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From: cmurcko@gvlf8-g.GVL.Unisys.COM (Chuck Murcko)
Newsgroups: comp.unix.sysv386
Subject: Re: 1024 cylinder limit for MFM drives?
Message-ID: <1990Dec14.224304.7936@news.gvl.unisys.com>
Date: 14 Dec 90 22:43:04 GMT
References: <276472BB.15476@ics.uci.edu> <1600@ulowell.ulowell.edu>
Sender: news@news.gvl.unisys.com (The NEWS user)
Reply-To: cmurcko@gvlf8-g.GVL.Unisys.COM (Chuck Murcko)
Distribution: usa
Organization: Unisys Great Valley Labs, Paoli PA
Lines: 25

In article <1600@ulowell.ulowell.edu>, mschedlb@hawk.ulowell.edu (Martin J. Schedlbauer) writes:
|> In article <276472BB.15476@ics.uci.edu> baxter@zola.ics.uci.edu (Ira Baxter) writes:
|> >I have an MFM Maxtor 2190 drive with 1224 cylinders.  I naturaly want to
|> >use all 1224 cylinders.   I am (technically cheating, but it works
|> >reliably) using an RLL WD1006SRV2 controller, and set the drive type
|> >to 1, and the cylinder count to 1224.  The ISC ADDHARDDISK script
|> >notices the 1224 cylinders, and truncates it back to 1024 with
|> >some cryptic remark about BIOS limitations.
|> >
|> >Is there no way around this?  How do ESDI, SCSI drives handle this?
|> >[I assume the "BIOS" limitations for such drives isn't present].
|> 
|> BIOS can't handle more than 1024 cylinders. You'll need a controller
|> that does sector translation. This is what is typically done for ESDI
|> drives, as they still have the same limitations. ESDI or ST506/MFM/RLL
|> makes no difference to BIOS.
|> 

It's my understanding that the 1024 cylinder limit exists in the ROM BIOS,
which, because it's not reentrant, is of little or no use to Unices. Does
this mean that ISC uses a similar setup in their partitioning software?
My experience with ESIX is that >1024 cylinders is supported. I have 1224 and
1560 cylinder partitions on my disks, WD1007SE, no translation.

Chuck