Before IBM created its personal computer, two types of computer systems,
Apple II and CP-M, dominated the microcomputer world. Neither of these
systems were PC compatible, or Mac-compatible (the two primary standards
in place today). The original IBM PC became a new standard in the
microcomputer industry. Since then, hundreds of millions of
PC-compatible systems have been sold, as the original PC grew into a
large family of computers and peripherals. More software has been
written for this computer family than for any other system on the
market.