core

core n.  Main storage or RAM.  Dates from the days of
   ferrite-core memory; now archaic as techspeak most places outside
   IBM, but also still used in the UNIX community and by old-time
   hackers or those who would sound like them.  Some derived idioms
   are quite current; `in core', for example, means `in memory'
   (as opposed to `on disk'), and both {core dump} and the `core
   image' or `core file' produced by one are terms in favor.  Some
   varieties of Commonwealth hackish prefer {store}.