Category Archives: logic gates

Relay Computing

Recently, [Manuel] did a post on making logic gates out of anything. He mentioned a site about relay logic. While it is true that you can build logic gates using switch logic (that is, two switches in series are an AND gate and two in parallel are an OR gate), it isn’t the only way. If you are wiring a large circuit, there’s some benefit to having regular modules. A lot of computers based on discrete switching elements worked this way: you had a PCB that contained some number of a basic gate (say, a two input NAND gate) and …read more

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Posted in Engineering, Hackaday Columns, logic, logic gates, misc hacks, mux, relay, relay computer, relays | Leave a comment

Yes, You Can Reverse Engineer this 74181

[Ken Shirriff] is the gift that keeps on giving this new year. His latest is a reverse engineering of the 74181 Algorithmic Logic Unit (ALU). The great news is that the die image and complexity are both optimized for you to succeed at doing your own reverse engineering.

We have most recently seen [Ken] at work explaining his decapping and reverse engineering process at the Hackaday SuperCon followed soon after by his work on the 8008. That chip is crazy with complexity and a die-ogling noob (like several of us on the Hackaday crew) stands no chance of doing more …read more

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Posted in ALU, classic hacks, die, die photo, ken shirriff, logic, logic gates, reverse engineering, silicon | Leave a comment