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From: berger@clio.UUCP
Newsgroups: comp.sys.ibm.pc
Subject: Re: Are there IBM compatible RLL contro
Message-ID: <16800051@clio>
Date: Fri, 20-Feb-87 13:18:00 EST
Article-I.D.: clio.16800051
Posted: Fri Feb 20 13:18:00 1987
Date-Received: Mon, 23-Feb-87 01:43:43 EST
References: <989@cartan.Berkeley.EDU>
Lines: 22
Nf-ID: #R:cartan.Berkeley.EDU:989:clio:16800051:000:873
Nf-From: clio.Uiuc.ARPA!berger    Feb 20 12:18:00 1987


You don't specify what you mean by "IBM compatible".  By their
very nature, RLL controllers aren't compatible with the standard
IBM controllers at some level.  You can't unplug a disk drive
formatted under RLL and read it with an MFM controller.

Conversely, the Adaptec 2070 and OMTI 5527 are hardware bus
compatible, and both have ROM residents that are software
compatible.  But they don't behave like the IBM controller.
For example, when reading drive parameters, IBM controllers
simply look at some jumpers which point to a table in ROM.
The Adaptec and OMTI controllers actually interrogate the disk
drive.  This is invisible to DOS, but might affect a program
that depended on complete operational compatibility.


			Mike Berger
			Center for Advanced Study
			University of Illinois 

			berger@clio.las.uiuc.edu
			{ihnp4 | convex | pur-ee}!uiucuxc!clio!berger