LINK can create DOS programs with “overlays.” Overlays allow sections of a program to be loaded into memory only as needed. This permits running a program that would otherwise be too large to fit in available memory. Overlay programs execute more slowly, however, since the various program modules must be swapped into and out of memory.
The CodeView debugger is compatible with overlaid modules. If you use CodeView to debug a program that has an overlay containing more than one code segment, you will see only the identifiers contained in the first segment of the overlay.