Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!sun-barr!newstop!texsun!pollux!attctc! From: kgallagh@digi.UUCP (Kevin Gallagher) Newsgroups: comp.sys.ibm.pc Subject: Re: MFM as an RLL drive? Summary: Miniscribe 3650 in use as an RLL drive. Message-ID: <284@digi.UUCP> Date: 13 Dec 89 23:51:05 GMT References: Reply-To: kgallagh@digi.UUCP (Kevin Gallagher) Distribution: comp Organization: DSC Communication Corporation Lines: 40 ath: digi!kgallagh In article mlm@cs.brown.edu writes: > > Is it possible to use a MFM hard disk drive with an RLL > controller? Are there particular MFM drives that will do it? > How would I tell? > About a year ago I installed a Miniscribe 3650 drive (40 Meg half height MFM drive) in my PC clone. I connected it to an Adaptec ACB-2072 RLL controller. The drive is rated as an MFM drive, but I understand that Miniscribe uses the same platters in the 3650 as they do in their 60 Meg half height RLL certified drive. (Over a year ago, in Steve Gibson's column in Infoworld, Steve mentioned that he had formatted quite a few 3650's as RRL drives using Adaptec's AT RLL controller, and never had a problem.) So, I decided to give the Adaptec XT RRL controller a try. (Keep in mind that other MFM drives use a differ surface on their platters which cannot hold an RLL format.) The disk drive states it has 809 cylinders, with the parking zone in cylinder 852. Steve indicated that he formatted each of his drives out to cylinder 840 without any problems. On an AT, that got him two full 32 Meg partitions, 16 sectors per track. I used the built in controller firmware low level format utility to format the drive out to 840 cylinders. I ran into no problems at all. The XT controller, however, formats only 25 sectors per cylinder, saving the 26th as a spare in case it encounters a problem formatting that cylinder. This meant that my 840 cylinders came up short of two full 32 Meg partitions. So, I decided to reformat using 850 cylinders. It succeeded without a hitch. I then used the Dos 3.3 version of FDISK to partition the drive into two partitions, each of which is just a tiny bit short of 32K. I have never had a problem. I ended up with about 63 Meg on a 40 Meg drive that cost me under $400. ----------------------------------------------------------------------- Kevin Gallagher attctc!digi!kgallagh or apcihq!apcidfw!digi!kgallagh -----------------------------------------------------------------------