Date: Thu, 8 Oct 1998 12:17:51 +0200 From: Ignatios Souvatzis <ignatios@theory.cs.uni-bonn.de> To: Christoph Weber-Fahr <listmail@helena.callcenter.systemhaus.net>, Wolfgang Helbig <helbig@Informatik.BA-Stuttgart.DE> Cc: freebsd-isdn@FreeBSD.ORG Subject: Re: what's wrong with a1 and irq 2 ? Message-ID: <19981008121751.D13500@cs.uni-bonn.de> In-Reply-To: <199810080944.LAA29460@helena.otelo-call.de>; from Christoph Weber-Fahr on Thu, Oct 08, 1998 at 11:44:08AM %2B0200 References: <199810080638.IAA00402@RVC1.Informatik.BA-Stuttgart.DE> <199810080944.LAA29460@helena.otelo-call.de>
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On Thu, Oct 08, 1998 at 11:44:08AM +0200, Christoph Weber-Fahr wrote: > Hi, > > (IRQ 2 is occupied by the second interrupt controller on an ISA system) > > Yep. The 'cascade interrupt'; I'm well aware of this, but this > doesn't keep quite some periphery from using it. > > > IRQ 2 on the card's side is IRQ 9 on the processor's side.^ > > Does this mean the A1 should work with IRQ 9 despite it is jumpered > for IRQ 2 ? yes, thats how ATs are wired. The ISA bus line formerly connected to IRQ 2 (on the only interupt controller of the IBM XT) is now connected to IRQ 9 (on the 2nd interupt controller of the IBM AT and up). There was no IRQ 9 (none of 8-15) wired on the XT. Some hardware devices' documentation still use the "IRQ 2" name, which would be right for the IBM XT, but on AT and higher machines the same interupt line creates the CPU's IRQ 9 vector. (And there is no supported method to create the real IRQ 2). Take this with a grain of salt: I only have an Amiga, a DraCo and 2 Sharks at home, no PC. Regards, Ignatios Souvatzis To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-isdn" in the body of the message
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