magnetic-core memory

The word "Core" in the name comes from magnetic-core memory, an obsolete random-access memory technology.

The 1130 used magnetic-core memory, which the processor addressed on word boundaries, using direct, indirect, and indexed addressing modes.

The most common form of memory through the 1960s was magnetic-core memory, which stored data in the polarity of small magnets.

It was an experimental computer, used to test transistor logic circuitry and large capacity magnetic-core memory, which was completed and operational in April 1956.

Entry models had as few as 4K (4096) Bytes of Magnetic-core memory which retained their stored values even with no power.

Forrester has since observed, "It took us about seven years to convince the industry that random-access magnetic-core memory was the solution to a missing link in computer technology.

For example, each address in the IBM 1620's magnetic-core memory identified a single six bit binary-coded decimal digit, consisting of a parity bit, flag bit and four numerical bits.

The word being read would travel the one or two metres, and then because reading magnetic-core memory destroys its contents it would be sent to be re-written back to where it had been.

The bulk of the software was on read-only rope memory and thus couldn't be changed in operation, but some key parts of the software were stored in standard read-write magnetic-core memory and could be overwritten by the astronauts using the DSKY interface, as was done on Apollo 14.