In my TI databook, they're both ALU and/or Function Generators (a rose by any other name :), identical except for the carry/overflow logic. Hope that makes both of you happy. Allison (and sorry for not noticing that you're the exception, gender- wise, Sellam's feminine side notwithstanding), I ran across a thread here last year where you mentioned the Signetics 3000KT8080SK bit-slice board; don't suppose you did ever find any documentation? I've got one here that's pretty useless except as a source of TTL chips, since it's all socketed. m -----------Original Message------------ an Really, my TI databooks have it as the lookahead carry generator for the 381 ALU.