Smartphone Memory Configuration

Question

Smart-phones have built in ROM and RAM separately. Also a few phones has virtual memory support too. I would like to know what these memories are basically used for. I understand that RAM is available to user processes. But why do they have a big chunk of ROM?

E.g. The wiki page for Droid Incredible says

• 512 MB DDR RAM
• 1 GB ROM (748 MB free to user) - what's this free to user?
• plus 8 GB moviNAND - typically used for data storage

Answer 1

ROM is a bit of a misnomer, here. It's the place where users can store apps. It's "read only" only in the sense that YOUR code can't write to it. (This is likely for security reasons, to prevent viruses, etc., from overwriting your code.) So the OS can write to it, to store the apps there, but not your code.

The 8G is the data area available for your music, pictures or your code to write data.