Xref: utzoo rec.games.programmer:3417 comp.os.msdos.programmer:4646
Newsgroups: rec.games.programmer,comp.os.msdos.programmer
Path: utzoo!utgpu!watserv1!watcgl!anicolao
From: anicolao@watcgl.waterloo.edu (Alex Nicolaou)
Subject: Write Mode 1 on EGA/VGA cards
Message-ID: <1991Apr15.061148.29923@watcgl.waterloo.edu>
Organization: Computer Graphics Laboratory, University of Waterloo, Ontario, Canada
Date: Mon, 15 Apr 1991 06:11:48 GMT
Lines: 34


 I know that it is possible to do the following on EGA and VGA cards, 
but am not clear on the exact step by step actions you need to do it.
I would love it if someone has a ready made source example that does this
or would be willing to write one - my problem is that although I am 
proficient in C and C++, I can barely code in assembly. So here's
the problem/program I need solved/written:

	1. Draw an image on an off-screen area of video memory
	2. Set the card into "Write Mode 1"
	3. Use a fast machine instruction to copy the block
	  containing the off screen image onto the screen (MOVSW)
	4. Restore the card to the previous write mode

Now, if anyone can provide me with ANY code written in ANYTHING (excepting
fortran :-) that does this, I want to read it. Please mail it to me!

I am operating under the following constraints:

	1. I would like to draw off screen using the Borland graphics
	  functions, but don't know if it clips to the screen boundaries
	  or not.

	2. I want the code I eventually produce to run on an 8088 (and
	  therefore it will run on anything better, too).

If anyone out there wants to / can construct a working example using
Turbo C or Borland C++ with inline assembly, it would be very very
appreciated.

Thanks,

alex