Apple DOS - Decline of Apple DOS

Decline of Apple DOS

After 1980, DOS entered into a state of stagnation, along with all other Apple II products, as Apple concentrated its efforts on the ill-fated Apple III computer and its SOS operating system. After the Apple III had been abandoned by the company, two more versions of Apple DOS, both still called DOS 3.3 but with some bug fixes and better support for the new Apple IIe model, were released in early and mid 1983.

Without third-party patches, Apple DOS could only read floppy disks running in a 5.25-inch Disk II disk drive and could not access any other media, such as hard disk drives, virtual RAM drives, or 3.5-inch floppy disk drives. The structure of DOS was such that it was not possible to have more than 400kB available per drive without a major rewrite of almost all sections of the code; this was the main reason Apple abandoned DOS in 1983, when Apple DOS was entirely replaced by ProDOS.

ProDOS retained the 16-sector low-level format of DOS 3.3 for 5.25 inch disks, but introduced a new high-level format that was suitable for devices up to 32 MB in size; this made it suitable for hard disks and 3.5-inch floppies. All the Apple computers from the Apple II Plus onward can run both DOS 3.3 and ProDOS, the Apple II Plus requiring a "Language Card" memory expansion to use ProDOS; the Apple //e and later models had built-in Language Card hardware, and so could run ProDOS out of the box. ProDOS included software to copy files from Apple DOS disks. However many people who had no need for the improvements of ProDOS (and who did not like its much higher memory footprint) continued using Apple DOS or one of its clones long after 1983. The Apple convention of storing a bootable OS on every single floppy disk meant that commercial software could be used no matter what OS the user owned. A program called DOS.MASTER enables users to have multiple virtual DOS 3.3 partitions on a larger ProDOS volume, which allowed the use of many floppy-based DOS programs with a hard disk.

Apple stopped authorizing user groups to distribute DOS 3.3 many years ago, but granted one company, Syndicomm, an exclusive license to resell DOS 3.3.