Core rope memory
Core rope memory , German and Fädelspeicher , is a form of read-only memory (Read-Only Memory, ROM ) for computers in the 1960s, first from early NASA - space probes and the Apollo Guidance Computer was used (AGC) designed and programmed by the Massachusetts Institute of Technology (MIT) Instrumentation Lab and built by Raytheon.
In contrast to conventional coincidence current magnetic core memories , which were then used as Random Access Memory (RAM), the ferrite cores in a core-rope memory are only used as transformers . The signal from a word line wire passing through a particular core is coupled to the bit line wire and interpreted as a binary "one", while a word line wire bypassing the core is not coupled to the bit line wire and is read as "zero".
Software written by MIT programmers was woven into core-rope memory by factory workers. Some programmers therefore called the finished product LOL memory, for little-old-lady memory.
Storage density
By the standards of the time, a relatively large amount of data could be stored in a small installed core-rope memory: 72 kilobytes per cubic foot or about 2.5 megabytes per cubic meter. That was about 18 times the amount of data per volume compared to standard read / write core memory: The Block II Apollo Guidance Computer used 36,864 sixteen-bit words of core-rope memory (in a volume of one cubic foot) and 4,096 words of magnetic core memory ( in a volume of two cubic feet).
| Memory technology |
Data per cubic foot | Data per cubic meter | ||
|---|---|---|---|---|
| Bytes | Bits | Bytes | Bits | |
| Core rope ROM | 72 KB | 576 Kbit | ~ 2.5 MB | ~ 20 Mbit |
| Magnetic core RAM | 4 KB | 32 kbit | ~ 140 KB | ~ 1 Mbit |
See also
Web links
- Pay please! The Apollo mission with 32 kilo bits - one moon and back on heise.de , viewed on July 17, 2018