[rescue] Re: [geeks] THIS. MAKES. ME. SICK.

[Joshua D. Boyd]

On Thu, 14 Jun 2001, Paul Sladen wrote:
> I think somebody from Sony tried to do this with the PlayStation/2;  it's
> just a pity that they gave the Graphics/Vector unit a measly 4meg RAM, which
> means that everything has to go over the System bus from main memory if you
> want to do anything spectacular.

First, there are multiple (4 I think) vector units.  There is the IOP,
which is an R3k based system on a chip a 36mhz.  It probably doesn't have
a real vector unit, but it does have special instructions to speed 3D
calculations.

Then there is the EE and GE chip.  These are the high powered babies.
These things are based on the r5k I'm told.  Each has 2 vector units, if I
remeber correctly (I know the EE has two, I'm less sure about the GE).

Now, in addition to the system bus, there is (if I remeber correctly) a
special bus between these two CPUs.  So, while getting stuff from system
ram is slow, the EE I believe can load data from ram, process it, then
stream it over to the GE.

Most of this is from memory.  I went to my bookmarks to double check facts
and to get links to post, but for the most part, the sites with
information (which might not always be totally accurate) come and go too
quickly.

One site that seems sorta stable (but they provide no documentation) is
ps2dev.sourceforge.net.  Maybe someday they will offer docs.  They do
offer GCC and binutils for the EE and GE, as well as a fairly large
message board.

Since I can't afford a PS2, I want to learn to program my PSX.  I have the
serial cable, but I still need to get a Gameshark or Action Replay ($50) 
to allow loading new memory cores into the PSX ram.  Using that method,
games are limited to what can fit into memory (BTW, ridge racer, any given
level for that game, everything fits in ram).  The other option seems to
be to burn a new CD for each new revision of the game (which requires that
the  PSX be chipped, another $30) to test it. 

Currently, you can use C/C++, but there are no libraries, so you have to
write your own rendering engine from scratch, and do all hardware calls in
inlined assembly.
 
> `Spectacular' in this case simply means Full-screen, textured polys
> everywhere; Someone who did the math of this reckoned on 8-12meg for the
> geometery, and textures used per second, and 8-12meg doesn't fit in 4meg
> anyway you try.
> 
> Yet again, lack of cache, lack of I/O bandwidth; damn.
 
Perhaps.  But, this is a game machine, not a general purpose machine, so
we can't really say if it was enough until at least the second generation
of titles come out for the system.  By then people may have found a better
way to get the data to the GE.

--
Joshua Boyd