of this series began a discussion of the differences between PalmOS and Symbian OS. Despite their superficial similarities, programming in Symbian isn't just like programming a Palm PDA. Part 2 takes this discussion even further, covering the areas where these two operating systems really
go in different directions.
If you're thinking about moving to Symbian OS from PalmOS, one of the biggest differences is how Symbian OS handles memory. While both have main memory and permanent storage memory, they use them differently.
Palm OS uses RAM for both main memory, the dynamic area, and permanent storage, the storage area. As you might guess from the names, the dynamic area runs programs while the storage area stores programs and data just as a hard drive would on a PC.
While Palm OS handhelds also use flash memory, a removable expansion card such as a Secure Digital card, MultiMediaCard (MMC), or Memory Stick for permanent storage, they must use some of their RAM for permanent storage of the operating system. The exact amount of RAM used for this purpose depends on which version of Palm OS is in use. Currently, Palm OS accesses only up to 16MBs of RAM. But Version 5.2 brings support for up to 128MBs of RAM.
Figure 1 shows a typical Palm OS device with removable expansion memory and flash memory.
Symbian OS Memory
Symbian OS devices use RAM just as it is used on a PCwith all the main memory available for the operating system and applications. Permanent storage is kept in flash memory and expansion cards like the Nokia 9200 Series' MMC.
As you can see in Figure 2, the, the way RAM is allocated allows you more active, main, memory for your Symbian OS applications than you would have for your Palm OS programs. In addition, Symbian uses all hardware supported RAM to a theatrical maximum of 2GBs.