"Joel" wrote: > There were two different 65c02s. > They both added extra, but different, commands over the old 6502. > The Rockwell 65c02 will not run software that needs the version of the 65c02 > Apple used. Wrong. The Rockwell R65C02 instruction set is a superset of that used by the WDC 65C02 (and clones thereof). It should be perfectly capable of being used in an Apple II and will run all software which expects a "standard" 65C02. The Rockwell variant adds 64 extra opcodes (all hex values x3, x7, xB and xF) which deal with manipulating or testing individual bits in zero page locations. These instructions are not compatible with the 65802 and 65816, which used the same opcodes for different purposes. -- David Empson dempson@actrix.gen.nz