I think, it wasn't so much for speed as for then expensive extra circuitry. (On the few vintage instruction sets using ones' complement, I know, addition and su

I think, it wasn't so much for speed as for then expensive extra circuitry. (On the few vintage instruction sets using ones' complement, I know, addition and subtraction still executes in the same time as any other internal ALU instruction. Then, cycle times were still mostly owed to slow core memory cycles and the fasted you'd ever get was a single memory cycle.)