One of the improvements made to next-generation consoles is how much memory is available for games and the operating system. According to documentation shown to Digital Foundry, 3.5 of the PlayStation 4’s 8GB GDDR5 memory is reserved for the operating system, which leaves approximately 4.5GB for games. Further sources are now saying that there is an additional 1GB of “flexible memory” that could be reclaimed from the OS reserve, if it is available. That would give a total of 5.5GB to game code.
Internal documents from Sony guarantee that 4.5GB of memory will be available to developers and is likely what most of the launch titles will be using. The Killzone: Shadow Fall demo alone took 4.6GB of memory. The additional “flexible memory” can be requested by developers to enhance game elements, but the background OS must be able to spare it.
Developer kits for PlayStation 4 currently have an option in the debug settings called “Game Memory Budget Mode” that allows two options: normal and large. For the normal mode, the guaranteed baseline 4.5GB of memory will be used for games. The large mode allows for 5.25GB of memory, but the documentation states that the extra RAM is only available for application development. The PlayStation 4’s operating system reservation is similar to the Xbox One’s 3GB allocation, where previous documentation only mentioned a 512MB reservation. Both next-generation consoles will launch with 8GB of unified memory, but with a much less amount available to developers.
A large difference between Sony and Microsoft’s OS allocation could be seen in future plans for the reserved RAM. Microsoft engineers chose the 3GB to allow for evolvement over ten-years, as it is difficult to add features if the RAM is reduced from where it began. Sony’s approach might be more flexible as the current allocation between the CPU cores and memory could be reduced once the OS is complete and then streamlined. There is no guarantee, but Sony is leaving the door open for the opportunity and they have experience in reducing the memory, as they did with the PlayStation 3.
Where Microsoft has already shown us what the Xbox One is fully capable of, Sony has yet to fully reveal what the PlayStation 4 has available beyond its impressive gaming functions. Expect more news closer to the fall release.
