I recently learned that the IBM Z series mainframes are generally compatible with software written …

I recently learned that the IBM Z series mainframes are generally compatible with software written for the legendary IBM 360 launched in 1964. While I'm sure there are caveats, maintaining any backward compatibility with a platform from over 60 years ago is impressive. Having started in 8-bit microcomputers and progressing to various desktop platforms and servers, mainframes were esoteric hulking beasts that were fascinating but remained mysterious to me. In recent years I've started expanding my appreciation of classic mainframes and minis through reading blogs and retro history. This IEEE retrospective on the creation of the IBM 360 was eye-opening. https://spectrum.ieee.org/building-the-system360-mainframe-n... Having read pretty deeply on the evolution of early computers from the ENIAC era through Whirlwind, CDC, early Cray and DEC, I was familiar with the broad strokes but I never fully appreciated how much the IBM 360 was a major step change in both software and hardware architecture. …