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From: timothym@tekigm2.UUCP
Newsgroups: comp.sys.ibm.pc
Subject: Re: RLL controller
Message-ID: <1435@tekigm2.TEK.COM>
Date: Tue, 3-Feb-87 20:18:10 EST
Article-I.D.: tekigm2.1435
Posted: Tue Feb  3 20:18:10 1987
Date-Received: Thu, 5-Feb-87 05:24:15 EST
References: <1083@ethos.UUCP> <1373@bnrmtv.UUCP> <2622@iuvax.UUCP>
Reply-To: timothym@tekigm2.UUCP (Timothy D Margeson)
Organization: Tektronix, Inc., Beaverton, OR.
Lines: 38
cc: timothym@tekigm2

>In article <1373@bnrmtv.UUCP> perkins@bnrmtv.UUCP (Henry Perkins) writes:
>>I'm using an Adaptec RLL controller with a generic (i.e., cheap) hard
>>disk in my Compaq DeskPro.  It works fine, and I'm now getting 30 Mb
>>instead of 20 Mb ... BUT I can't boot from hard disk anymore, since

The problem may well be in how you formatted the hard disk. The BIOS that
is located on the disk controller is what sets the disk parameters, the 
system BIOS on the motherboard only calls the HD BIOS when HD specific calls
are made (actually the call is made anytime a disk request is made, and the
HD BIOS then passes control back to system BIOS if the request is for floppy
disk I/O), otherwise the controller has full and absolute control of what goes
onto and off of the hard disk. All of the interface between the system and the
controller deals in absolute cylinders and absolute sectors, but internal to
the Adaptec 2070 the cylinder and sector count is converted to the proper
logical sector then back into a relative head, cylinder, and sector number 
that applies to the RLL encodeing technique.

The only thing that will affect booting is if the sector conversion in the
Adaptec wil not let the OS write the correct sector for some reason. This is
fairly unlikely... unless the sector is marked as defective which (by using RLL
on a 'cheap' drive) is very likely.

So, either you have formatted the disk improperly, or, cylinder 0, head 0, and
sector 1 is marked defective.


Good luck... (if you see the message XXXX bytes in bad tracks when you run
CHKDSK, the problem is more than likely the second case). Oh yeah, I also
recommend doing LOTS of backups until you are absolutely certain your data
isn't slowing fading into the magnetic void (common on disks not designed
or tested for RLL - Adaptec should have a notice to this effect in their
documentation).

-- 
Tim Margeson (206)253-5240
PO Box 3500  d/s C1-937                          @@   'Who said that?'  
Vancouver, WA. 98668
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