27 Mar
2008
27 Mar
'08
4:02 p.m.
Jim Leonard wrote:
Chuck Guzis wrote:
I worked with a
number of people who worked for Phoenix and have also
worked with people who who have had to make the BIOS work. it also is
not so much that the routines have to be the same place, but the data
tables do as well for things to work. Many drivers will go thru the
bios table and find the routine then tables for various functions. They
would fail if the signature was different or the tables didn't match.
Many times the code that does this was in other rom drivers as well.
It became simpler to just put all as near the same spot as possible and
do away with such problems that way.
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.
IBM did not come after the copiers until a stable clone of the BIOS
appeared and the market demanded that IBM keep compatability with the model.
Only marginal changes such as the AT updates took hold with few of the
updates to the model which was in the originally closed PS2 design ever
got traction.
If Apple had ever let a reverse engineered version of their hardware out
of their control take hold, they would have had the same situation as
IBM w/o the resources to survive the competition.
--
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* note my email address is changing to jws at jwsss.com
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Actually, a lot of people spent a lot of time
reverse-engineering the
IBM BIOS. You really don't get a sense of this until you realize
that Phoenix not only made sure that the functionality of the BIOS
routines was the same, but that the routines themselves were located
at the same place in memory.
Having them in the same place in memory seems like a big waste of
time. I can't think of a single instance in which knowing where the
routines are located in memory can help me write a faster or smaller
program.
If the routines do the same thing, and are at the same place in ROM,
how different enough (to avoid copyright) from the originals could
they be? It's been a while since I looked at the tech ref listings
but they didn't seem all that horribly written (I know others will
disagree, I myself found a bug in the cursor handling in my 5160 ROM,
but that's not the point -- the point is that they weren't SO terrible
that they could be significantly improved or made smaller)...