Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!xstor!bang!iverson
From: iverson@bang.uucp (Tim Iverson)
Newsgroups: comp.periphs.scsi
Subject: Re: Scsi Controllers
Keywords: Scsi Controller Query
Message-ID: <1991Feb09.052143.1873@bang.uucp>
Date: 9 Feb 91 05:21:43 GMT
References: <1459@tsdiag.ccur.com>
Reply-To: iverson@xstor.com
Followup-To: comp.periphs.scsi
Distribution: na
Organization: House of the Smoking Gun
Lines: 41

In article <1459@tsdiag.ccur.com> jeffp@tsdiag.ccur.com (Jeff Pelosi) writes:
>  I am considering purchasing a Scsi controller.  I would appreciate
>  getting some recommendations.  I know one person who has an Always
>  IN-2000.

Last I saw an Always board (6 months ago?), they were engaging in some very
shady practices - both engineering and marketing.  They advertised that their
board had a phenomenal transfer rate.  Well, I checked it under DOS with
CoreTest and a wimpy little seagate capable of at most 200KB/s.

Surprise, CoreTest came back with 1.2MB/s!  This is flatly impossible, they
must have been doing something fishy.  So, I dusted off soft-ice and
observed their BIOS firsthand.  Aha!  Caught in the act - they disable
*all* interrupts while transferring data.  This means the clock doesn't tick,
which means (to CoreTest) that transfers take no time at all.

It also means that your serial port can loose data while writing to disk
(like in an old PC jr.), and that other programs that depend on clock ticks
or other asynchronous interrupts won't work correctly, if at all.

Now, unless they have some *very* dumb hardware, there is no reason to do
this other than to cause an abnormally high transfer rate.  It is obviously
not a programming error - interrupts are enabled up until the transfer,
where they do a deliberate cli, followed by the transfer, followed by sti.

>  I like the price point of this controller ($189.00 at Computability).

You're kidding.  An Adaptec 1542B can't cost much more than this and I know
Future Domain TMC830s are much cheaper - a better card for DOS (especially
with windows) than the Adaptec.  For unix, you will not be able to live
without a 1542, not unless you really know what you're doing.

>Jeffrey Pelosi         Concurrent Computer Co.        Fax:201-870-5952
>jeffp@tsdiag.ccur.com  2 Cresent Place  MS117         Phone:201-870-4223

- Tim Iverson
  iverson@xstor.com -/- uunet!xstor!iverson


BTW, now you'll be able to tell your friend why her time-of-day clock is
so slow all the time :-}.