Date   : Fri, 05 Jan 2007 20:24:56 -0000
From   : BBCMailingList@... (Ian Wolstenholme)
Subject: Technomatic hard disk units

I was always led to believe that using MFM drives with
an RLL controller was a "bad" thing because you were
squeezing more sectors per track onto the drive than
it was designed for.  I know that people did this a lot,
in fact the Technomatic Winchester setup does it, and
I am sure it would have been far more economical to
buy an RLL controller and MFM drive than to get an
RLL controller and drive.

I'm sure it's down to a question of reliability, and I've
read about some applications where the situation
was reversed (ie. MFM controller running RLL drive)
where reliability was critical.  These old Seagate
drives are built to last though so it's probably not
too much of an issue.

Best wishes,



Ian
 
----- Original Message -----
From: adam colley [mailto:hideki.adam@...]
To: BBCMailingList@...
Sent: Fri, 5 Jan 2007 13:46:51 +0000
Subject: Re: [BBC-Micro] Technomatic hard disk units

Hihi

On 05/01/07, Ian Wolstenholme <BBCMailingList@...> wrote:
> According to the Adaptec manual, the ACB4070 is an RLL
> controller and not an MFM-and-RLL controller (that's my
> understanding of it anyway, but I could be wrong since
> it does appear to run contrary to popular belief) so I'm not
> sure how wise is it to run it with an MFM drive.

You can run any MFM drive with an RLL controller, you'll just need to
low level format it again (to 26 sectors per track instead of 17)

This also means you'll gain around 50% extra disk space from your drive

I used to do it all the time with drives on the XT

if your drive has bad sectors you might want to think twice however as
the map will be invalid and you'd have to use something to scan the
disk and map them out again

-- 
Hideki.Adam