Subject: Re: Oooooh... IDE to Q-bus/Unibus adapters.
To: Allison J Parent <email@example.com>
From: Jason Thorpe <firstname.lastname@example.org>
Date: 07/07/1999 16:37:09
On Wed, 7 Jul 1999 19:11:17 -0400
email@example.com (Allison J Parent) wrote:
> <think that all SCSI host adapters are as braindamaged as a 5380 with no
> <DMA, certainly not if you're comparing them to brand-spanking-new PCI
> <IDE interface chips. A more reasonable comparison would be the a
> <53c[7,8]00 series SCSI host adapter.
> Sure, but do the VS2000, 3100/m10/m30/m38 and M76 have them? NO. Qbus
> vaxen have very nice SCSI controllers that even speak MSCP for a not so
> nominal fee. Many of the systems that have SCSI do use the brain damaged
> 5380 though. In that context IDE stacks well, compared to the latest
> PCI offering, well... when did VAX get PCI?
...but also remember that you're looking at PCI IDE chips! I don't know
of a single UltraDMA IDE controller that isn't PCI. There are other
DMA-capable IDE interfaces out there, but they are usually completely
separate DMA engines glued in front of the IDE chip (e.g. those wacky
VLBus DMA boards for PCs back in the '486 era, and various workstation
products which use a "standard" IDE interface but which also support
DMA ... they supply the DMA engine that merely does the PIO to the chip
Also, AFAIK, every VAXstation that has a SCSI chip has the capability
of doing DMA to/from that SCSI chip. It is merely an issue of the NetBSD
driver for that SCSI chip not supporting DMA.
-- Jason R. Thorpe <firstname.lastname@example.org>