How restore correct black screen mode?
 

If I run a program that does something like change the character set of the black screen, e.g. aview, then, after the program has executed, the black screen is still using the new charachter set, making it unreadable.

Ditto if it does something to vga, like Doom2 or zgv - the vga image viewer, the black screen in left in the new vga mode and is unreadable.

So how to return the screen to correct mode?

TIA.

Type "reset"

Thought I'd tried that. Any road your post has the stamp of authority about it so I'd better try it again.:)