At the time Macs started using x86 cores, an alternative to stay PowerPC was to use P.A. Semiconductor’s chip. At the time (2005), it would have been a risky move as P.A. Semiconductor didn’t yet have working silicon. Today however, Apple bought P.A. Semiconductor.
A Desktop Part
What’s interesting is that P.A. Semiconductor’s part, the PA6T, is a desktop part, not something that would fit into an I-Phone.
Wattage: The IPhone’s CPU uses quarter of a watt (it’s either a Samsung S3C6400 or a close derivative). The PA6T uses between 5 and 13 watts, and in the worst case 25W. While this is lower than an Intel desktop chip, it would take too large a battery to fit in a phone.
Memory Bus: The PA6T has two CPUs, each with its own DDR2 bus. That’s a lot of pins, and a lot of memory chips — not something that fits into a phone.
I/O: 8 PCIe controllers, 2×10Gb ethernet controllers, 4×1Gb ethernet controllers. None of this is needed by a phone.
CPU: Two 2GHz PPCs for the 5-13 Watt Core… Apparently future versions will run at 2.5 Ghz, and provide up to 8 cores on a die. Again overkill for a phone.
Although it’s possible that P.A. Semiconductor has another IPhone specific chip in the works, my guess is that the next MacBook Air will use this part. The MacBook Air uses a 20W part, and a 37W hour battery. As a rough calculation, 17W for the system, 20W for the CPU becomes 22W with a 5W CPU, and 20W for a system with a solid state drive. That gives you almost 10 hours of battery life.
This is another step in Apple’s strategy of owning the whole system, letting it chart its own course, although I expect it to continue using commodity x86 chips for lower end systems. For developers, it means we’ll be making FAT binaries for some time yet, even if it does mean more work.