What processor or processors do the iPhone models use?

Officially, Apple provided no information regarding the processor and other internal components of the original iPhone, the iPhone 3G, or the iPhone 3GS simply stating that the iPhone is a "closed platform."

For the iPhone 4, Apple originally mentioned that the device was powered by its own A4 processor of an unspecified clockspeed, and still does in some marketing materials, but the company later apparently scrubbed the processor information altogether from official technical specs.

However, for each iPhone model, third-parties have used hardware disassembly, software probing, and technical analysis to determine -- or at least speculate regarding -- the processor that each device uses.

When the original iPhone shipped on June 29, 2007 iFixit disassembled it and learned that the primary processor is an Apple branded Samsung ARM 11 processor running at 412 MHz. Although there was some later speculation that the primary processor might have been provided by Marvell instead of Samsung, Marvell provides the chip for 802.11b/g wireless networking, but not the primary processor.

For the iPhone 3G, iFixit and TechOnline collaborated to not only disassemble the device and confirm that like the original it also is powered by an Apple branded Samsung ARM 11 processor running at 412 MHz, but to go a step further and identify and label an exhaustive number of chips used in the iPhone.

Third-party teardowns from iFixit and RapidRepair -- as well as an analysis from AnandTech -- revealed that the iPhone 3GS has a significantly faster 600 MHz Samsung ARM Cortex A8 processor and a PowerVR SGX graphics processor.

For the iPhone 4, disassembly did not provide any precise details regarding the clockspeed of the Apple-branded "A4" processor and software probing with the Geekbench benchmark only spit out an unhelpful and obviously untrue "0.00 Hz."

However, based on in-depth analysis from both ArsTechnica and AnandTech, two highly reliable sources, and speed tests, it appears that the iPhone 4 is powered by an A4 processor of variable clockspeed that typically runs around 750 MHz to 800 MHz.

Ultimately, most users probably don't need to know or even care to know about processor details for the iPhone models, but for those who do, it is hoped that this variety of methods to evaluate clockspeeds and internal components is interesting nevertheless.