Sounds nice. I just have a little problem: hasn't the 74181 been discontinued? I never found a modern equivalent —unlike other components such as multiplexers,

Sounds nice. I just have a little problem: hasn't the 74181 been discontinued? I never found a modern equivalent —unlike other components such as multiplexers, shift registers… I'd like to make a TTL CPU, but the more I look at it, the more it seems I'll have to make my ALU without the 74181 —I don't like relying on discontinued parts that may be hard or impossible to source in the near future.