FTL Design
History of Technology

1974 Ampex Core Memory

Not all that long ago, magnetic core memory was standard high-speed working storage (random-access memory, or RAM) for computers and accounting machines. Introduced in the early 1950s, by the mid-1970s core was mostly obsolete, replaced by semiconductor memory.

The images below show details of a core memory board made by Ampex in 1974 and used in an NCR book-keeping machine. Mounted on a 13" x 9.5" plug-in board, 36 modules of core type 1801-10 (each measuring about 1" x ¾") stored 8,192 (8K) 18-bit words, the equivalent of 18KB of 8-bit storage.

Modern PCs typically have 4GB or more of RAM on a couple of 5" x 1" memory cards, about 233,000 times as much memory occupying about a tenth of the board area, a storage ratio of approximately two million to one.

Click on each image for a larger view

Four of the thirty-six core modules on the board

Single core module

Detail of core module showing individual ferrite beads

Last revised: 31 May, 2015