2600: The Hacker Quarterly, Spring 1991

The 1991 volume, whose Autumn issue printed "Simplex Locks: Illusion of Security," the article that put a mechanical lock among the magazine's cover subjects and drew replies for the next twenty years.

Spring reports the sentencing of Len Rose in "The Terminus of Len Rose," with an Atari virus, a Soviet BBS list, a UNIX password hacker, internet outdials and "The New LEC Order." Summer asks "Where Have All The Hackers Gone?" and covers magnetic stripes, MCIMAX, a tone tracer project, "More on the CLASS Struggle" and a review of Katie Hafner and John Markoff's Cyberpunk. Autumn adds "Dutch Hacker Intrusion," "Protecting Your SSN," "Postal Hacking," "Psychology in the Hacker World" and useful UNIX programs. Winter runs the crypt() source, class features, a COCOT column, mobile frequencies, "Gulf War Printer Virus," "Major Telco Privacy Hole" and "Human Database Centers."

The Simplex piece produced a Simplex and USPS update in the same volume and a full sequel two decades later, "Simplex Locks: Illusion of Security, Version 2.0," in the Winter 2011 issue.