Path: utzoo!utgpu!cunews!bnrgate!bigsur!bnr-rsc!bcarh471!pdwalker
From: pdwalker@bcarh471.bnr.ca (Paul D Walker)
Newsgroups: comp.sys.ibm.pc
Subject: Re: MFM -- RLL drive
Message-ID: <3368@bnr-rsc.UUCP>
Date: 25 Sep 90 19:51:44 GMT
References: <2a81P1w162w@zooid.UUCP>
Sender: news@bnr-rsc.UUCP
Reply-To: pdwalker@bcarh471.UUCP ()
Organization: BNR Ottawa, Canada
Lines: 59

In article <2a81P1w162w@zooid.UUCP> dve@zooid.UUCP (David Mason) writes:
>Hello all. I asked this question a while ago on another system, but didn't 
>get a decent answer at the time. So, here goes.
>
>I have a 70 mb 28ms full height Micropolis 1330 (I think, or 1335) hard 
>disk. It currently has an MFM controller. I was told by a couple of 
>individuals that it would be safe to RLL this drive (to about 110mb, I 
>think), and a couple of other people told me this drive could NOT be safely 
>RLL'd. I'd like to know the "real" answer. I called what support Micropolis 
>had here in Canada (not much) and only recieved a very vague answer. So can 
>someone give me an authoritative answer? The drive has no errors on it at 
>all (I've checked it with a couple of programs) and is about 2 years old 
>(possibly older, I bought it used). The drive is constantly full, and I 
>could really use the extra 30 megs.
>
>Thanks.

I asked the same question about 8 months ago when there was a large rage
on about MFM vs RLL and what could be done and not done.

After listening to the arguments, I decided to go out and buy a RLL controller
for my AT.

In the 8 months since I have had the card, I have sucessfully formatted and
used 2 Seagate 251 type 40 hard drives as 65 meg drives.

I have also sucessfully used a 110 meg Priam (type 9) hard drive as a 170 meg
drive for 3 months with absolutely no problem.

Other than the increase in disk space that I got from this, I have increased
my DTR (data transfer rate) from 250k/sec to 715k/sec.

Now, I am sure that we are going to hear from some people about how it is EVIL
to have done this, and that my warrenty has been voided (I have none) and that
my drives are going to melt down and be destroyed at any time.  Hogwash.

I will say that on an older drive, using a RLL controller MAY cause you some
problems.  However, I am of the opinion that the drives made today are of 
a good enough quality (with both timing and precision) that they can easily
handle the increased timing demands of an RLL controller.

Notice that both types of drives that I have used are of a known 'good quality'

My controller is a DTC 7287

If you have a good hard drive, (access time <= 40ms) then go out and get the 
card.  I doubt that you will have a problem.

Dont forget to change the interleave (usually 1:1) to get the enhanced
throughput.

PS: by the way.  If you are crammed up at 70meg of disk space, then the 
    extra 30 meg you will fill up in a short order.  :)

/****************************************************************************
 * Paul D. Walker               PHONE : (613)765-2590                       *
 * Bell-Northern Research, Ltd. BITNET: pdwalker@bnr.car                    *
 * Ottawa Ontario Canada        USENET: ...!uunet!bnrgate!bcarh471!pdwalker *
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