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Historic Apple II DOS source code now available to download

Apple's agreement with Shepardson Microsystems for Apple II DOS. | Source: DigiBarn

Thanks to a collaboration between two vintage computer museums, the Apple II DOS source code, widely regarded as the seed that sprouted Apple as we know it, has been made available to the public.

The Computer History Museum, with the help of DigiBarn Computer Museum, posted to its website on Tuesday the Apple II disk operating system for non-commercial use. Apple gave consent to the publication as the company still owns the code.

The Apple II was a fully-assembled personal computer with a number of advanced features like a built-in BASIC programming language, compatibility for an external monitor and various modes of input. However, the machine lacked a disk drive, meaning programs and data had to be stored and retrieved via cassette tape.

Apple cofounder Steve Wozniak created a floppy disk controller for the Apple II in 1977, but needed a DOS to access and organize the associated programs and data. That task was handled by contract programmer Paul Laughton, who at the time worked for Shepardson Microsystems.

In 1978, Steve Jobs inked a $13,000 deal with Bob Shepardson to provide a file manager, BASIC interface and utilities, with a delivery date pegged for some seven seeks later. Laughton said he had to write the DOS on punch card sheets, which were assembled and made into a paper tape able to be read by a plug in card created by Wozniak. The process was repeated throughout debugging and updating.

After just a few weeks of coding, Apple II DOS 3.2 was released in June 1978.

The source code can be downloaded via The Computer History Museum's website, while documents relating to the software, including schematics and business agreements, can be found on DigiBarn's site.