I notice in the recently released diagrams that there is an extra 8GB (Same as the original Xbox) tucked in by the South Bridge of the Xbox One.  (Where did it come from?) Incidentally the on die storage of the chip is 47MB which is @70% of the RAM of the original Xbox.  It's like there is an entire tiny little hard working Xbox inside the Xbox One.

One of the upgrades I really wanted them to included in the Next Gen Consoles was a solid state drive.  Some of the advantages to these are no moving parts, and they are super fast.  The downside is they are expensive, so what people do is a compromise have the operating system on a Solid State Drive and use a regular Hard Drive for most storage.  This give you quick responses to the stuff you use most and plenty of storage for everything else. I was disappointed when it looked as if both new consoles dd not have this feature.

Looks like someone snuck in a little extra 8GB of memory.

If you look at the schematic here.  Notice on the bottom left, past the Bluray and the 500GB Hard Drive, there is a little box saying 8GB Flash.  I haven't found any conformation yet that this is being used as a Solid State Drive, but seems to be a reasonable assumption.  What else would it be?  So there is an extra 8GB of rather fast memory on board.  Sounds like some rumors we heard before might have a factual component to them.

So with 8GB of RAM on board and another 8GB on a flash drive.  Since 8+8 = 16 and sometimes rumors are not properly overheard. Do you think this might be where that 16GB of RAM came from?  Seems like the most likely case to me.  And should help greatly with system performance. 

The flash there is still a mystery to me and its purpose is unknows to almost all, aside from speculations. It could serve for the (crappy) BD-Live or something... But then emmc 4.5 would be overkill. It could also be used for pausing/resuming bluray-playback, bookmarks on blurays and all this things but I think until launch we will know!

I wouldn't call it a SSD, as SSDs usually have complex controllers. This is an eMMC 4.5 device which uses a standardized controller (see: http://www.jedec.org/news/pressreleases/jedec-announces-publication-e-mmc-standard-update-v45 ). There is no real criterion at what point a flash based device starts to be a SSD, but imho at least 2 flash chips (operating in parallel) are required.

It's most likely to store the Firmware/operating system or at least some important stuff of it. It was handled the same way on PS3 and 360. The consoles would be a lot slower if everything of the firmware was stored on a hard drive.

I came to this because of where it is located.

I agree, that is why I'm not calling it that.  But what else might it be doing around in there? 

It doesn't say how many chips, just that it is (an unexpected) 8GB Flash.

Possible.

But 8 GB is quite large. I would understand it if the Xbox One had a swappable HDD, but as it is I see no real reason to store such a large part of the OS on flash.

At the moment I would guess that the 8GB are used to flush the entire data in the RAM to it when the console goes into standby (this doesn't have to be instantaneous, but can take around a minute in the background).

I think they just went with 8 GB to future proof the console. No need to copy the RAM as long as the system is in stand-by. The RAM doesn't need much power to keep whatever is saved atm. It works that way on laptops too. 

Well, 8GB and 16GB are the common flash chip sizes today. 4GB aren't much cheaper any more (I don't know if that's also true for eMMC devices). So maybe you are right. 

Actually, you actually can not take the hard drive out by design of the Xbox One.

You could be right, but wouldn't that burn it out rather quickly?  I was also thinking it could be part of the game DVR feature - but the PS4 has a similar feature and doesn't use it.

I was thinking one could put the OS on there for speed.  But we really have to know how it is being accessed and thus the speed.