Apple II processor cards (or co-processor cards) were special cards that could be used to allow the
Apple II to use different processors on the (otherwise) same
computer hardware. This allowed other operating systems to run on the Apple II.
Here are some processors that were available on
coprocessor cards for the Apple II:
^James Hinds, CHIEF DESIGNER & PRESIDENT, Stellation Two, Inc. 1/1980-6/1985 – invented, designed and produced THE MILL and Vitamill coprocessor circuit boards for Apple // computers for this manufacturer of hardware and publisher of software
for Apple // Computers.