Comment by VLM
13 hours ago
Ironically the Z80 is a nibble ALU. That's why its so slow compared to the competition, an 8 bit add on a "2 MHz" Z80 takes as much clock time as a 8 bit add on a "1 MHz" 6809.
13 hours ago
Ironically the Z80 is a nibble ALU. That's why its so slow compared to the competition, an 8 bit add on a "2 MHz" Z80 takes as much clock time as a 8 bit add on a "1 MHz" 6809.
The Z80 is pipelined and thus has a higher latency but also higher throughput. Besides, memory was the bottleneck, in particular instruction fetches, so multicycle instructions made more sense. Related article: https://news.ycombinator.com/item?id=6341137