Subject: Re: pciide, DMA, and the alpha...
To: Peter Seebach <>
From: Thor Lancelot Simon <>
List: port-alpha
Date: 08/11/1999 21:41:48
On Wed, Aug 11, 1999 at 07:39:55PM -0500, Peter Seebach wrote:
> Someone once told me he didn't think the alpha was very happy with EIDE.
> I'm wondering if that's true or not.  I'm using a PC164, if it matters;
> I could also put in a PCI UltraDMA card, if that would matter.

My pc164 is running pretty much Fine with an IDE disk.  In fact, it boots
from it.  No problems so far.  The CMD0646 controller onboard the pc164
doesn't do Ultra-DMA, though -- it doesn't really matter, since the UDMA
disks step down to the "plain old" DMA modes.  Somewhat more CPU 
utilization, and you lose the CRC over the data that UDMA does, but it 
works and it's a lot better than PIO.

> BTW, I'm a bit confused by the alpha environment - do I run out of interrupts
> on an alpha the way I do on a PC?  I notice that IRQ's I've never seen
> available on a PC seem to be showing up - for instance, my ethernet is on irq
> 2.

You don't "run out of" interrupts on anything with a PCI bus, you can 
share one interrupt between as many devices as you like.  Some ancient PC
hardware can't cope with this (and even some modern Windows device
drivers can't!) but it's broken.