Comment Re:6502 to Z80 work per clock ratio (Score 1) 167
The 6502 had special addressing modes for accessing the bottom 256 bytes of memory. Addresses in both the 6502 and Z80 were 16 bit, thus taking two read cycles to get a whole address into the CPU so that you could then get the content at the address. However, with the 6502, "zero page" addresses could be read in one read cycle. Not only that, but pairs of zero page locations could be used for indirect addressing. They could be treated as a set of (slow) address registers.
When I first came actress the Z80 after having programmed the 6502 for a while (as a hobbyist), I was quite shocked at how all over the place its design appeared to be and I actually found it a little harder to program at first because there was more to learn in order to use the CPU effectively.