With a die size of 165 mm2
, the A5X is approximately 43 mm2
larger than the A5. The 32 mm2
increase in GPU real estate leaves a remaining area of 11 mm2
. That doesn't sound like too much for the A5X, but it is 25 percent of the total A4 die area. So there is additional design here.
I count 15 digital blocks outside of the CPU/GPU combo in the A5X compared to 12 for the A5. Beyond that are what appear to be two arrays on the A5X that are absent in the A5. These “arrays” have been highlighted on a partial A5X die photo. They might be ROM containing microcode.
What's the stuff outside of the CPU and GPU cores? It is a mixed bag.
Mundane stuff like memory bridges, specific interface circuitry, other peripherals and associated overhead make the whole thing operate. Then there are the various IP blocks that may well include the anobit (now Apple) Flash controller. Blocks that likely perform dedicated processing tasks are also seen.
We discussed the possibility of hardware-based encoder blocks in a recent A5 article
The general theme of “extra” area was cited by Microprocessor Report
, which commented that 33 mm2
can not be accounted for. This squares with our earlier estimate of 34 mm2
The extra 11 mm2
in the A5X falls into this group. I think this “unaccounted” area could include circuitry that breathes life into the Jobs comment about "further differentiation."
Now, the A6
With consumers and tear down specialists just now getting their hands on the iPhone 5, we'll await the first die photos.
In them meantime, we must sift through bits of available information about the A(x) processor lineage.
As pointed out in an here
, Apple released little information about the A6 during a Sept. 12 event. It did provide one key piece of information: The A6 is 22 percent smaller than the A5. This works out to a die size of 96 mm2. The reduction in die area is associated with the very likely process shrink from 45 nm to 32 nm. An A5X die area of 165 mm2
and a 41 percent reduction in area works out to 96 mm2
Yes it is the same number, but I think it's a red herring. It's unlikely any interpretation of GPU/CPU cores can be extracted from this number. Again, it's more than simply accounting for the CPU/GPU area. There is some really interesting circuitry outside this combo. Apple is doing more than just rearranging the furniture.