Linux Fu: The Old School Terminal

August 23, 2023 by 40 Comments

Maybe you have a vintage old-school computer. Maybe you have a replica. Maybe you just want to run SIMH and relive the glory days of CP/M or VMS. The problem is, it looks kind of silly to have CP/M running in your beautiful X11 terminal window full of 3D animations, opacity effects, and special fonts. You could buy an old CRT monitor. That would be cool, too, because on a modern screen, you don’t get scan lines and all the crummy artifacts that go along with an electron beam and phosphor display device. Or you can grab retro-cool-term.

Star Trek on CP/M

Even if you don’t have an old computer, the program will work fine to simply run your shell for everyday use. Confound the youngsters when they see your terminal with scan lines and CRT jitter updating the latest packages.

What Is It?

If you want a shell in a GUI, you used to use xterm, although most people use something more modern. I use Konsole, but some like RXVT or whatever terminal your distro favors. Cool-retro-term is just a replacement for this. By default, it only opens a shell prompt.

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Selectric Typewriter Goes From Trash Can To Linux Terminal

July 25, 2023 by 19 Comments

If there’s only lesson to be learned from [alnwlsn]’s conversion of an IBM Selectric typewriter into a serial terminal for Linux, it’s that we’ve been hanging around the wrong garbage cans. Because that’s where he found the donor machine for this project, and it wasn’t even the first one he’s come across in the trash. The best we’ve ever done is a nasty old microwave.

For being a dumpster find, the Selectric II was actually in pretty decent shape. The first couple of minutes of the video after the break show not only the minimal repairs needed to get the typewriter back on its feet, but also a whirlwind tour of the remarkably complex mechanisms that turn keypresses into characters on the page. As it turns out, knowing how the mechanical linkages work is the secret behind converting the Selectric into a teletype, entirely within the original enclosure and with as few modifications to the existing mechanism as possible.

Keypresses are mimicked with a mere thirteen solenoids — six for the “latch interposers” that interface with the famous whiffletree mechanism that converts binary input to a specific character on the typeball, and six more that control thinks like the cycle bail and control keys. The thirteenth solenoid controls an added bell, because every good teletype needs a bell. For sensing the keypresses — this is to be a duplex terminal, after all — [alnwlsn] pulled a page from the Soviet Cold War fieldcraft manual and used opto-interrupters to monitor the positions of the latch interposers as keys are pressed, plus more for the control keys.

The electronics are pretty straightforward — a bunch of MOSFETs to drive the solenoids, plus an AVR microcontroller. The terminal speaks RS-232, as one would expect, and within the limitations of keyboard and character set differences over the 50-odd years since the Selectric was introduced, it works fantastic as a Linux terminal. The back half of the video is loaded with demos, some of which aptly demonstrate why a lot of Unix commands look the way they do, but also some neat hybrid stuff, like a ChatGPT client.

Hats off to [alnwlsn] for tackling a difficult project while maintaining the integrity of the original hardware.

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A Thoroughly Modern Serial Terminal

March 1, 2023 by 16 Comments

The humble desktop serial terminal may have long disappeared from the world of corporate IT, but there are still plenty of moments when professionals and enthusiasts alike need to hook up to a serial port. Many of us use a serial port on our laptops or other mobile devices, but [Neil Crawforth] has gone one better than that with the VT2040. It’s an old-style serial terminal in a super-handy portable format, and as one might guess from the name, it has an RP2040 microcontroller at its heart.

Attached to the chip is a rather nice keyboard, and an ILI9488 480×320 LCD display. The software is modular, providing a handy set of re-usable libraries for the different functions including a PIO-based serial port. His main application seems to be talking to an ESP8266, but we’re guessing with a MAX232 or other level shifter chip it could drive a more traditional port. Everything can be found in the project’s GitHub repository, allowing anyone to join the fun.

As long-time readers will know, we’ve been partial to a few serial terminals in the past. Particularly beloved is this extremely retro model with vintage dot matrix LEDs.

A picture showing acupuncture needles wedged into the inside of the payment terminal

Aaron Christophel Brings DOOM To Payment Terminal

March 1, 2023 by 9 Comments

Payment terminals might feel intimidating — they’re generally manufactured with security in mind, with all manner of anti-tamper protections in place to prevent you from poking around in the hardware too much. But [Aaron Christophel] thinks that level of security isn’t aren’t always in practice however, and on his journey towards repurposing devices of all kinds, has stumbled upon just the terminal that will give up its secrets easily. The device in question is Sumup Solo terminal, a small handheld with a battery, LTE connection and a payment card slot – helping you accept card payments even if you’re on the go.

