Today marks the 55th anniversary of IBM’s announcement of the System/360 line…which made obsolete virtually all of its then-existing products. The 360 line established a common architecture for machines of widely-differing price and performance characteristics, with the individual product implementations of this architecture differing considerably. The goal was compatibility, so that customers could upgrade without extensive rewriting of programs. Consolidating IBM’s diverse computer systems into this single system architecture was a bold decision; truly, a bet-the-company decision: in the end, it paid off, with devastating consequences for the ‘Seven Dwarfs’ who were IBM’s competitors at the time…but the implementation was frighteningly stressful. A good article on the project recently appeared in IEEE Spectrum.