Overlay files?

Originally Posted by dj-siba

use DOS command copy

Copy /b Main.EXE + Overlay.OVL

Hi,
Thanks for the reply.
But may I ask you about the way you managed to make this file?

"Overlay.OVL"
The fact is that,the use of this file is unknown to me.

My problem mostly is about the basics of Overlay strcuture and the aim of using it.
Also if someone can cover some information about the principles of Overlay that will be great.

Best Regards,
Android.