An informal generic term for floating-head magnetic disk drives in which the read-write head planes over the disk surface on an air cushion.

The name arose because the original 1973 engineering prototype for what later became the IBM 3340 featured two 30-megabyte volumes; 30--30 became "Winchester" when somebody noticed the similarity to the common term for a famous Winchester rifle (in the latter, the first 30 referred to caliber and the second to the grain weight of the charge).

[Jargon File]