We all know that the PlayStation 4 will be packed with 8GB of GDDR5 RAM, but Sony has yet to officially confirm how that RAM will be split between games and the Operating System.
Digital Foundry claims “a well-placed development source” provided them with current PlayStation 4 documentation that shows that there will be 4.5GB available to developers. ‘Further sources’ suggest that an additional 1GB of “flexible memory” may be reclaimed from the OS reservation, based on availability.
4.5GB is already what the Killzone: Shadow Fall demo used, and, if the rumor is true, will be what most launch titles will use. But the extra gig can be requested by developers to boost certain elements of the game, and Sony may allow it if the background OS can spare it. However “incorporating this isn’t trivial”, with possibly only first-party developers targeting its usage.
The rumor that the PS4′s OS RAM reservation of 3.5GB is similar to (and even than) the Xbox One’s 3GB reservation differs from previous reports of only 512MB, but they existed back when the PS4 was set to have only 4GB GDDR5 overall. DF’s sources say that this extra RAM allocation will allow for seamless switching between apps and games, akin to what Microsoft demonstrated with the One.
DF also says that Microsoft plans to keep the 3GB allocation to allow for OS changes over 10 years, but that Sony may be open to reducing it once the operating system is complete and has been streamlined.