From: bobert@informix.com (Robert Murphy)
Newsgroups: comp.sys.mac.programmer
Subject: Re: Uniquely identifying a Mac? How?
Date: 23 Dec 92 21:15:03 GMT
Organization: Informix Software, Inc.

de19@umail.umd.edu (Dana S Emery) writes:

>In article <1992Dec17.105813.18407@jarvis.csri.toronto.edu>,
>ematias@dgp.toronto.edu (Edgar Matias) wrote:

	[discussion of serial numbers and copy/execution protection deleted]

>OK, now that would either be in a custom chip or in the Roms, but in either
>case it would be WELDED on to the logic board, right?

Nope.  It would be in some sort of PROM ("Programmable ROM") chip which
is plugged into a socket, not welded.  The only information recorded in
this PROM chip would be the serial number, which would be recorded into
the chip at the factory.  Presumably Apple would use a type of ROM that's
not erasable or reprogrammable.

>Now what happens when a logic board needs service?  Since the board now
>must stay with the machine, you have just forced all apple dealers to
>perform componant level diagnosis and repair, this is a dramatic change
>from present policy, and on which APple is likely to regard as a giant step
>backward.

The person servicing the computer pulls the PROM chip out of the socket on
the old motherboard, and puts it in the socket on the new motherboard.

>Oh, and just how would one deal with a faulty Rom chip, or a ROM upgrade
>(remember the SCSI problems in the first and second versions of the 128k
>roms?).

Since this is on a separate chip from the ROMs you're talking about, it's
not a problem.  I suppose you could get a faulty PROM, but that would be
easily replaceable.

There are, by the way, a couple of flaws with this system.  First, if you
wanted to make machine A look like it's machine B, you could crack the
case and swap the serial number PROMs.  This is not really a problem as
far as software publishers are concerned, though, because they mostly are
concerned about people running multiple copies of their program simultan-
eously on different machines, and PROM swapping still only lets you run
the program on one machine at a time.  Second, and more of interest to
pirates, is the possibility of duplicating the PROM chips.  I'm sure there
would be ways to prevent this, though, such as adding some extra functionality
to the PROM chips so that they do more than act as PROMs, and so you
couldn't just go out and buy blank PROMs and put a serial number in them
and expect them to work.

>Dana S Emery <de19@umail.umd.edu>

Bob Murphy
bobert@informix.com

P.S.  I've had to think about this stuff a lot because in the last four
years, I've written execution control code for several programs on Macs and
DOS machines using three different kinds of dongles from two different
manufacturers, and I am talking to two potential clients about doing the
same thing for them.  (For those unfamiliar, a "dongle", or "hardware lock",
is a device that you attach to some port on a computer, typically ADB on
the Mac or a parallel port on DOS.  When a protected program is running,
it can find out if the dongle is attached to the computer it's running on,
and refuse to execute if the dongle is missing.  You can copy such programs
onto 4,000,000 floppies if you want, but they'll only RUN on a computer with
the correct dongle attached.  That's why it's called "execution control",
not "copy protection".)  By the way, none of these programs have been the
sort of thing college students would likely want to pirate; rather, they've
been vertical market applications in the $3,000-$15,000 price range that
are aimed at corporations with enough money that they shouldn't need to
pirate software - but nonetheless, some of them have tried...
Newsgroups: comp.sys.mac.programmer