"DIAMOND JEFF" <[EMAIL PROTECTED]> wrote in message
news:37921@palm-dev-forum...
>
> I'm sure Palm has already worked all this out, but in case any of the
> results are surprising, I thought I'd ask so I can begin preparations.
>
> My impression of the standard ARM core (and maybe Palm has found a
> variant) is that:
>
> (1) Big Endian mode only has second class support, i.e., swap on
> load/store
> (2) 32-bit word accesses must occur on 32-bit aligned boundaries.
>
> Obviously, if either of these points remains, the implications are
> staggering: all applications need to be recompiled, all pre-existing
> databases need to be migrated, and all programs must be debugged for
> every instance of the logical equivalent of a union.
They both will be in the ARM Palm -- At PalmSource 2000, we were told that
1) OS 5 will do some structure conversion returning proxy structures to 68K
code, but in most cases, you will be required to go through the API
functions to read and write to system structures.
2) An ARM Palm will be little endian.
3) 32-bit alignment will also be an issue -- the system structs will be
rearranged to not have any unnatural boundaries. Also, 68K code running
emulated wouldn't have alignment issues, since those can be fixed at
emulation time. New code that you build for both 68K and ARM should respect
32-bit alignment.
> Also, while this would have a slight hit on cost, I certainly hope Palm
> is going for a 32-bit bus to the data and instruction caches and as wide
> a bus as possible from cache to ram. The whole key to getting
> performance at low power is low frequency / high bus width - and you're
> gonna need as much memory bandwidth as possible to feed those high MHz
> ARMs. :) Of course, this is assuming the primary goal of the migration
> effort is for future performance and not merely for better CPU supplies.
Why do you need high MHz ARMs? I've seen plenty of ARM applications where
the clock speed was similar to the current DB clock speed. I once helped
design an ARM system which usually was running at 32KHz (yes, kilohertz). I
think a two primary goals of the ARM move is compatability with cell phone
cores which are predominantly ARM and allowing multiple suppliers of CPU
chips, removing the Motorola monopoly.
--
Ben Combee
Veriprise Wireless <http://www.veriprise.com>
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