The following is edited from (and translated from) an E-mail I sent
to my sister. My sister claimed that GameCube was said to be an
128-bit system, while I was thinking that since it's a PowerPC system,
it can't possibly do more than 32 bits - and who cares if it can't do
more than that, anyway, I've been a happy user of 32-bit computers for
quite a time now, all of them have been quite good for their
time. Note that I'm not a hardware guy and last time programmed in
Assembler for C64, so this might not be 100% accurate either.)
After some research (consulting Nintendo's specs and the
Wikipedia), The GameCube's PowerPC "Gecko" processor is indeed a
128-bit one, though this isn't for all kinds of oprations.
How many bits a processor has is, these days, not very
relevant. The most important factor when considering the processor
speeds nowadays is the clockspeed measured in megahertz, though even
that isn't comparable between two different kinds of architectures. In
other words, a 1GHz Intel Pentium4 isn't as fast as 1GHz PowerPC or
even a 1GHz AMD
processor, even when
P4 and the
AMD are mostly
compatible with each other.
"Bitness" measures one thing in the processor: How much data the
processor can handle at a time? Specifically, how much data the
processor can handle with a single programming instruction?
The problem is that modern processors don't process all information
in equal sized chunks. The larger chunks you process, the slower it
is, so different kinds of hardware should only be processed at the
precision that is absolutely necessary.
The GameCube processor can handle
- 32-bit integer operations,
- 64-bit decimal operations,
- 128-bit SIMD
operations, that is, processing a large dataset in parallel, or some
other voodoo stuff, please don't ask me for details.
So, GameCube is 128-bit, but only for certain types of
operations. This is, however, better than the competition (see
below).
Most part of the code will use (the 32-bit) integer mathematics
anyway, since it's the fastest to do. But let's not forget
that the processor can do 128-bit operations. Therefore, it's
justified to call the console 128-bit.
On the other hand, we can just say that Nintendo 64 is 64-bit but
only for certain operations. Playstation 2 is 128-bit if you do vector
operations - but not otherwise. Atari Jaguar isn't exactly 64 bit
since it can do 32-bit stuff in two different processors. Well, with
that logic, PS2
isn't 128-bit either, because vector processor unit is
separate. And XBox has an almost ordinary 32-bit Intel processor,
which, due to cost, has been made less powerful than an equivalent
processor found in PC component stores.
Also, what's noticeable: Nobody needs more precise operations
than this. 32 bit integers will take you far, and the program
can, if necessary, simulate a larger number range with programmatic
tricks (hell, people did 64-bit calculations on ye olde Commodore 64,
which clearly couldn't do more than 8 bits itself! And that processor
didn't have any damned decimal operations either!)
So, let's just let the people who wait for the era of "256-bit"
consoles. The technical progress is breathtaking, but the ambition is
restrained by practicality - 64 bit integer operations (and 128-bit
floating point operations, once the
<acronym title="Institute of Electrical and Electronics
Engineers">IEEE invents and standardizes them)
might appear on the popularily used processors in near
future, but no one in their right mind is going to make a processor
that handles 256-bit integer operations! It is more likely that a new
data processing technique using 256 bits at a time (similar to the
SIMD
mentioned above) is invented, added to the processors, thus justifying
to call them 256-bit processors.
Not to even mention the size of the address bus - in other words,
it might be pretty cool to use a computer that can have
1.15*1053 yottabytes of memory - nice how we've run out of
SI prefixes for powers of ten long ago - but no game can require that
kind of memory space. Well, I don't think there's even enough atoms in
this universe to build that kind of memory...
So, what do we learn from this? The marketing people are always
pulling the engineers to the dirt by telling about things that aren't
exactly true - because explaining the whole truth might take some time
and the "masses" wouldn't understand them anyway. Someone ought to
tell the amrketing people that it doesn't matter, they should rather
make sure the games are better than the competition's games =)