[b409ba0801cd21]

That was true of the DSP-1, but not true of the SuperFX or SA1.

The DSP-1 was a preprogrammed microcontroller that preformed certain calculations that would have been inefficient to preform on the SNES CPU. The inputs were written to a memory mapped location, and the outputs read back. An interposed copier could simply redirect these reads and writes.

The SuperFX and SA1 used the cartridge's ROM and RAM for program and data, and therefore these enhancement chips are placed between the SNES bus and the cartridge memory. The cartridge memory is unavailable to the SNES bus while the enhancement chip is executing, as in the SuperFX, or the the enhancement chip enters wait states while the CPU is accessing the cartridge memory, as in the SA1.

[planteen]

Ah gotcha. My memory is getting hazy. I had a floppy disk copier many years ago and remember using Mario Kart to play other games. I thought it was SuperFX but I was wrong.