Path: utzoo!mnetor!tmsoft!torsqnt!news-server.csri.toronto.edu!bonnie.concordia.ca!uunet!wuarchive!udel!mmdf
From: wjb%cogsci.COG.JHU.EDU@vm1.nodak.edu
Newsgroups: comp.os.minix
Subject: Re: IDE disks
Message-ID: <44839@nigel.ee.udel.edu>
Date: 16 Feb 91 19:00:43 GMT
Sender: mmdf@ee.udel.edu
Lines: 37


Mike Ching says:

>IDE stands for something like Integrated Drive Electronics which means
>the controller is integrated with the drive. MFM, RLL, and ESDI describe
>the interface between the controller and the drive.

	Yes, but in the AT BUS world they also imply that you use a
controller which implements the Western Digital register set and provides
the PROGRAMMING interface to the drive.  Minix doesn't care what the actual
hardware interface is as long as it implements the right registers for the
progammer.  There are even SCSI controllers out there which implement the
right interface.

> IDE and SCSI describe
>the interface between the system and the controller on the drive.

	SCSI is actually a bus rather then a drive interface.  SCSI
"controllers" for PCs implement a way to generate SCSI bus transactions.
The interface they provide to the program running in your machine
varies.  As I said above at least one is specialized for SCSI disk
transactions and provides WD compatibility for your programs.

	My understanding of IDE is that most (all?) of them just run an
extender off of the AT BUS to the drive.  In many cases they then implement
the WD registers on the drive.  I'm not convinced that "many" means "always".

>I have
>not found any software that does not treat an IDE drive the same as an
>external controller including those that do low level formatting like
>Spinrite.

	I know someone who builds clones and he HAS found IDE drives that
don't work with Spinrite.  As I said in my last message, Spinrite is a good
test, but not all IDE drives pass.  Ask first.

				Bill Bogstad