Nice! That's about like saying the display is limited to 160x160 because there are 52 wednesdays in 2003.
Not that I'm bitter about trying to use large datasets you understand :) >The 64K limitation I think is an arbitrary choice. If I recall >correctly, the chunk header allows up to 16M chunks, but they limit it >to 64K because the hotsync protocol only supports up to 64K record >sizes. Regards, Paul Johnson Applewood House www.applewoodhouse.com ----- Original Message ----- From: "Dave Carrigan" <[EMAIL PROTECTED]> To: "Palm Developer Forum" <[EMAIL PROTECTED]> Sent: Wednesday, August 13, 2003 10:29 PM Subject: Re: new and delete in Palm > On Wed, Aug 13, 2003 at 07:42:06PM -0000, drvirens wrote: > > > Dave, would you please take this opportunity and let us know furhter > > in this direction ? I have read somewhere that palm devices dont have > > any MMU. > > > > Let me keep it in this way please...My understadning is that Palm OS > > does not have any virtual memory...so its all segment/chunk oriented > > stuff. Does that the reason why any resource in Palm cannt be larger > > than 64K ? And then....cannt I hide the physical addresses behind the > > handles ? I thought a handle is really a pointer to pointer. I > > particularly wanna know more on how does the system make up for lack > > of a typical MMU ? > > The Dragonball processor doesn't have a MMU, but the existence or lack > of a MMU is not really related to how the PalmOS memory manager > works. Grossly simplified, an MMU is used to map a memory address to > some other address. This is useful in a multitasking OS so that each > process thinks that its memory starts at address 0. The MMU takes care > of mapping the process' virtual address to a real physical address. > > At a higher level, you still need something to manage the memory space > so that when an app calls malloc, or MemHandleNew, or whatever > (including indirect calls through the new operator), the app gets > something, and when the app frees up the memory (via free, > MemHandleFree, delete, etc.), the space is again marked as free. This is > also a called a memory manager, but has nothing to do with the MMU. > > A memory chunk is just an arbitrary name that the PalmOS developers gave > to a piece of memory that is managed by the PalmOS memory manager. Every > OS call that allocates memory (MemPtrNew, MemHandleNew, MemHandleResize, > DmNewRecord, DmResizeRecord, etc.) will eventually get a chunk that the > memory manager has decided it can have. > > The 64K limitation I think is an arbitrary choice. If I recall > correctly, the chunk header allows up to 16M chunks, but they limit it > to 64K because the hotsync protocol only supports up to 64K record > sizes. > > -- > Dave Carrigan > Seattle, WA, USA > [EMAIL PROTECTED] | http://www.rudedog.org/ | ICQ:161669680 > UNIX-Apache-Perl-Linux-Firewalls-LDAP-C-C++-DNS-PalmOS-PostgreSQL-MySQL > > Dave is currently listening to Elvis Costello - No Dancing (My Aim Is True) > > -- > For information on using the Palm Developer Forums, or to unsubscribe, please see http://www.palmos.com/dev/support/forums/ > -- For information on using the Palm Developer Forums, or to unsubscribe, please see http://www.palmos.com/dev/support/forums/
