Path: utzoo!attcan!uunet!portal!cup.portal.com!cliffhanger
From: cliffhanger@cup.portal.com (Cliff C Heyer)
Newsgroups: comp.arch
Subject: Re: *big iron*
Message-ID: <22860@cup.portal.com>
Date: 7 Oct 89 21:46:32 GMT
References: <7981@cbmvax.UUCP> <11538@burdvax.PRC.Unisys.COM>
  <22488@cup.portal.com <1016@cavs.syd.dwt.oz> <8124@cbmvax.UUCP>
Organization: The Portal System (TM)
Lines: 24

Cliff wrote...
>>	Yes, they (IBM and DEC - and all the rest, including DG) will
>>save the bandwidth and fast i/o for the *big iron* machines AND the
>>high-end "workstations".  This is just what the main problem is!  The
Robert Cousins responded....
>If you decide that $8000 is high end, then you are right, but frankly,
>I think your facts need to double checked.  There are currently only 4 
>DG 88k workstations which all have approximately the same I/O bandwidth.
>While I will admit that it is quite fast, the I/O performance of the 
>low end is almost the same as the high end.  The major difference is in
>CPU speed.

The "high end" is the SERVER with the VME bus. Note that the "low cost"
VME bus TO be introduced for the workstations is alleged not to do block I/O,
thus limiting it's throughput.

>DMA is a must for performance at any level whenever you have
>more than one task running at a time.

Yup, which is why I've been looking for a 386 board maker that has put
an ESDI or SCSI controller "on board" and bypassed the AT-bus with
direct DMA channel(s). (Like the Amiga.) So far, looks like the Mylex
MX386 is the only one (?)  Hoping if I subscribe to Computer Architecture 
News I might learn more!