It's a "software" cache, it's stored in RAM.

I didn't describe anything, and if you still think it's 1080i, then either you didn't understand how it works correctly, or the person who described it to you got it wrong. I posted a link earlier to the game developer's blog where the technique is described in detail: https://www.killzone.com/en_GB...

It doesn't directly come from the previous frame like in an interlaced mode, it's instead generated using information from the 3 previous frames.
Also, the HUD is rendered at full resolution.

It's not. Here's how it works.

It's not 1080i either.

There are 1920 columns in each frame. What's different is how half of those columns are rendered.

Their term is temporal reprojection, which is the most accurate. The scaling term is an incorrect simplification made by the writer. Scaling implies it's a linear tranformation but in this case there's also an element of prediction using the motion buffers.

They are not pixels from the previous frames. They are new pixels generated using pixels and motion vectors from the previous frames.

It's not scaling and it only looks slightly blurry with fast movement, otherwise it look just as if it was rendered at full resolution.

That's arguable. Pretty much all AAA games render some stuff (shadows, particle effects, etc...) at half or quarter resolution. Where do you draw the line between what's native resolution or not?

You're confused. The person I was replying to wasn't talking about Morpheus since it's obviously not on sale.

Sony doesn't have theirs on sale yet, and it's still at least a year away. What you used is probably their old HMD, which isn't a VR headset.

They haven't opensource it. What they did is release documentation for it, and the RPi foundation has hired someone to work on an open source driver.

They do more than just CPU cores. The GPU in this thing, for example, is from ARM.

That's not true. It's playing for me just fine at 60 fps (or rather it's fluctuating between 30 and 50) in Chrome with the Flash player (I've disabled the HTML5 player because it doesn't do hardware acceleration for some reason on my laptop).