From: Sengan Baring-Gould <sengan@seqnet.net>
  To  : ggi-develop@eskimo.com
  Date: Thu, 25 Feb 1999 20:37:12 -0700

Re: STB and S3 tech specs

Jon M. Taylor wrote:

>        It is actually an information theory thing, at least that it how
> it was explained to me.  Just take the register spec, hook the chip up to
> a specialized logic analyzer, and have it start feeding every data
> permutation through the registers.  By observing what registers change
> when and how, you'll quickly be able to get a good enough idea of the
> basics of how the chip works to be able to figure out the rest by hand if
> necessary.  And information theory _guarantees_ that you can always
> determine the chip design 100%, given enough time, with a logic analyzer
> and register spec only.

Do you realise the search space on that? Keep you busy for a year or  2.


       On the Slashdot forum attached to the notice of my being hired by

> Creative, someone brought up an example I wasn't aware of: the Weitek
> P9000 video chipset.  Now, Weitek was best known for making math
> coprocessors.  How'd they come up with one graphics chipset design out of
> the blue?  By reverse engineering some proprietary Sun chipset, that's
> how!  Sun accidentally released a .h file with the full register spec for
> the chipset on some version of Solaris, and Weitek had a 100% compatible
> clone up and running in no time flat.  It was so good, it was even
> bug-for-bug compatible!!  So this is NOT unjustified paranoia.  People
> *have* gotten burned - BADLY burned - many times in the past on this
> very issue.

Hmm... let me be very sceptical that they reverse engineered it from the
chip. Either that or it was a god-damn simple chip. If they did reverse
engineer it, I don't see why the .h file was such a help. As previously
stated: if you can hook into the kernel and see how it does stuff, you'll
be able to work out what the API is.

> > for everything else data books are freely available.
>
>         Not for the EMU10K (SB Live DSP).  Or any of Creative's other
> audio chipsets, actually!  All existing drivers were created from specs
> that were themselves created by reverse-engineering back in the DOS
> days.  Something will have to be done about that eventually - my boss
> says that he can almost guarantee that none of the existing drivers are
> 100% 'compatible', although I am sure that (especially on the older SB,
> SBPro, etc) it is so close to 100% that it doesn't really matter.

Ya. ;-)

Sengan