Despite having so few transistors, the 6502 is generally viewed as twice as fast (or more) as the Z80 for the same clock speed [https://www.cpcwiki.eu/forum/amstrad-cpc-hardware/the-cpc-revision-zero-article/msg243843/ Source]. Two reasons can explain it:
* The 6502 has an 8-bit ALU while the Z80 has a 4-bit ALU.
* The 6502 has a built-in clock doubler, allowing it to perform 1 internal operation and 1 memory access per full-cycle. In contrast, the Z80 can only do at most one memory access per M-cycle, which takes 3 to 6 T-states. On average, a 2MHz 6502 can make 2 memory accesses per microsecond, while a 4MHz Z80 can only make 1 in the same time.
The 6502 comes in a 40-pin DIP package. It has been produced by various manufacturers and used in a wide range of applications, from gaming consoles like the [[Atari 2600|Atari VCS]], [[Atari Lynx]], [[Nintendo Entertainment System]] and [[PC-Engine]] to personal computers like the [[Apple II]], [[BBC Micro]], [[Oric]], [[VIC20]] and [[Commodore 64]].