I wandered down the hall to confirm my information...

Actually, Jamey Hicks corrected me: three or four places in the system would
have to be fixed to deal with the cache, and turning on the write back cache
is not likely to be feasible under WinCE until/unless the base system
is changed to deal with it.  The cache code is set by the operating system
image, and not by the bootloader.  So it seems pretty hopeless to
try to do any user space hacking....

So I suspect one is out of luck unless/until one runs Linux on the iPAQ
or until the base WinCE systems are upgrade (if ever).  And getting
a 39xx or 54xx with 255's in them isn't obviously possible.

I (and Jamey) have no idea if we (HP) have plans to release a PXA255
version of the existing iPAQ's or not.  The unit that Jamey has tested
PXA 255's running Linux on was upgraded by PocketPC Tech.  It would
be interesting to try Squeak on it to get some idea of the performance
difference, particularly if someone has ipkg's made up of Squeak.

You'll see future iPAQ's with 255's for sure, of course.
                                 - Jim


--
Jim Gettys
Cambridge Research Laboratory
HP Labs, Hewlett-Packard Company
Jim.Gettys at hp.com