On Feb 17, 2005, at 9:29 PM, Neil Rhodes wrote:

> I worked on a Squeak port to Palm OS about 1999 (coming at it as a 
> very experienced Palm OS programmer and a newbie Squeaker), and am 
> very familiar with the issues involved:
>
> The Palm OS is split into the dynamic heap and the storage heap (which 
> is write-protected, and requires an API to write). It isn't practical 
> to run an image directly from the storage heap.  Either every write to 
> the image requires an API call (DmWrite), or you've got to use the 
> undocumented (and dangerous) MemSemaphoreReserve, which turns off 
> write-protection.
>
> At the time I was working, there were no devices with a large enough 
> dynamic heap to hold an image.  I looked at two different ways of 
> running the image from the storage heap:
> 	Storing the image in separate 64K chunks, and using a macro to 
> determine the actual memory address to use to read from/write to
> 	Storing the image in a large storage heap chunk (allocated using 
> FtrPtrNew).  When the app opened, it'd copy the image from the 
> database to the large chunk. On close, it'd write it back out.
>
> Another alternative to storing the image would be as a file on an SD 
> card.  You use VFS calls to open/close/read/write.
>
> If I were approaching it today, I'd target the couple of devices that 
> have a large enough dynamic heap to be useful:
> 	
>  Tungsten C   12MB 
>  Tungsten T3  11MB 
>  Zire 72      5MB   
>
> I think the Tungsten C or T3 would be a very workable Squeak device.
>
>
> When the app opened, I'd allocate a large dynamic memory chunk (using 
> MemChunkNew with the memNewChunkFlagAllowLarge flag to allow a larger 
> than 64K allocation).
>

So does Palm OS 5 still enforce these types of memory limits and 
segregation now that the high end models are running on XScale 
processors? I had *hoped* that they would take advantage of some of the 
potential of the new hardware platform, but I realize that they would 
have issues with backward compatibility if they did that, although they 
could probably do some emulation.

Brian