|
Well, 400mhz is the fastest PXA-250 part available. There is another chip based on the same XScale core, the 80200 which has a 733-mhz SKU. I believe that one can run higher than that as well.
In the case of XScale PDA's, the main problem is the low performance memory. Its basically the same as what you would find on a strongarm based PDA, so at 400mhz you're usually just stalling 2x more cycles than you were at 200mhz for data, and not getting much new stuff done.
The key to fixing that is of course faster and better memory on the PDA's. But writing code in such a way as it makes the XScale predict what memory it needs, and also not need to fetch new things as often, can help a tremendous amount. Currently PocketPC2002 is completely unoptimized for the XScale. Even the current Axim X5, with its PXA250, could scream a lot faster if the OS and software running on it was designed to take advantage of its cache algorithms, branch prediction, and pipeline length better.
Just take a look at those new PalmOS5 XScale based pda's, like the Sony Clie NX70, they are extremely fast with a 200mhz version of whats in the Axim.
|