Xref: utzoo comp.sys.m6809:882 comp.os.os9:122
Path: utzoo!utgpu!water!watmath!clyde!att!rutgers!mit-eddie!uw-beaver!uw-june!uw-entropy!dataio!pilchuck!ssc!happym!rwing!bdw
From: bdw@rwing.UUCP (Brian Wright)
Newsgroups: comp.sys.m6809,comp.os.os9
Subject: Re: Hard Drives
Summary: RLL vs. MFM
Keywords: COCO OS9
Message-ID: <358@rwing.UUCP>
Date: 13 Sep 88 21:21:45 GMT
References: <1129@cbnews.ATT.COM>
Distribution: na
Organization: Very Little Organization, Seattle WA
Lines: 37

In article <1129@cbnews.ATT.COM>, mdk@cbnews.ATT.COM (Shadow) writes:
> 
> Can anyone tell me what the difference is between an RLL and non-RLL hard
> drive system?  What does the RLL stand for?  What are the differences
> between the controllers?  I've noticed this term used in the advertisements
> for Frank Hogg Labs when they are discussing the Burke & Burke system.
> 
> Thanks,
> Mike King
> 
> -- 
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> UUCP:..!att!cbnews!mdk1          |    OS9> iniz .signature
> Domain: mdk1@cbnews.ATT.COM      |    OS9> shell i=/.signature&
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

First, you need a basic understanding on the two methods used by the
controller.  MFM is the older format, used on floppies and hard drives.
It provides for about 32 or more (256 byte) sectors per track.  RLL is
a newer encoding method, that will squeeze up to 48 or more sectors
per track.  But, in order to use the latter, you must have a hard drive
that is certified for RLL encoding.  Plus, the price difference isn't that
much.  I glanced at an issue of Computer Shopper, and Hard Drives International
has a 20 megabyte Seagate kit, w/controller and mounting hardware, for $244,
and a 30 megabyte kit is $269.  The latter uses RLL encoding, and the media
is certified for RLL use.  I will be ordering my kit from them, since that's
the best price that I've seen for complete kits.  It's really a godsend that
we have Burke & Burke selling an interface that can use IBM XT controllers,
since they're so durn common!

Hope this helps you out!

-- 
Brian Wright
UUCP: {backbones}!uw-beaver!tikal!toybox!rwing!bdw
      "                         "!camco!eskimo!bdw
"I'd buy that for a dollar!"  --Robocop