24 Jul
2006
24 Jul
'06
6:09 p.m.
Tony Duell wrote:
A 74S182 is only a 16 pin DIL package, and would give you lookahead
carry. Take a look at the PERQ 2 schematics on bitsavers -- the 16K CPU
board diagrams are there. And look at the PERQ CPU Techref also on
bitsavers. The PERQ is a 20 bit machine using 74S181 ALUs, and the carry
circuit should be applicable to you.
If it's interesting, the MIT CADR has a 32 bit alu using the 74181 and
uses the '182 for carry. The schematics are also on bitsavers. It's a
reasonably general microcoded 32 bit cpu. Not bad for it's day.
Also, I have verilog for the 181 and 182 if you go that way :-) I like
to simulate... (I have verilog for the whole cadr to be honest, but that
seems off topic)
-brad