Path: utzoo!attcan!uunet!portal!cup.portal.com!thad
From: thad@cup.portal.com (Thad P Floryan)
Newsgroups: comp.sys.amiga.tech
Subject: Re: ESDI drives?
Message-ID: <12995@cup.portal.com>
Date: 28 Dec 88 06:54:46 GMT
References: <2067@van-bc.UUCP>
Organization: The Portal System (TM)
Lines: 43

Re: Larry Phillips' comments to my answer to Tony Sumrall's question about
ESDI on the Amiga ...

It's clear (now) that my answer wasn't clear.  (Howzat?  :-)

ST506/ST412 is "ancient".  That interface was in its heyday during the early
years of the IBM/PC.

Surprisingly, I get over 250KBytes/second from a Maxtor XT-2190 connected to
an Adaptec 4000A SCSI<=>ST506/ST412 on the Amiga using 1.3 with FFS (and the
Supra 4x4 interface).  This performance exceeds that published for most of
the "modern" systems that are reviewed in, for example, UNIX REVIEW (ref.
Compaq 386, PS/2-80, certain Sun-3, etc.)

ESDI is a modern, high speed interface, as is SCSI.  "RAW" speed of both a
modern SCSI and an ESDI interface "should be" around 750KBytes/second, but this
is not achieved in practice (likely due to an OS and its filesystem)

One caller to BBS-JC (Steven Schaem) claims DiskPerf results of over 350KBytes
per second with his ESDI drive and an Adaptec SCSI:ESDI translator on his
Amiga; you'd have to ask him for more details since I'm not in the habit of
"capturing" the message base (40-100 messages/day) on BBS-JC.

The point I wanted to make is that any cost savings (of an ESDI) drive would
be negated simply by the need to purchase a translator (such as Adaptec's) and
that one would not see any performance gains; the embedded SCSI drives
themselves are extremely fast.  Thus, the $200 saved (getting, for example, a
Maxtor XT-4380 ESDI drive instead of the XT-3380 SCSI drive) are "lost" by the
need to get a SCSI translator with attendant power cabling, ESDI cabling and
connectors, etc. (plus having one more "box" in the chain (the translator) as
a source of potential problems (interface, reliability, whatever...)).

Getting a translator for a high-performance (and LOW cost) ST506/412 drive
does make economic sense, and there's no apparent performance penalty.

Most of the people I know who've added ESDI drives to their Amigas have done
so solely because either "the drives were available at work" or "I got the
drive on an indefinite loan."  For THOSE people, it did make economic sense
to use the ESDI drive.  To date, I'm not aware of anyone making a "native"
ESDI interface for the Amiga and, due to SCSI's other advantages, I don't
foresee anyone doing so on a commercial basis (making an ESDI interface,that is)

Thad Floryan [ thad@cup.portal.com (OR) ..!sun!portal!cup.portal.com!thad ]