CRAM
(1) (Chalcogenide RAM) See phase change memory.(2) (Card Random Access Memory) An early magnetic card mass storage device from NCR that was made available on its 315 computer systems in 1962. It offered reasonably reliable random access storage at a time when magnetic tapes with sequential access were the primary storage medium.
A Mechanical Wonder
CRAM used a removable cartridge housing a deck of 3x14" cards with a magnetic recording surface. There were initially 256, and later 512, cards in the deck, providing 5.5MB and 11MB of storage. With a roomful of 16 units connected to the computer, the total storage capacity was 176 megabytes, a rather large amount of random access capacity for that era.
With air blowing over them to keep them apart, the notched cards were suspended from eight rods that were selectively moved to release a specific card. The card was dropped and wrapped around a rotating drum using air pressure. After reading or writing, it was returned to the cartridge. Every once in a while, two cards dropped at the same time, causing a loud halt to the operation. See RACE and Data Cell.
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| CRAM Units |
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| NCR's CRAM was a successful addition to its computer line, offering reliable random access during the 1960s. By the end of the decade, magnetic disks were becoming mainstream. (Image courtesy of NCR Corporation.) |
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| The Card Drop |
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| Separated by jets of air so the card could fall freely, a card was released to the read/write head by moving the rods. (Image courtesy of NCR Corporation.) |
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