The IBM System/360 established architectural compatibility as a design principle — not a marketing claim. It delivered real portability across a wide performance range using microcode and custom transistor packaging. Its limitations — no ICs, partial model incompatibility, rare max-memory deployments — are as instructive as its successes.
The floppy disk is a hardware innovation that enabled portable, standardised, low-capacity digital data exchange in IBM mainframe environments. It succeeded where earlier media failed — not by being faster or denser, but by being specifiable, licensable, and physically durable enough for daily use in controlled settings.
The IBM 350 was the first production hard disk drive. It shipped in 1957. It stored 3.75 MB. It used two heads on one moving arm. It was superseded by the 1301 in 1962.