Editing Hard disk drive (section)

=== 1970s ===
In 1973, IBM introduced a new type of HDD code-named "[[IBM 3340|Winchester]]". Its primary distinguishing feature was that the disk heads were not withdrawn completely from the stack of disk platters when the drive was powered down. Instead, the heads were allowed to "land" on a special area of the disk surface upon spin-down, "taking off" again when the disk was later powered on. This greatly reduced the cost of the head actuator mechanism but precluded removing just the disks from the drive as was done with the disk packs of the day. Instead, the first models of "Winchester technology" drives featured a removable disk module, which included both the disk pack and the head assembly, leaving the actuator motor in the drive upon removal. Later "Winchester" drives abandoned the removable media concept and returned to non-removable platters.

In 1974, IBM introduced the swinging arm actuator, made feasible because the Winchester recording heads function well when skewed to the recorded tracks. The simple design of the IBM GV (Gulliver) drive,<ref>"Design of a Swinging Arm Actuator for a disk file" J. S. HEATH IBM J. RES. DEVELOP. July 1976</ref> invented at IBM's UK Hursley Labs, became IBM's most licensed electro-mechanical invention<ref>US 3,849,800 Magnetic disk apparatus. Cuzner, Dodman, Heath, & Rigbey</ref> of all time, the actuator and filtration system being adopted in the 1980s eventually for all HDDs, and still universal nearly 40 years and 10 billion arms later.

Like the first removable pack drive, the first "Winchester" drives used platters {{convert|14|in}} in diameter. In 1978, IBM introduced a swing arm drive, the IBM 0680 (Piccolo), with eight-inch platters, exploring the possibility that smaller platters might offer advantages. Other eight-inch drives followed, then {{convert|5+1/4|in|abbr=on}} drives, sized to replace the contemporary [[floppy disk drive]]s. The latter were primarily intended for the then fledgling personal computer (PC) market.