A CIA In 74HCT

If you owned a classic Commodore home computer you might not have known it at the time, but it would have contained a versatile integrated circuit called the MOS6526. This so-called CIA chip, for Complex Interface Adaptor, contained parallel and serial ports, timers, and a time-of-day counter. Like so many similar pieces of classic silicon it’s long out of production, so [Daniel Molina] decided to replicate a modern version of it on a PCB using 74HGT CMOS logic.

The result will be a stack of boards board that appear to be about the size of a 3.5″ floppy disk covered in surface-mount 74 chips, and connected to the CIA socket of the Commodore by a ribbon cable. The base board is the only one completed so far and contains the data direction registers and parallel ports, but the succeding boards will each carry one of the chip’s other functions.

It seems rather odd to use so much silicon to recreate a single chip, but the point is not of course to provide a practical CIA replacement. Instead it’s instructive, it shows us how these interfaces work as well as just how much circuitry is crammed into the chip. It’s no surprise that it’s inspired by the C74 Project, a TTL 6502 processor that we featured last year.

Hackaday Links: August 5, 2018

Here’s something of historical interest. The daughter of Terry Holdt, project manager for the 6502, cleaned out a garage and found shelves full of MOS Technology binders, test results, notes, instructions for processes, letters to customers, and datasheets full of errata. Some of these documents have been posted on Twitter, and efforts are underway to collect, scan, upload, and preserve them. In the distance, a man in a fabulous suit is screaming, ‘donate them to the Internet Archive’.

This is a link to Defcad, the repository of 3D printable files for weapons. Under an agreement with the US Department of State, Defcad was set to go online on August 1st. This caused much handwringing in the tech journalist thoughtspace, with reporters calling to end the first amendment because they don’t like the second. Alyssa Milano chimed in. Defcad was ordered shut down by a federal judge in the western district of Washington before going live.

As you may well be aware, Printrbot ceased operations last month. It’s sad to see them go, but they made some acceptable machines and were really pushing the boundaries of what was possible with their infinite build volume prototype printer. But what about all those existing printrbots in the wild, you might ask. Well, good news for anyone who hasn’t changed their hotend over to an E3D yet: Ubis is going to be selling hotends. Get ’em while they’re hot (or not, I don’t know how this pun works).

File this one into the ‘awesome government auctions’ category. The city of Longmont, Colorado decommissioned their tornado sirens last year because they ‘self-activated’ and malfunctioned. These sirens were put up for auction, with a winning bid of $526. Someone bought the most annoying thing imaginable for just over five bills. The world of government auctions is amazing.