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From: chris@mimsy.UUCP (Chris Torek)
Newsgroups: comp.unix.wizards
Subject: Re: How to add partition table under ULTRIX 2.0
Message-ID: <7885@mimsy.UUCP>
Date: Thu, 6-Aug-87 10:36:37 EDT
Article-I.D.: mimsy.7885
Posted: Thu Aug  6 10:36:37 1987
Date-Received: Sat, 8-Aug-87 12:46:10 EDT
References: <3653@ecsvax.UUCP>
Organization: U of Maryland, Dept. of Computer Science, Coll. Pk., MD 20742
Lines: 20
Keywords: ultrix,partition

In article <3653@ecsvax.UUCP> dcw@ecsvax.UUCP (Douglas C. Wilson) writes:
> 		0x25644036,	rd54_sizes, ...
> I have figured out the last 5 hex digits from comparing the drives listed.
> 	44= ascii "D" for the rD drive
> 	036 = 54 since it is a "54" drive

You are on the right track, but the encoding is not ASCII.  The
magic number 0x25644036 is the `media ID' as returned by Get Unit
Status commands.  It is made up of five 5-bit fields and one 7-bit
field.  The 5-bit fields encode either a blank (0) or one uppercase
letter in A..Z (1-26); 0x25644036 expands to `DU' `RD '.  The last
seven bits represent the drive number, here 54.  Since RA81s are
`DU' `RA ' 81, I get 0x25641051.

I do not know why DEC uses this media ID field instead of the (more
sensible to me) drive type identifier also found in Get Unit Status
end messages.
-- 
In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 7690)
Domain:	chris@mimsy.umd.edu	Path:	seismo!mimsy!chris