Category: <b>video</b>
<p>
<pre><b>INT 10 - TopView - GET SHADOW BUFFER</b>

	AH = FEh
	ES:DI -&gt; assumed video buffer
		B800h:0000h color text/CGA graphics, B000h:0000h mono text,
		  or A000h:0000h EGA/VGA graphics (RSIS environments only)
Return: ES:DI -&gt; actual video buffer for calling process
Desc:	Determine the address of the virtual screen to which the program
	  should write instead of the actual video memory; this permits
	  programs to be multitasked without interfering with each other's
	  output, and allows memory managers to move the video memory to
	  permit larger programs to be loaded.
Notes:	if no multitasker or RSIS-compliant environment is installed, ES:DI is
	  returned unchanged; RSIS is the Relocated Screen Interface
	  Specification
	for display pages other than 0, use AH=05h and AH=0Fh to determine
	  whether a particular page exists
	TopView requires a call to AH=FFh to notify it that the screen has
	  changed; DESQview will check for changes itself until the first call
	  to AH=FFh
SeeAlso: AH=05h,AX=5201h,AH=FFh,INT 15/AX=1024h,INT 21/AH=2Bh"DESQview"
SeeAlso: INT 21/AH=ECh"DoubleDOS"
</pre>