Apple has effectively killed off three disk drive formats.
With the 1984 release of the Macintosh, Apple did away with industry-leading 5-1/4-inch floppy disk drives, opting instead to build a 3-1/2-inch drive into the Mac. The technology was extremely new at the time, introduced just over a year before the Mac went on sale (sound familiar?).
That made the Macintosh among the first PCs to even feature a 3-1/2 inch disk drive and the only one with a one built into the computer. But the bet was right, and within a few years, the computer industry embraced the 3-1/2 inch drive as the new standard.
Apple controversially got rid of the floppy disk drive entirely in the 1998 iMac, featuring only a re-writable CD drive. A decade later, Apple released a PC with no disk drive at all in the MacBook Air -- an obvious decision now but a big annoyance at the time.
