Compile this in TP3. It will automatically create an overlay file ( TP3DEMO.OVR ). Run it. The screen fills with colored letters. This was state-of-the-art in 1986. Today, it is a beautiful artifact.
Released in 1985, Turbo Pascal 3.0 is widely considered the peak of the original "Turbo" era, solidifying Borland's dominance in the software development world. It was an incredibly fast, all-in-one development system that fit entirely on a single floppy disk. Key Features and Advancements turbo pascal 3
And it all fit on one disk.
Because TP3 could only hold one code segment in memory at a time (64KB limit), you used the $O overlayfile directive. You would manually design a call tree so that rarely-used procedures (error handlers, setup screens) swapped out over each other. Compile this in TP3