From:	mharris AT blackwidow DOT saultc DOT on DOT ca
Date:	Sun, 2 Feb 1997 14:37:56 -0500 (EST)
Reply-To:	mharris AT blackwidow DOT saultc DOT on DOT ca
To:	Hamilton Feltman <ham AT slip DOT net>
cc:	djgpp AT delorie DOT com
Subject:	Re: Is there an interrupt on vertical sync?
In-Reply-To:	<32f52f30.14440371@news.slip.net>
Message-ID:	<Pine.LNX.3.95.970202143612.7397A-100000@capslock.com>
Organization:	Total disorganization.
MIME-Version:	1.0

On Sun, 2 Feb 1997, Hamilton Feltman wrote:

> Hi , I've been( programming in VGA )using allegro's Vsync to wait for
> the blit() function, but isn't there a way to generate an Interrupt
> when that vertical sync occurs? That way, I won't be wasting cycles
> constantly polling with vsync( If that's whats happening .) Would such
> an interrupt be present on most x86 hardware or  vga cards?

IRQ 2 is the vertical retrace interrupt however not all VGA cards
support it (read that most dont), also many people use IRQ 2 for other
things (my modem is on IRQ2) so using IRQ 2 for vert retrace limits
your program to a very small audience.  The best way is to use the
polling method.


Mike A. Harris        |             http://blackwidow.saultc.on.ca/~mharris
Computer Consultant   |    My webpage has moved and my address has changed.
My dynamic address: http://blackwidow.saultc.on.ca/~mharris/ip-address.html
mailto:mharris AT blackwidow DOT saultc DOT on DOT ca

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