http://www.giantbomb.com/forums/xbox-one-8450/why-does-the-xbox-one-have-a-hypervisor-and-what-i-1437760/

this is a good read on what it should be thats why people said it was lock 3gb dont make sense.   they really should think.  hell they should went with 12 gb

I understand that but it's not PC here.

If you say that devs can use 6GB of RAM... every game have to be 6GB of RAM available for games... so because that you need to reserve that amount of RAM and no other process can use it even if some games didn't use it.

Now looking for the other side... if you are not playing games... no problem in the App OS use more RAM.

This is why I choose Microsoft. They bring greatness to the next generation.

why ??? they could easily lock out resources at 6GB while the game is using 6GB and once again I don't know what you would be doing while gaming on console that would require 3gb of ram for apps when you are ingame..... it's not like they gonna have a adobe photoshop app running photo processing in the background while you play forza.....

keep in mind they went with ddr3 which is great at multitasking not only that.  

"The whole point behind everything above is to accurately express what resources are available to games. We've all seen the information stating that games are provided with 5 gigabytes of memory, 6 of the CPU cores, and supposedly 90% of the CPU cycles. That's going up against the PS4's 8 gigabytes, and a similar processor. Granted, the memory on the PS4 has almost twice the bandwidth, but there are other pieces in the Xbox One that make up for it. Still sounds like a losing hardware battle.

Here's the reality though. We have 8 gigabytes of memory. 5 of which are untouchable and only for games. A developer can always expect at the very least to have those 5 gigabytes. Let's assume that the hypervisor on this thing takes up half a gig of memory. That leaves 2.5 gigabytes available to the Windows kernel. It's not dedicated, but it has access to that 2.5. That doesn't mean your apps will always consume 5/16th of your Xbox One's memory.

The beauty of a hypervisor is we can shut off or suspend operating systems without any effect to others on that same machine. Got a game that needs to load up 6 gigabytes into memory? That's fine - the apps side won't even get in the way. How about 7 gigabytes? I think that's kind of outlandish but let's just suppose. If apps can't run within that last half gig of memory we can just suspend the whole thing and give the whole 7.5 gigabytes to the game."

agreed but once again I demand to see what apps would eat up more than 1 gb on XB1 consoles ????? certainly not Skype, not the NFL app or most of the other apps.... and to that I demand to see what console game will need more than 5gb to run.... we are years away to hit limitation on both side by then enough tweaks will have been added to the XB1....

There is no difference between DDR3 and GDDR5 for Multitasking... inclusive the AMD APUs didn't have benefices over low latencies and even if have the difference is less than 2ns for DDR3 over GDDR3... that a thing that I don't understand why people thinks DDR3 is better for multitasking than GDDR5.

MS just don't used GDDR5 because at the time 8GB was impossible... Sony used 4GB and have lucky because 8GB was possible early this year (Samsung and Hunix launched for mass productions the 4Gbps modules).

And again the memory is reserved for games and there is no sense in Hypervisor make dinamic allocation of RAM while running a game.

Except Windows 8 on the PC is not the same as a console OS. 

The one OS that will be closest to Windows 8 is the Apps OS, but it's still not a full-blow installation of the OS.  The Xbox OS is an updated version of the OS previously used with the Xbox 360.  The HyperVisor OS provides the core functionality and the basic UI, but none of the application or gaming features.  The OS most likely to need 1GB would be the HyperVisor but even that is a stretch. 

That said, even Windows 8 will run in 512MB of RAM, it's just the recommended minimum for reasonable performance is 1GB.  Windows Vista Ultimate with the Aero UI was recommended for 1GB of RAM, yet I ran that perfectly fine on a system with 512MB of RAM.

When a Game OS goes full screen, the App OS goes into stand-by.  

Microsoft may be saying, you have a guaranteed 5GB of memory, but that doesn't mean games won't have more available. 

If you were Microsoft, which would you rather limit.  A game or an application?  I'm guessing they would rather limit the application.  Applications won't be written in C or C++, they'll be written in C# or Visual Basic.Net.  Therefore, there won't be any specific memory reference, instead programmers will allow .Net to manage the memory.  If there isn't enough physical memory, the OS will use a disk cache in order to store code that isn't currently in use.  That way, the application has physical memory in order to operate the application.  This is how Windows has functioned since Windows 3.x.

The Games OS will allow for C++ or .Net code.  With C++ developers do make specific memory references, however that doesn't mean they can't make a memory reference beyond a certain address.  They can, as a part of a routine, determine if there is anything written to that memory address, and if not write to that memory reference.  If that memory address isn't available then go into a different routine to make memory available.

Software doesn't just consume X amount of memory.  The memory usage of any application is fluid, be it a game or some other type of application.  So, yes I'm sure Microsoft, especially for the first round of games, is offering developers memory guidelines so that the initial games don't run into any problems.  That said, I can't see an application requiring almost 1.5GB of memory even if the HyperVisor OS is 512MB or the Apps OS is 1GB.  1.5GB for an application is HUGE!  The only apps that I know of that would consume that much, other than a game, is a high-end video editor and a CAD/CAM application.  I doubt you're going to run Sony Vegas or some other high-end video editing program on the Xbox One, nor do I think you're going to run AutoCAD on the console either.

About the App OS I agree... can be dynimic but the Game OS lke you said will kill the advantage of console optimizations that is a fixed hardware.

You don't need to deal with memory management in consoles games... so your code can run fast and without issues.

If MS said they will reserve xGB for games then the devs will works with that fixed number... not more than that... always using fixed amount memory of memory.