Chepponis@CMU-CS-C.ARPA (02/22/84)
From: Mike Chepponis <Chepponis@CMU-CS-C.ARPA> kevinw, Try doing a 32-bit by 32-bit multiply, or a 64-bit by 32-bit divide on a 68k in a single instruction...You can do this on real 16-bit micros, like the Z8003/4. The Z80 does in fact set condition codes on the 16-bit ADC HL,ss and SBC HL,ss instructions. But as I've mentioned on this list before, the Z80 has a 4-bit ALU. This explains why, for instance, a JP PLACE instruction, 3 bytes, takes 10 clock cycles, while a JR PLACE instruction, 2 bytes, takes 12 clock cycles (relative jumps are slower than absolute jumps). But all this really doesn't matter - It's the system response time that counts. Most of us don't write in assembly language anymore unless we really have to, so which processor is being used is not important. (A 500 MHz Z80, mythical indeed, would provide good performance, I imagine!) -Mike -------