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 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: Organization: Total disorganization. MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII 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 Download OpenDOS, then: CDD C:\^DEL /ZS MSDOS.SYS IO.SYS \DOS\*.*