Look Up Another Term

Definition: overlay

(1) A preprinted, precut form placed over a screen, key or tablet for identification purposes. See keyboard template.

(2) A program segment called into memory when required. When a program is larger than the memory capacity of the machine, parts of the program not in constant use can be set up as overlays. Each overlay called in overwrites the existing overlay in memory. Virtual memory provides for automatic overlays. See virtual memory.