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From: jensen@muscat.UUCP (Paul Jensen)
Newsgroups: net.unix-wizards
Subject: Re: Cpu ID under UNIX
Message-ID: <111@muscat.UUCP>
Date: Wed, 13-Nov-85 20:01:13 EST
Article-I.D.: muscat.111
Posted: Wed Nov 13 20:01:13 1985
Date-Received: Wed, 20-Nov-85 08:32:12 EST
References: <138@oracle.UUCP>
Organization: DEC Western Region TBU, Santa Clara, CA
Lines: 37

If you want to access the VAX SID register in order to generate a unique
per CPU number, it will not work.  The format of the VAX SID register is

            31        23     14      11           0
           +---------+------+-------+--------------+
           |  type=1 | ECO  | plant | serial #     |  for a 780
           +---------+------+-------+--------------+

            31        23        15        7       0
           +---------+---------+---------+---------+
           |  type   |    0    | uc rev  | hdw rev |  for most other VAXes
           +---------+---------+---------+---------+

Even for the 780, there are only 4096 unique serial numbers per plant,
and I suspect this has rolled over many times.  As for getting the
number itself, you need to be in kernel mode to execute the MFPR
instruction: this is a relatively straightforward kernel hack.

If your main interest is generating a unique number, you might
instead try reading the physical ethernet address of your DEUNA
(assuming you have one).  Be forewarned, that even a unique number
will not protect proprietary software against the clever (& privileged)
end-user.

Regards,


					/Paul Jensen


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