After watching the Did You Know Gaming video about the NES, they mentioned that when they were deciding what CPU to use for their Famicom, they wanted to have it be able to play their arcade games and they wanted to just have to change the memory addresses and be able to port them just like that. However they decided to go with the 2a03. Why didn't they go with the z80? I know that they used the 2a03 because it had built in audio, but if it was a custom chip, then why did they choose to go with a 6502 core instead of a more practical z80? was it because of price?