iPhone 1st Generation and iPhone 3G shipped with 128 MB of RAM, however iPhone 3G S shipped with 256 MB. I have no idea why Apple still hiding the information about iPhone’s hardware specification. If you have installed the SBSettings from Cydia and turn on the Free Memory Status Bar, you may able to see how many free memory of the iPhone have. My iPhone 1st Generation free memory at range 20 MB – 30 MB. So how to boost it? There was already an application called iPhoneVM which is available on Cydia. iPhoneVM able to boost the free memory of your RAM up to 80 MB! Too good to be true, there is problem, the iPhone often lagging even when just typing an SMS but it’s pretty good enough when you playing a game. Here’s the way to set it up:

1. On Cydia add new source http://repo.beyouriphone.com/
2. Once done, navigate the BeYouriPhone source and search for iPhoneVM then install it.
3. Reboot the iPhone after the installation finished.
4. Voila the iPhone have more free memory now!

Update (November 18, 2009):
Also available iPhone VM 2 which is providing similar functionality. The differences are iPhone VM 2 creates a dynamic swap file rather than creates a static swap file which far more stable than iPhone VM. You can find iPhone VM 2 from BeYouriPhone’s repository.