Day: November 21, 2023

Illustrated Kristina with an IBM Model M keyboard floating between her hands.

Keebin’ With Kristina: The One With The Duplex Typewriter

November 21, 2023 by 10 Comments

The Coleco Adam? A not-so-great home computer that likely contributed to the downfall of the company. The keyboard, however, is a different story, and worth repurposing.

[Nick Bild] has created a USB adapter that uses a Teensy 4.1 and an RJ-12 breakout board. Now this wasn’t just a simple matrix to decode. No, the fine folks at Coleco rolled their own communications protocol called AdamNet.

The keyboard uses an RJ-12 connector and a single data line to communicate over a 62.5 kbit/s, half-duplex serial bus. Inside the keyboard is a Motorola 6801 that caches the key presses and sends them to the computer. So the BOM is limited to what you see above — an RJ-12 breakout and a Teensy 4.1. It’s great to see old keyboards come alive again, especially one with such cool sci-fi keycaps. Want to hear it clack? Of course you do.

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LiPo Replacement Keeps Portable Scanner In The Action

November 21, 2023 by 8 Comments

If there’s anything people hate more than being locked into a printer manufacturer’s replacement cartridges, it’s proprietary batteries. Cordless power tools are the obvious example in this space, but there are other devices that insist on crappy battery packs that are expensive to replace when they eventually die.

One such device is the Uniden Bearcat BC296D portable scanner that [Robert Guildig] found for a song at a thrift store, which he recently gave a custom LiPo battery upgrade. It came equipped with a nickel-cadmium battery pack, which even under the best of circumstances has a very limited battery life. Using regular AA batteries wasn’t an option, but luckily the space vacated by the OEM battery pack left a lot of room for mods. Those include a small module with BMS functions and a DC-DC converter, a 2,400 mAh 4.2 V LiPo pillow pack, and a new barrel connector for charging. With the BMS set for six volts and connected right to the old battery pack socket, the scanner can now run for seven hours on a one-hour charge. As a bonus, the LiPo pack should last a few times longer than the NiCd packs, and be pretty cheap to replace when it finally goes too. There’s a video after the hop with all the details.

If you’re looking at a similar battery replacement project, you might want to check out [Arya]’s guide to everything you need to know about lithium-ion circuitry.

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Zork Zcode Interpreters Appear Out Of Nowhere

November 21, 2023 by 27 Comments

Some of our readers may know about Zork (and 1, 2, 3), the 1977 text adventure originally written for the PDP-10. The game has been public domain for a while now, but recently, the interpreters for several classic 1980s machines have also appeared on the internet.

What’s the difference? Zork is not a PDP-10 executable, it’s actually a virtual machine executable, which is in turn run by an interpreter written for the PDP-10. For example, Java compiles to Java bytecode, which runs on the Java virtual machine (but not directly on any CPU). In the same way, Zork was compiled to “Z-machine” program files, called ZIP (which was of course used in 1990 by the much more well known PKZIP). To date, the compiler, “Zilch” has not been released, but the language specification and ZIP specifications have, which has led some people to write custom ZIP compilers, though with a different input language.

For more on the VM, check out Maya’s Zork retrospective. (And dig the featured art. Subtle!)

Of course, that’s not the only type of interpreter. Some programming languages are interpreted directly from source, like this BASIC hidden in the ESP32’s ROM.