Next to the very real news of the Spectre and Meltdown CPU issues, it was lovely to come across Ken Shirriff's story of getting past password protection on some old Xerox Alta disk packs from the 1970s.
As further proof for why 2018 is going to be the year of blogging, two of the comments are from people who actually know about the old disks!
"I designed chips at PARC as a summer intern. You have a couple of disks from Doug Fairbairn, who was also in Lynn Conway's group."
I'm flabbergasted. That's my Alto disk you broke into!
The APL stuff is surely related to some work I did with Leo Guibas, showing why lazy evaluation would be a really good idea for implementing APL: see Compilation and delayed evaluation in APL, published January 1978. (That paper gives me an enviable Erdős number of 3, since Leo is a 2.) I'm sure it's not a complete APL implementation, just a proof of concept. It happens that my very first part-time job at PARC, in 1973, involved writing decision analysis software in APL — on a timesharing system!
Given the AATFDAFD hint, I'd guess the real password is ADDATADFAD. This derives from a project I did with Jef Raskin at UCSD in 1974. (He mentioned it in this interview.) The Data General Nova we were working with produced some garbled message with ADDATADFAD where it should have said ADDITIONAL, and it was a running joke ever after. Strange, the things that occupy some brain cells for over 40 years.
Thanks for an amusing blast from the past.
— Doug Wyatt (Xerox PARC 1973-1994)