Ferranti introduced paging on the Atlas, but the first mass-market memory pages were concepts in computer architecture, regardless of whether a page moved between RAM and disk. For example, on the PDP-8, 7 of the instruction bits comprised a memory address that selected one of 128 (2) words. This zone of memory was called a "page". This use of the term is now rare. In the 1960s, swapping was an early virtual memory technique. An entire program would be "swapped out" (or "rolled out") from RAM to disk, and another one would be "swapped in" (or "rolled in"). A swapped-out program would be current but its execution would be suspended while its RAM was in use by another program.