The Xerox Alto computer was important because it was the first attempt and a making a machine that was visual rather than text based. It used a mouse and a WYSIWYG word processor. It was this beastie which was ripped off by Steve Jobs
Conservationists behind making the code available to the public had to archive it to nine-inch tape, before being transferred to eight-millimetre cartridges and then put on CDs. Then they had to get permission to release the code.
The file includes the Bravo word processor, Markup, Draw and Sil drawing programs, and the Laurel e-mail program. There’s also the BCPL, Mesa, Smalltalk, and Lisp programming environments along with various utilities and the Alto’s Ethernet implementation.
Ethernet was developed for the Alto system using networking software, called Pup (for PARC Universal Packet). This anticipated the Internet by allowing multiple Ethernet local area networks to be interconnected by leased phone lines, radio links, and the ARPANET (which at this time connected a handful of computers at ARPA research centres).
You can look at the software here