People did very crazy things with the 2nd processors. I had a ZX Spectrum emulator running on the Z80 2nd processor, and an Atari ST emulator on the 68000 2nd

People did very crazy things with the 2nd processors. I had a ZX Spectrum emulator running on the Z80 2nd processor, and an Atari ST emulator on the 68000 2nd processor. Both very limited, and still having to go through the BBC's 6502 display and sound. But amazingly, some 3rd party code for those machines worked well enough in the emulators to give an impression of sort of working.