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From: vsnyder@jato.jpl.nasa.gov (Van Snyder)
Newsgroups: comp.sys.atari.st.tech
Subject: Re: MFM hard drive help
Message-ID: <1991Mar13.190748.26529@jato.jpl.nasa.gov>
Date: 13 Mar 91 19:07:48 GMT
References: <523@gcc.uucp> <12052@hydra.Helsinki.FI> <91072.145300GERLOFF@DB0TUI11.BITNET>
Reply-To: vsnyder@jato.Jpl.Nasa.Gov (Van Snyder)
Organization: Jet Propulsion Laboratory, Pasadena, CA
Lines: 42

In article <91072.145300GERLOFF@DB0TUI11.BITNET> GERLOFF@tubvm.cs.tu-berlin.de (Olaf Gerloff) writes:
>In article <12052@hydra.Helsinki.FI>, luoto@cs.Helsinki.FI (Markku Luoto) says:
>>
>>I opened it once and the drive was a seagate... but how can you tell wether
>>it's a mfm or something else ???
>>
>
>Hello Markku!
>
>If the drive was a Seagate it is very easy: Look at the drive type on the cover
>If the last character was a digit, it was a MFM drive (e.g. ST 225, 20 MB
>5 1/4 inch MFM drive). If the last character was a R, it was an RLL drive
>(e.g. ST 238R, 5 1/4 inch 30 MB RLL drive).

From the Seagate Catalog, page 27:
none = ST412 MFM
A = AT bus
X = XT bus
N = SCSI or SCSI-2 (SCSI-2 is downward compatible with SCSI).
ND = Differential SCSI or SCSI-2
NM = Macintosh compatible SCSI
V = NetWare ready
R = ST412 RLL
E = ESDI
J = SMD-O/E or SMD-E (dual port)
K = IPI-2 (dual port or enhanced dual port)
S = synchronized spindle

Probably more junk than ST owners need to know.  But now if you see one in
a surplus store, you'll know what you're up against:  for example, there's
essentially no hope of connecting an SMD drive to an ST.  ND won't work without
some different kinds of bidirectional buffers -- the "plain" SCSI is "single
ended";  differential SCSI lets you have 10 meters of cable, single ended SCSI
lets you have 3 meters (according to the standard, but on my Mac IIci, it
craps out with about 2 or 2.5 meters total cable).  NM might also be trouble
on a typical Supra/ICD/Berkeley ST interface.


-- 
vsnyder@jato.Jpl.Nasa.Gov
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