Thirty-five years after the Apple II personal computer changed the course of technology, the original DOS source code has been made public.
With permission from Apple and program author Paul Laughton, the Computer History Museum and Digibarn Computer Museum announced the release of the original 1978 code.
Laughton, a contracted programmer from Shepardson Microsystems, wrote the Disk Operating System (DOS) in just seven weeks. "When Woz showed me the designs of the disk controller hardware and software driver, I was truly amazed," Laughton wrote in a personal essay recounting his work with Apple.
Bucking the system, which required large cards with dozens of large- and small-scale integrated circuits, Wozniak built a controller that required only seven small-scale circuits and offered significantly better performance.
"When Woz started this design, he did not look at how other people had done it," Laughton said. "He thought about how it should be done." By April 1978, a $13,000 (£8,110), one-page contract had been signed, with the promise of a 15 May Apple II delivery.
"I knew what needed to be done, and I knew how to do it," Laughton told the Computer History Museum. "I was confident that I could do it pretty quickly."
The first Apple II delivery — complete with DOS 3.1 — was made in early June.
But DOS was not what we, by today's standards, call a true "operating system." According to Laughton, the initial vision for the computer was a code-it-yourself structure that allowed users to open, read, write, and close files.
The source code that's been released is a scan of the original documents in Laughton's personal library.