Main storage

Main storage: In a computer, program-addressable storage from which instructions and other data may be loaded directly into registers for subsequent execution or processing.

Note 1: Main storage includes the total program-addressable execution space that may include one or more storage devices.

Note 2: "Main storage" usually refers to large and intermediate computers, whereas "memory" usually refers to microcomputers, minicomputers, and calculators.

Source: from Federal Standard 1037C