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From: cd5340@mars.njit.edu (David Charlap)
Newsgroups: comp.lang.pascal
Subject: Re: Capturing a ega text screen.
Message-ID: <1991Mar28.043613.28596@njitgw.njit.edu>
Date: 28 Mar 91 04:36:13 GMT
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In article <25045@hydra.gatech.EDU> gt0652b@prism.gatech.EDU writes:
>I am writing a program that needs to be able to shell out to dos and then come
>back again with the screen intact. There must be some way to store the 
>contents of the screen in ram and then redisplay the screen quickly
>when the shell is done.

Simple.  Any 80 column screen is 4000 bytes long (80x25 characters + 80x25
attributes).  A color mode screen (CGA, EGA, VGA text) begins at location
$B800:0000, and a monochrome screen (MDA, EGA mono, VGA mono) begins at
location $B000:0000.

All you need to do is declare 4000 bytes like this:

Var
	Buffer : Array[1..4000] of byte;

and move the screen data into it like this:

Move (Mem[$B800:0], Buffer, 4000);

Restore the screen by moving it back.  Like this:

Move (Buffer, Mem[$B800:0], 4000);

It's that simple.  If you're in a monochrome mode (check if lastmode=7)
then use address $B000:0 instead of $B800:0, and it'll still work OK.

--
David Charlap                   "Invention is the mother of necessity"
cd5340@mars.njit.edu            "Necessity is a mother"
Operators are standing by	"mother!" - Daffy Duck