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From: brand@janus.UUCP
Newsgroups: comp.sys.att
Subject: PC6300 hard disk and controller questions?
Message-ID: <21066@ucbvax.BERKELEY.EDU>
Date: Thu, 1-Oct-87 19:14:49 EDT
Article-I.D.: ucbvax.21066
Posted: Thu Oct  1 19:14:49 1987
Date-Received: Sat, 3-Oct-87 03:10:35 EDT
Sender: usenet@ucbvax.BERKELEY.EDU
Reply-To: brand@janus.UUCP (Graham Brand)
Organization: University of California, Berkeley
Lines: 27
Keywords: hard_disk hard_disk_controller

I have a number of questions about hard disk drives and controllers
in general and those of the PC6300 in particular. I have a 2 year old
PC6300 with a dealer installed 20MB HD and controller (Western digital 
or Data Technologies Corp., I am not sure.) One or the other
has just gone bad and so I am looking at the prospect of having to 
replace it. I had thought about using the diagnostic disk that came 
with DOS (2.11 in my case) but was told by the AT&T hardware rep. that
the disk will not work if "optional ROM" is present. When I boot up
the message does say "Optional ROM at C8000....etc", I cant't remember
the exact details. I must admit, though, that I haven't noticed any
extra boards in the machine when I have taken off the cover - apart from
the video and disk controller boards that is. 

As a result I have a few questions:

(1)	What exactly is this "Optional ROM" and what does it do?
(2)	Where does it reside physically - on the motherboard, on a
	separate memory board?
(3)	Could I not have any Optional ROM and still get this message?

(4)	How do I use the diagnostic disk (or other means) to confirm 
	which item is defective (HD or controller)?
(5)	If it is the hard disk, I may want to replace it with a 30 MB.
	Might there be any problem in doing this?

Any assistance would be greatly appreciated.
-Graham Brand (brand@janus.berkeley.edu)