Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucbvax!dewey.soe.berkeley.edu!oster
From: oster@dewey.soe.berkeley.edu (David Phillip Oster)
Newsgroups: comp.sys.mac
Subject: Re: Cloning Mac ROMS
Message-ID: <28635@ucbvax.BERKELEY.EDU>
Date: 1 Apr 89 11:48:16 GMT
References: <2782@uokmax.UUCP> <5745@cognos.UUCP>
Sender: usenet@ucbvax.BERKELEY.EDU
Reply-To: oster@dewey.soe.berkeley.edu.UUCP (David Phillip Oster)
Organization: School of Education, UC-Berkeley
Lines: 36

In article <2782@uokmax.UUCP> cbdougla@uokmax.UUCP (Collin Broadrick Douglas) writes:
>   You see, it is not as impossible as you think to clone the Mac ROMs.

Here is why a legal clone of the Macintosh ROMs is impossible:

The legal cloning process involves two teams: an analysis team and a
synthesis team.  The analysis team disassembles the ROM to be copied and
writes a spec for the synthesis team. The synthesis team writes a program
from the spec that is functionally equivalent to the original ROM.  Since
the synthesis team never sees the original code, the cloning company can
argue in court that they didn't copy the expression of an idea, and 
where the code is similar, it is because the fundamental mathematical
idea, which is uncopyrightable, is necesarily expressed this way.

Now you would think that the Macintosh ROMs would characterized by the 500
or so tooltraps and operating system traps. But, that isn't good enough.
Apple's system software on disk searches the stack to see who called it,
performs functions based on the calling address, and occasionally patches
the stack to return to some address other than the caller. Apple does this
as a way of conserving the RAM they need to correct bugs in the ROMs, but
it is, as a side effect, a great way of foiling cloning.

Now, you could, in theory take account of all of this, and write a spec
that caught every case in Apple's system software.  But, what about the
version of the system software that will come out next year?  Particularly
since Apple is free to make changes that deliberately louse up the clones,
and since the clones are prohibited by law from modifying Apple's disk
based software.

Even this you could account for by cloning the ROMs, and also the disk
based operating system software.  Try and do this in without nbeing years
behind, and without running afoul of "look-and-feel".

--- David Phillip Oster            --"When we replace the mouse with a pen,
Arpa: oster@dewey.soe.berkeley.edu --3 button mouse fans will need saxophone
Uucp: {uwvax,decvax}!ucbvax!oster%dewey.soe.berkeley.edu --lessons." - Gasee