Turbo Pascal used it for the overlay implementation (for DOS) -- overlays = virtual memory at home. TP 5.0 from 1988 was the first version that had it. The id

Turbo Pascal used it for the overlay implementation (for DOS) -- overlays = virtual memory at home. TP 5.0 from 1988 was the first version that had it. The idea was to make sure the code the CPU returned to would actually be in memory. I'm pretty sure Windows 1.0 did something very similar.