I was wondering what "core" means? CPU or memory or both?


Like most terms, it depends on context.

  • The term cpu core is frequently used these days. It refers to one of the independent processing units of a multi-core processor.

  • The term core memory is a leftover from an early form of random access memory (RAM). Magnetic core memory was first patented in 1947 and was used in early computers through the 50s and 60s. According to Wikipedia's article, magnetic core memory was replaced by integrated silicon RAM chips in the 1970's. Unlike modern silicon RAM, core memory was non-volatile -- it retained its contents indefinitely without power.

  • i think the only places you run into the "core memory" term these days is in the mainframe world and computer history books. it's not generally used in the pc world. for more info on multi-core CPUs check other posts in the multi-core tag – quack quixote Jun 4 '10 at 12:55
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    Except when a program on *nix crashes and leaves behind a core file, which is a dump of its memory. – Ignacio Vazquez-Abrams Jun 4 '10 at 14:51
  • @ignacio: it's possible the etymology of "memory core dump" came from "core memory", but it's not the same term. – quack quixote Jun 4 '10 at 15:11
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    @quack quixote: Oh, that's DEFINITELY where the term "core dump" came from. For a bit, ferrite core RAM or "core" was the only RAM there was. Having actually used ferrite core RAM based computers (albeit only as a student long, long, long, ago), I don't even pause for thought when I see the term "core dump". I have to make an effort to remember that the terminology has no context for those who have no experience with a computer which did NOT use semiconductor RAM. (Gives you an idea of how old those snippets of code are, no?) – irrational John Jun 4 '10 at 17:15
  • @irrational John: Did core dumps actually exist back when core memory was used? (If so, did they consist of the actual core memory?) – SamB Jun 4 '10 at 20:35

The word "core" has multiple meanings. These days, it's mostly used to refer to the actual processing units within the CPU (now that they tend to have more than one), but it used to be that "core" referred to the amount of memory, not processing units, in a machine. Hence the term "core dump," which refers to a readout of memory as of just before a crash.


A core is a processing unit. It may or may not have a number of caches (small quick memory) of its own, depending on the design of the chip. What most people consider 'the memory' (ie the main RAM) is not directly connected to the idea of a core.


Some further read :

From what I understand, one or more core are part of a processor (CPU).

Memory can refer to the cache (a small and faster type of memory) or the RAM. The RAM isn't part of the CPU.

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