*BSD News Article 46691


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From: c.p.valentine@open.ac.uk (Chris Valentine)
Newsgroups: comp.unix.bsd.freebsd.misc,comp.periphs.scsi
Subject: Re: Adaptec 1542C for $125CDN -- comments?
Date: 11 Jul 1995 11:06:47 GMT
Organization: KMI, The Open University, UK
Lines: 33
Message-ID: <c.p.valentine-1107951205360001@ck328571cc2.open.ac.uk>
References: <rrwood-2106951636420001@bpci.net3.io.org> <DAy5Et.8uD@watserv1.uwaterloo.ca> <3t01b9$m0i@panix.com> <3t93eo$brd@anshar.shadow.net> <3ta5uj$614@panix.com>
NNTP-Posting-Host: ck328571cc2.open.ac.uk

In article <3ta5uj$614@panix.com>, jbrock@panix.com (John Brock) wrote:

> I was under the impression that the bounce buffers only cost you a few
> percent in terms of speed, but I could easily be wrong here.  Can you
> give me any idea how much it would reduce the speed of the card if you
> went from, say, 16MB to 20MB?  Would it still be faster than a
> non-busmastering adapter (and by how much)?

I have a Pentium 75MHz (GiGabyte motherboard) with 32Mb RAM that boots
from one of two SCSI-2 drives connected to an Adaptec 1542-CF. So, yes it
works, but how much speed am I loosing?

I notice that I'm getting all sorts of problems with video playback. With
Video for Windows 1.1e, sometimes a movies just won't play, sometimes the
sound jerks everytime there's HD activity. I wonder if this is being
caused by the DMA problem. This did not go away when I temporarily fitted
an IDE drive, installed DOS 6.2 and Windows 3.1 on that and booted from
it. The movies on the SCSI HDs still played naff.

I have also noticed that my capture capacity (fps) had gone *down* in
going from 486DX-33 with 8Mb RAM to the Pentium - I wonder if this is why?

I guess you guys would recommend getting a PCI SCSI-2 card, but the cost!!
Anyone recommend something other than Adaptec, that is also cheaper? I'm
note using any esoteric operating systems (OK, I admit, its mostly a games
machine!).

Chris.

Multimedia Enabling Technologies,
The Knowledge Media Institute,
The Open University, UK
http://kmi.open.ac.uk/met/METHome.html