Originally Posted by stelligent
In fact, it is NOT.
With all due respect, you can't just read Wikipedia or Appleinsider, and believe that's whole story.
Perhaps it's semantics about what a chip is in today's world. Most assuredly, in the semiconductor business, the two *packages* are considered separate entities. Most of the time, they only come together in one of the final steps of manufacturing of the circuit board. Cost savings is not a factor in the sense you imply because the CPU layer and the memory layer are manufactured independently, often by different manufacturers.
All to say, the RAM is NOT part of the CPU and can be easily interchanged. Now, if they are stacked-die packages, then you'd be right because they cannot be interchanged.
With 'CPU', I meant the A5 SoC as a whole, not just the collection of transistors that make up the CPU part, if we start nitpicking about that you could even say the GPU is not 'on the CPU' even though it's pretty clear that if someone says so, he means that the GPU and CPU are the same chip (were chip means: the black square thingy on the iPhone logic board).
So assuming we agree on this loose definition of 'the A5 CPU', which in fact is more than just a CPU, I think you can safely say the RAM is 'on the CPU'. Like I said, in my earlier post, this does not mean Apple couldn't make an A5 CPU with 1 GB of RAM, but surely it's much more cost effective to make ALL of the A5 CPU's exactly the same. Just ebcause you join the RAM package to the CPU package late in the production process, that doesn't mean the CPU package can be used unmodified with any size of RAM package you bolt on top of it. Are you really arguing that it would be trivial and inexpensive to put up seperate production lines for 512 MB and 1 GB versions of the A5?
I didn't get this from Wikipedia by the way, and I believe that over 10 years in the semiconductor industry should be sufficient to judge whether the RAM is 'on the CPU'.