port and be done with it. But unfortunately the display drive board was dead, so a full rebuild was in order. This meant that there’s little left of the original device other than the keyboard and the case itself, but since it isn’t exactly a “vintage computer” in the traditional sense, we think the purists will allow it.
For the display, [Igor] used an LCD he salvaged from an old digital picture frame. It was the right size to fit the opening, and thanks to an unpopulated VGA header on the board, wasn’t too difficult to get connected to the Pi with an HDMI adapter. He also added a hardware VGA scanline generator board so that no matter what the Pi shows it will have that classic old-school look; a fantastic detail we don’t usually see on builds like this.
The keyboard on the Model 412 was more of a control panel than a traditional input device, so not only does it have keycaps which say things like “FLOW RATE” and “WRITE TAPE”, but it has a fairly weird layout. After reverse engineering the somewhat unusual key matrix, he spun up a custom firmware for the Arduino Pro Micro using QMK which would let him use the board on the Pi as a standard USB input device. But rather than replace the keys, [Igor] created a little cheat-sheet overlay that he could put over the board to see what keys translate to which letters. It’s awkward for sure, but we really appreciate that he preserved the unique nature and look of the Model 412.
A Linux terminal has a lot more features than the TeleType of yore. On a TeleType, text spews out and scrolls up and is gone forever. A real terminal can use escape characters to do navigate around and emulate most of what you like about GUIs. However, doing this at the lowest level is a chore and limits portability. Luckily, all the hard work has already been done.
First, there’s a large database of terminal capabilities available for you to use: terminfo. And in addition, there’s a high-level library called curses or ncurses that simplifies writing programs to control the terminal display. Digging deep into every nook and cranny of ncurses could take years. Instead, I’m going to talk about using a program that comes with ncurses to control the terminal, called tput. Using these two commands, you can figure out what kind of terminal you’re dealing with, and then manipulate it nearly to your heart’s content. Let’s get started!
If you haven’t kept up with the world of e-ink displays, here’s some good news: they are pretty cheap now. For as little as $15 you can get a small e-ink display that has good enough performance and contrast to actually do something useful. There’s only one problem: figuring out how to drive them in your project.
Tired of seeing nothing but wiring diagrams and sample code when it came to actually putting these e-ink modules to use, [Jouko Strömmer] decided to try his hand at creating a turn-key application for these gorgeous little displays. The result is PaperTTY, a Python program that allows the user to open up a fully functional Linux virtual terminal on an e-ink display.
Of course, there are some caveats. For one, this all assumes you’re using a Waveshare display (specifically their 2.13 inch HAT) connected to a Raspberry Pi over SPI. Not to say that’s the only hardware combination that will work, but it’s the only one that [Jouko] has done any testing on at this point. If you want to try to shake things up in terms of hardware, you might need to get your hands dirty.
The advantage of being able to open a Linux VT on one of these e-ink displays is pretty simple: you can run basically any piece of software you want on it. Rather than having to come up with software that specifically features support for the display, you can just use (or write) standard Linux console programs. [Jouko] mentions a number of popular programs such as vim and irssi, but you could just as easily write a Bash script to dump whatever data you like to the screen.
In the video after the break [Jouko] shows PaperTTY in action for the doubters who think these sorts of displays are no good for interactive use. The display is very crisp and readable, with no signs of flickering. Overall he says the experience is not unlike using a slow SSH connection. It might not be how we’d like to use a computer full time, but we can definitely see the potential.
Back in the 70s when I started getting interested in electronics, tons of magazines catered to the hobbyist market. Popular Electronics was my favorite, and I think I remember the advertisements more than anything, probably because they outnumbered articles by a large margin. Looking back, it seemed like a lot of ad space was sold to companies hawking the tools and materials needed for wire wrapping, which was very popular for prototyping in the days before solderless breadboards were readily available. I remember beauty shots of neat rows of small, gold posts, with stripped wires wrapped evenly around them.
To the budding hobbyist, wire wrapping looked like the skill to have. With a huge selection of posts, terminals, and sockets for ICs and discrete components, as well as a wide range of manual and powered wrapping tools, it seemed like you could build anything with wire wrapping. But fast forward just a decade or so, and wire wrapping seemed to drop out of favor. And today — well, does anyone even wire wrap anymore?
Many of us could use a general-purpose portable workstation, something small enough to pocket but still be ready for a quick troubleshooting session. Terminal apps on a smartphone will usually do the job fine, but they lack the panache of this pocketable pop-top Raspberry Pi workstation.
It doesn’t appear that [Michael Horne] has a specific mission in mind for his tiny Linux machine, but that’s OK — we respect art for art’s sake. The star of the show is the case itself, a unit intended for dashboard use with a mobile DVD player or backup camera. The screen is a 4.3″ TFT with a relatively low-resolution, so [Michael] wasn’t expecting too much from it. And he faced some challenges, like dealing with the different voltage needs for the display and the Raspberry Pi Zero W he intended to stuff into the base. Luckily, the display regulates the 12-volt supply internally to 3.3-volts, so he just tapped into the 3.3-volt pin on the Pi and powered everything from a USB charger. The display also has some smarts built in, blanking until composite video is applied, which caused a bit of confusion at first. A few case mods to bring connectors out, a wireless keyboard, and he had a nice little machine for whatever.
We’re not sure which is more fun – putting together a little RC truck with parts laying around on your workbench, or driving it around through a Linux terminal. We’ll take the easy road and say they’re both equally fun. [technodict] had some spare time on his hands and decided to build such a truck.
He started off with a great little chassis that can act as the base for many projects. Powering the four motors is a cheap little dual H bridge motor driver and a couple rechargeable batteries. But the neatest part of this build is that it’s controlled using a little bit of python and driven directly from a terminal, made possible by the Raspberry Pi Zero of course.
With Raspberry Pi Zero now having built in WiFi and Bluetooth – we should see a lot more projects popping up with one at its heart. Be sure to visit [technodict’s] blog for full source and details. And let us know how you could use that little chassis for your next mobile project!