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From: jca@pnet01.cts.com (John C. Archambeau)
Newsgroups: comp.sys.ibm.pc
Subject: Re: RLL controllers with MFM drives
Message-ID: <665@crash.cts.com>
Date: 7 Nov 89 05:36:54 GMT
Sender: root@crash.cts.com
Organization: People-Net [pnet01], El Cajon CA
Lines: 79

wayne.ho@f526.n250.z1.fidonet.org (wayne ho) writes:
>Hello,
>    I may have been mistaken here.  I heard read it somewhere in another 
>echomail conference and thought it came from a reliable source.  I 
>have no proof with this, so until anyone else has information on SEAGATE 
>and RLL stuff, I won't worry about it.
> 
> > Oh, by the way.  Seagate is not going to develop anymore
> > MFM or RLL drives.
> > The ST151 was Seagate's last MFM drive developed.  Seagate
> > is now focusing on
> > SCSI drives so now this problem of MFM and RLL will be
>
> > done with as soon as
> > the older MFM and RLL drives die out from normal usage.
> 
>So SCSI is the way to go??  I was thinking about purchacing a SCSI 
>controller and drive for my 386sx, but I have been warned against purchacing 
>a 16-bit SCSI controller.  Again, I don't know if this is true or not, 
>but someone told me that the 16-bit SCSI doesn't not work that well. 
>I was considering an 8-bit SCSI controller, what do you think?  Also, 
>what types of SCSI drives does Seagate have out at the moment?  If 
>you have any specs such as speed and size that would be nice to know. 
>Thanks in advance.
 
Not quite yet.  I wouldn't buy a SCSI hard drive unless your motherboard has
a built-in SCSI port (I have seen some) or until companies such as Western
Digital design a good 16-bit or 32-bit SCSI host adaptor.  There might be such
a beast out now.  I think I remember seeing an ad for a 32-bit SCSI host
adaptor in a magazine (MIPS?), but I can't for the life of me remember who
made it.  As for which SCSI drives Seagate has out now, they have the
following:

5.25" (these are basically SCSI implementations of their MFM/RLL
counterparts):

ST225N (20 Mb), ST251N (40 Mb), ST277N (60 Mb), ST296N (80 Mb)

3.5" Drives:

ST125N (20 Mb), ST138N (30 Mb), ST157N (46 Mb), ST177N (60 Mb)
ST1096N (80 Mb)

These are the more common units out there that I can think of from the top of
my head.  I had the latest data booklet from Seagate a week ago but I think my
one of our assinine sales reps ate it or gave it to a customer.  The newer
3.5" drives by Seagate have an average seek of about 24ms which is better than
the old STblah-1 units with only 28ms.  I do recall seeing some drives with a
20ms seek in that booklet, but that's just a vague memory since my primary
concern was with the newer 3.5" drives.  I just bought an ST151 which is
basically a 3.5" version of the ST251-1 with a seek of about 24ms.  I like it
and until the SCSI host adaptor card is resolved with the IBM compatables
entirely, I will stick with MFM and RLL drives for the time being.  I'm not
convinced of the reliability of SCSI ports for the IBM compatable domain as of
yet.  I do know that Seagate does make pretty sloppy drive controllers and
host adaptors.  I base this on the fact that they recommend an interleave of
3:1 on an AT and 4:1 on an XT while I can easily get a 2:1 with my WA3-16 (a
WD1003-WA2 clone more or less) or a WD1006V-MM2 that I just put in an Arche
Rival 286-12 today.  I do admit that Seagate makes good drives, but I don't
like their controller and host adaptor boards.  In that department I'm partial
to Western Digital.  When WD makes a 16-bit SCSI host adaptor that's been
around for awhile, then I might contemplate a SCSI hard drive, but not till
then.
 
When Seagate Dealers and Distributors can't order the MFM and RLL drives
anymore, then I would start to break my piggy bank for a SCSI host adaptor and
SCSI hard drive, but not until I see that bridge on the horizon which probably
won't be for a few years to maybe a decade depending on where the demand is.

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