At the end of the article are two links: https://xeroxalto.computerhistory.org/index.html https://xeroxalto.computerhistory.org/xerox_alto_file_system...

The first is the actual archive; the second is a "walkthrough" with pointers to various interesting things.

(I'm the author of the blog post, walkthrough and archive. Al Kossow was responsible for rescuing the files in the first place.)