Now, this terminal has security features like the anti-tamper shield over the crucial parts of the device, leading to payment processing-related keys being erased when lifted. However, acupuncture needles, a tool firmly in [Aaron]’s arsenal, helped him reach two UART testpoints that were meant to be located under that shield, and they turned out to be all that a hacker needed to access the Linux system powering this terminal. Not just that, but the UART drops you right into the root shell, which [Aaron] dutifully explored — and after some cross–compilation and Linux tinkering, he got the terminal to, naturally, run Doom.

The video shows you even more, including the responsible disclosure process that he went through with Sumup, resulting in some patches and, we hope, even hardware improvements down the line. Now, the payment processing keys aren’t accessible from the Linux environment — however, [Aaron] notes that this doesn’t exclude attacks like changing the amount of money displayed while the customer is using such a terminal to pay.

If you’d like to take a closer look at some of the hardware tricks used in these secure devices, we did a teardown on one back in 2019 that should prove interesting.

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side by side, showing hardware experiments with capacitor gating through FETs, an initial revision of the modchip board with some fixes, and a newer, final, clean revision.

A Modchip To Root Starlink User Terminals Through Voltage Glitching

November 28, 2022 by 36 Comments

A modchip is a small PCB that mounts directly on a larger board, tapping into points on that board to make it do something it wasn’t meant to do. We’ve typically seen modchips used with gaming consoles of yore, bypassing DRM protections in a way that a software hacks couldn’t quite do. As software complexity and therefore attack surface increased on newer consoles, software hacks have taken the stage. However, on more integrated pieces of hardware, we’ll still want to return to the old methods – and that’s what this modchip-based hack of a Starlink terminal brings us.

[Lennert Wouters]’ team has been poking and prodding at the Starlink User Terminal, trying to get root access, and needed to bypass the ARM Trusted Firmware boot-time integrity checks. The terminal’s PCB is satellite-dish-sized, so things like laser fault injection are hard to set up – hence, they went the voltage injection route. Much poking and prodding later, they developed a way to reliably glitch the CPU into verifying a faulty firmware, and got to a root shell – the journey described in a BlackHat talk embedded below. Continue reading “A Modchip To Root Starlink User Terminals Through Voltage Glitching” →

A terminal window with a search for "Guineau Pig Olympics" is inset on a photo of an ortholinear keyboard attached by a yellow USB cable to a 70s aluminum and plastic Super 8 film editor/viewer. The device has a large screen on the right hand side, a silver grate on the left, and a tray at the bottom for slotting in film.

Super 8 Film Editor Reborn As A YouTube Terminal

October 30, 2022 by 14 Comments

We love hacks that give new life to old gadgets, and [edwardianpug]’s YouTube Terminal certainly fits the bill by putting new hardware inside a Super 8 film editor.

[edwardianpug] could have relegated this classy-looking piece of A/V history to a shelf for display, but instead she decided to refresh its components so it could display any YouTube video instead of just one strip of film at a time. The Boost-Box keeps the retrofuturistic theme going by using the terminal to search for and play videos via Ytfzf.

The original screen has been replaced by an 800×600 LCD, and the yellow USB cord gives a nice splash of color to connect the ortholinear keyboard to the device. Lest you think that this “ruined” a working piece of retro-tech, [edwardianpug] says that 20 minutes would get this device back to watching old movies.

Are you looking for more modern and retro mashups? Check out these Dice Towers Built In Beautiful Retro Cases, a Vacuum Tube and Microcontroller Ham Transmitter, or this Cyberdeck in a Retro Speaker.

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A widescreen slate-style cyberdeck with a small keyboard sits in front of a cassette deck stereo. Headphones sit to the left of the deck and an old Casio calculator watch is to the right.

2022 Cyberdeck Contest: QAZ Personal Terminal

October 22, 2022 by 9 Comments

The slabtop form factor has had a resurgence in the cyberdeck community, and [Greg Leo] has designed the QAZ Personal Terminal to be about as small as a slabtop could be while still having full-sized keys.

Since the device is using a 35% QAZ keyboard as its primary input device, [Leo] has helpfully given a quick overview of how text is input in the video below. Coupled with that surprisingly popular 4:1 LCD screen we’ve seen elsewhere, this cyberdeck looks like a modern interpretation of a TRS-80 Model 100. The Banana Pi powering the QAZ Personal Terminal is running Debian with spectrwm, a tiling window manager making arranging windows a breeze with either a mouse or keyboard. The integrated mouse layer on the keyboard means you don’t need a separate mouse at all if you don’t want to spoil the 1980s mobile chic.

[Leo] has another video all about doing calculus on this cyberdeck with the math shortcuts integrated into the keyboard. Fractions, exponents, and common Greek letters are demonstrated. We can see this being a really great note-taking device for engineering and math courses if you wanted something more portable than a laptop.

It’s hard to get very far hacking without a little math. For more math-focused input devices, check out the Mathboard or the MCM/70.

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