Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!wuarchive!decwrl!sgi!shinobu!odin!anchor!olson
From: olson@anchor.esd.sgi.com (Dave Olson)
Newsgroups: comp.sys.next
Subject: Re: New 320Meg SCSI drive, 16ms, $950 (quantity purchase)
Keywords: CDC-Imprimis Wren IV
Message-ID: <11083@odin.corp.sgi.com>
Date: 29 Jul 90 03:20:42 GMT
References: <5429@darkstar.ucsc.edu> <45808@brunix.UUCP>
Sender: news@odin.corp.sgi.com
Organization: Silicon Graphics, Inc.  Mountain View, CA
Lines: 33

In <45808@brunix.UUCP> rca@cs.brown.edu (Ronald C.F. Antony) writes:
...

| If CDC uses the same numbering scheme as in the Wren V, VI and VII
| series, as I think, the number after the dash shows the unformatted
| capacity, i.e. in this case 307 MB. So the drive can hardly have 320
| formatted capacity.
| Most ppl tend to forget, that 1 MB = 1024^2 bytes and neither
| 1000*1024 (which would be 1000 KB) nor 1000^2 bytes. In computers
| there is not the metric system used where m and mega stand for 1000^2.
| Note also, that in the metric system the letters are lower case where
| as the K in KB and the M in MB are upper case...

Wrong on two counts.  The number WAS (before Seagate bought Imprimis)
the formatted capacity in Megabytes, where a Mb was defined as
1000000 (10^6) bytes, NOT 1048576 (2^20).  Immediately after Seagate
bought Imprimis, the 94171-344 was renamed 94171-376, where 376 was
the unformatted capacity.  The only 94171-307 I had seen was a very
early version of the 94171-344; so I can't shed any more info on
that.  Depending on how the drive was formatted, the 94171-344 had
a formatted capacity of ~644000 sectors ~= 322 2^20 Mb ~= 337 10^6 Mb
I seem to recall that the 344 Mb value was with no spares whatsoever,
and also included the cylinders reserved for the embedded controllers

Many mfg's are defining their Mb as 10^6, including most of the
3 1/2" drive mfg's.  To avoid ambiguity, talking about number of
available blocks is often useful (assuming the blocks are 512 bytes,
which is USUALLY how the numbers are quoted).
--

	Dave Olson

Life would be so much easier if we could just look at the source code.