IBM Punch Card System
It started with a product announcement in May of 1955. IBM Corp. was introducing a product that offered unprecedented random-access storage — 5 million characters (not bytes, they were 7-bit, not 8-bit characters). This first disk drive heralded startling leaps in mass-storage technology and the end of sequential storage on punched cards and paper or Mylar tape, though magnetic tape would continue for archival or backup storage.
The disk drive was big, not quite ready for today’s laptop. With its vacuum-tube control electronics, the RAMAC (for “random-access method of accounting and control”) occupied the space of two refrigerators and weighed a ton. It stored those 5 million characters on 50 hefty aluminum disks coated on both sides with a magnetic iron oxide, a variation of the paint primer used for the Golden Gate Bridge.