Card Random Access Memory
Introduced by NCR in 1962 the CRAM was the first mass storage device.
It offered reliable random access storage at a time when magnetic tapes were the primary storage medium. Up to 16 CRAM units could be online.
Each CRAM unit held one 5.5MB cartridge that contained 256 mylar, 3x14" cards with a magnetic recording surface. The cards were suspended from eight rods, which were selectively moved to release a specific card. The card was pulled out, wrapped around a rotating drum and read or written. The drum had 56 fixed read / write heads.
Control panel from the NCR 315 CRAM unit.