I'm building my own 8-bit CPU from TTL chips, and this caused me to think: how were 32-bit minis built in the late 70s and early 80s? In particular, how was the ALU built? I know about the 74181 4-bit ALU, and I know (from reading A Soul of a New Machine) that PALs were also used.
Did companies get custom chips fabricated, or was it all off-the-shelf chips with a few PALs sprinkled in? Thanks, Warren
