> Nintendo also had something I think is a great idea when developing the NES: the video hardware had its own bus to the cartridge. This probably saved many cyc

> Nintendo also had something I think is a great idea when developing the NES: the video hardware had its own bus to the cartridge. This probably saved many cycles keeping the processor busy with other things instead of transferring content to the video RAM. It also allows better use of the system's very limited RAM and video RAM. Nintendo did this because they had to, not because it was an ingenious innovation. Sega didn’t do it in the SMS/GG for the same reason Nintendo didn’t do it in the GB or GBA; because those architectures were much more efficient at ferrying data due to their high cycle counts. The Z80, for the most part, at 4MHz is about equivalent to a 6502 at 1MHz due to architectural differences / differing design decisions. Except in strictly loop-based copies, since it can move more data in the same sliver of time, especially if you utilize ported memory.