PSP - officially as powerful as PS2*
Anyone fortunate enough to have seen the PSP version of Ridge Racer will know that Sony’s handheld is a quite astonishing piece of hardware. But the arguments rumble on concerning exactly how powerful it is. The fact that most journalists are attempting comparisons with PS2 is indication enough that PSP represents a startling move forward for handheld gaming – at least in terms of visual performance. The question is, how valid or accurate are those comparisons?
Frankly, I don’t know – I’m not a games programmer. So I’ve been chatting to Andy Beveridge, co-founder of SN Systems, the Bristol-based technology company that provides development tools to most of the studios working on PSP titles.
And here’s what he has to say on the debate that’s dividing the nation: PSP vs PS2 - is one more powerful than the other, or is such a comparison impossible? His comments reveal some interesting little snippets about the innards of Sony's new machine...
*although it's more compicated than that as you'll soon found out.
“The main reason there is little comparison info out there is probably that it's a difficult thing to compare. If the two CPUs were identical then clock speed would indeed give you a good comparison of performance. Both CPU's are MIPS family with fairly compatible instruction sets but under-the-hood they are quite differently put together.
eg. It's a bit like comparing an AMD Athlon with a P4 CPU. A 2GHz AMD CPU goes a lot faster than a 2GHz P4 CPU. That presumably is why AMD use XP+ numbers rather than clock speed (eg. an Athlon 2800+ actually has a clock speed of just over 2GHz, not 2.8GHz).
So you can compare clock speeds but that is really only part of the picture. The PSP CPU has a variable clock speed from 1 to 333MHz. It runs at the lower speeds when possible to save power. PS2 CPU runs at 300MHz all the time. PS2 CPU also has an extra boost because sometimes it can run more than one instruction at a time which makes it's CPU a little faster still compared with PSP which can only execute one instruction per clock cycle at best.
But only a fraction of the console's perceived performance is down to the CPU. In the current generation of gaming machines the performance is just as much affected by 3D maths capability and by the graphics core. PS2 has two 150MHz programmable vector units to do the maths - these are quite powerful but they make the PS2 a little complicated to program as it is like programming three computers in one. PSP has one special 3D math coprocessor but it is surprisingly powerful and much easier to program and in many cases faster. The graphics cores of the two machines are also quite different.
So it is difficult to make a straight comparison. I would say that overall most programmers would probably conclude that the PS2 CPU is slightly more powerful if both CPUs are given the same thing to do. That's the killer issue though - the two CPUs typically do not have the same thing to do. One major factor here is the PSP's smaller screen. A PS2 screen at 640 x 480 has 2.3x the area of a PSP screen at 480x272. As a result a typical PS2 games has quite a lot more to draw and so it needs that extra power.
Conclusion? Two programmers could argue all day about which is the more powerful and there is not one clear answer except, 'It depends what they are doing'. However, they are clearly in the same ballpark, which is pretty impressive for a battery operated portable console.”
So there you have it. PSP is as powerful as PS2. But in a different way. Erm, let me read that again...
Posted by Keith Stuart at 11:52 AM
