28 Mar
2008
28 Mar
'08
2:50 p.m.
jim s wrote:
Also as far as the Mac roms are concerned Apple never
published them in
any form, and may in fact have them under a copyrighted "unpubliished"
form which cannot be legally reverse engineered as was the IBM BIOS.
Actually, having purchased a Macintosh 128 that contained those ROMs,
there was no legal impediment whatsoever (at least in the US) to
reverse-engineering them.
In recent times, Sega tried to convince a court that any transient copy
of a ROM produced in the course of reverse-engineering is an infringement
of copyright, but the court rejected that concept.
If someone had really wanted to clone the Mac ROM as part of a
commercial venture, they would have needed to use two teams, one to
reverse-engineer and write specs, and a the other to write new code from
the specs. The fact that Apple published specifications (_Inside
Macintosh_) that covered much of the functionality would have helped
a lot.
A clone produced in this way would have had problems with each successive
release of Apple system software, because they implemented ROM patching
in ways that were very dependent on the locations of specific call
instructions in the ROMs. In other words, if ROM routine foo is
broken, and it calls routine bar via a vector in RAM, foo is patched
by intercepting the vector to bar, and having the patch check whether
the return address is a precise address within foo.
Eric