Hi, > 6507 is a 6502 derivitive so it is a 6502 snce the instruction >sets the same. Like the 6510. The 6507 is a cut down 6502. IIRC they only brought enough address lines out to the outside world to allow the processor to address 4K of memory. Otherwise (and from a programmer's POV) they are pretty much identical. TTFN - Pete.