Apple DOS
Apple computer running a Hello World program
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| Developer | Apple Computer |
|---|---|
| Written in | Assembly |
| OS family | Apple DOS |
| Working state | Discontinued |
| Source model | Closed source |
| Initial release | 1978 |
| Latest release | 3.3 / 1980 |
| Kernel type | Monolithic kernel |
| License | Apple Software License Agreement |
Apple DOS is the family of disk operating systems for the Apple II series of microcomputers from late 1978 through early 1983. Apple DOS has three major releases: DOS 3.1, DOS 3.2, and DOS 3.3; each one of these three releases was followed by a second, minor "bug-fix" release, but only in the case of Apple DOS 3.2 did that minor release receive its own version number, Apple DOS 3.2.1. The best-known and most-used version is Apple DOS 3.3 in the 1980 and 1983 releases. Prior to the release of Apple DOS 3.1, Apple users had to rely on audio cassette tapes for data storage and retrieval, but that method was notoriously slow, inconvenient, and unreliable.
When Apple Computer introduced the Apple II in April 1977, the new computer had no disk drive or disk operating system (DOS). Although Apple co-founder Steve Wozniak designed the Disk II controller late that year, and believed that he could have written a DOS, fellow founder Steve Jobs decided to outsource the task. The company considered using Digital Research's CP/M, but Wozniak sought an operating system that was easier to use. On 10 April 1978 Apple signed a $13,000 contract with Shepardson Microsystems to write a DOS and deliver it within 35 days. Apple provided detailed specifications, and early Apple employee Randy Wigginton worked closely with Shepardson's Paul Laughton as the latter wrote the operating system with punched cards and a minicomputer.
There was no Apple DOS 1 or 2, per se. Versions 0.1 through 2.8 were serially enumerated revisions during development, which might as well have been called builds 1 through 28. Apple DOS 3.0, a renamed issue of version 2.8, was never publicly released due to bugs. To the dismay of many programmers, Apple published no official documentation until release 3.2.
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