Apple Disk II, the most inexpensive, easy to use floppy drive ever made was introduced in January at Winter Consumer Electronic Show. First deliveries will occur in July 1978 at $495, including the controller card.
At the time the Apple II was sold for about six months. Most users had connected their television as a colour monitor, and a cassette recorder to store their programs. A couple of weeks before, Apple had introduced a floating point BASIC (made by Microsoft) and a printer interface card.
Sadly, the Apple II cassette interface wasn't reliable and needed very accurate volume and tone adjustments, preventing owners from using the computer as a professional system.
Actually, the disk interface shown at CES was just a prototype. Final version of the Disk II interface board will be finalized a few weeks later by Steve Wozniak, and the First DOS 3 version, written by Randy Wigginton, appeared un June.
The disk II suddenly transformed the Apple II from an expensive hobbyist's toy to an efficient tool everyone could afford for home and business uses. In marketing terms, the Disk II launch can be considered as the Apple II second birth.