The Z-80 SoftCard is a plug-in Apple II processor card developed by Microsoft to turn the computer into a CP/M system based upon the Zilog Z80 central processing unit (CPU).

This gives Apple II users access to many more business applications, including compilers and interpreters for several high-level languages.

As CP/M requires contiguous freely usable RAM from address zero - which the Apple II doesn't have, since its own 6502 CPU's call stack and zero page and its text mode screen memory cannot be outside the lowest 4 KiB of RAM - addresses are translated in order to move reserved-RAM and non-RAM areas to the top of memory.

SCP built prototypes,[7] Don Burtis of Burtronix redesigned the card, and California Computer Systems manufactured it for Microsoft.

witnessed the SoftCard's debut in March 1980 at the West Coast Computer Faire, calling it "an Apple breakthru".

[1] The SoftCard became the company's largest revenue source in 1980,[10] selling 5,000 units in three months at $349 each, with high sales continued for several years.