The technocurious now can peruse the inner workings of Apple II DOS. The source code, written and released in 1978, is available for free downloads.
An interesting news for all fans of retro computing and collectibles, the source code of the famous Apple DOS, the system for cataloging disks and files on the Apple II, has been released for public download.
The initiative is an outcome of a joint disclosure of the Computer History Museum and the DigiBarn Computer Museum, which have released the source code — upon approval from Apple –for non-commercial use.
Apple II, one of the first personal computers appeared on the market and launched by Steve Jobs and Steve Wozniak in 1977, was a particularly advanced for its time: 4K of memory, support for popular monitors on the market, and the integrated BASIC system. It relied on audio cassette tapes for data storage and retrieval, which was notoriously slow, inconvenient, and unreliable method, until 1978, when Apple began marketing a 5-inch floppy disk controller.
It was Wozniak, who designed the aforementioned controller, reducing the circuits to 8 chips than competing solutions. It served a system that would allow the machine and the drive to communicate, but for the higher-level software to manage programs and data on the disk, Apple had to contact Paul Laughton, at the time employed in Shepardson Microsystems. He delivered the source code in less than seven weeks for $13,000. It was a long series of text codes, printed on pre-punched paper and ready to be loaded on the Apple II with a special instrument designed by Wozniak.
And, the download made public is in the same format (PDF and TXT files) to dream the dawn of the computer age. Apple II DOS source code is available on the Computer History Museum website while you can download additional documents such as delivery contract, systematic and circuitry design on the DigiBarn Computer Museum website.