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From: tomb@tekecs.UUCP
Newsgroups: net.arch
Subject: SASI/SCSI
Message-ID: <5148@tekecs.UUCP>
Date: Wed, 27-Feb-85 18:47:59 EST
Article-I.D.: tekecs.5148
Posted: Wed Feb 27 18:47:59 1985
Date-Received: Mon, 4-Mar-85 05:41:47 EST
Sender: tomb@tekecs.UUCP
Organization: Tektronix, Wilsonville OR
Lines: 42


		######  MUNCH   ########

By now there'll be about 10 zillion responses to this but I'll add
mine anyway.

SASI: Shugart Associates System Interface

The original! A proprietary bus structure dreamed up by Shugart
Associates to allow intelligent disk interactions. Salient features
include a 8 bit parallel asynchronus transfer and a moderatly
high level command set. Strictly a single host : one device at
a time bus.

SCSI: Small Computer System Interface (ANSI X3T9.2)

This is what happened when ANSI decided to "standardize" SASI.
First they generalized the hardware protocol adding arbitration,
deselect/reselect and allowing multiple hosts to exist on the
bus. The timing changed a little but the signal definitions
remained the same and in many systems you can use the hardware
virtually interchangeably. They also added to the software
protocols commands supporting removable or fixed random
access devices (disks), sequential access devices (tapes),
communication links, printers, ...

SCSI is rapidly becoming the interface of choice for small
system mass storage. e.g. most optical disk products are
being introduced with SCSI. Small taape drives and Higher
performance disks are tending tword SCSI. Even Xebec is
moving away from SASI to SCSI. Their "OWL" drive is now
available with SCSI interface.

Hope this helps. Also hope it's not too redundant.

Tom Beach

email:  ..!tektronix!tekecs!tomb
-- 
Tom Beach

email: ..tektronix!tekecs!tomb