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by Teknoman117 91 days ago
The unfortunate reality of building these home-brew CPUs is that almost all of the "medium integration" ICs are long out of production - things like the 74181 ALU slice, carry lookahead adders, 16-way register files, etc.

Makes doing things larger than 8/16 bit computers very complicated and usually very slow :(
1 comments
wwarren 91 days ago
YES, a modern version of the 74181 is equivalent to about 12-20 chips in the LS or HC series. It would be so useful. Someone should do a tiny tapeout!
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Lerc 91 days ago
The Gigatron uses 5 chips for a 4bit ALU.

It's one of the test layouts that I put in this perfboard layout program that I ened up making because trying to figure out wiring on both sides at once in my head melted my brain.

https://fingswotidun.com/PerfBoard/ (Try the 4-bit ALU example)

Of course I haven't yet verified it works because of getting sidetracked by the editor, https://xkcd.com/974/

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