need to query BIOS for available video modes

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#2065

From: Tom Reingold
Date: Tue, 04 Sep 1990 19:34

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I am writing an application that allows the user to switch into 132
column mode if she wants to.  New EGA cards and VGA cards support this
option.  The pseudo code to accomplish this is

	AH = 0
	AL = 0x55
	int 10

But I don't know how to detect if this mode is available on the video
board.  A user could have any video board in existence.

QUESTION:  Is there a way to test for the availability of this
feature?

Running this code when the feature isn't there gives a very weird
screen and sometimes hangs the PC.  This is undesirable.
--
	Tom Reingold
	tr@samadams.princeton.edu
	rutgers!princeton!samadams!tr
	201-577-5814
	"Brew strength depends upon the
	 amount of coffee used." -Black&Decker

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Path: arc1-ca.pugleaf.net!utzoo!utgpu!news-server.csri.toronto.edu!rutgers!njin!princeton!cs!samadams.princeton.edu
From: tr@samadams.princeton.edu (Tom Reingold)
Newsgroups: comp.os.msdos.programmer
Subject: need to query BIOS for available video modes
Message-ID: <2423@rossignol.Princeton.EDU>
Date: 4 Sep 90 19:34:20 GMT
Sender: news@cs.Princeton.EDU
Organization: Noo Joizy -- The Cultural Mecca
Lines: 23