[Galaxy S I9000 General] tony604:
SoC: System on a chip

System on a chip (application processor) means exactly what it says. It is a chip containing all the components of a typical computer system on a single chip. CPU, video chip, memory controller, etc

ARM is a company that designs computer chips for the mobile platform. ARM does not manufacture chips. They create the instructions sets, and design application cores (like the Cortex A8) based on their instruction sets. They license either their instruction sets or their application core designs based on their instructions sets. Current high end smartphones use chips based on their ARMv7 instruction set.

We've all heard of snapdragon, hummingbird, cortex a8, and maybe even OMAP3. All these chips use the same ARMv7 instruction set.

Qualcomm Snapdragon: Qualcomm licensed the ARMv7 instruction from ARM to produce their Scorpion core, which is used in their snapdragon SoC. Qualcomm spent considerable time (1.5 years I think) and money to develop the Scoroion core used in the Snapdragon. The Scorpion core is similar to the cortex A8 core in that they use the same ARMv7 instruction set, but the Scorpion core has design elements that give it superior performance over the Cortex A8.

Cortex A8: This is a core designed by ARM based on their ARMv7 instruction set. Unlike Qualcomm, some companies such as Samsung opt to license the core design rather than license the instruction set and spend the resources to come up with their own core design based on the ARMv7 instruction. So they end up making their own SoC using ARM's core design saving the time and energy to develop their own core. The upside is their chips cost less and they can bring these chips to market faster. The downside is they have no control over the core design (except maybe some minor tweaking), so a company like Qualcomm can bring a competing chip to market that will offer better performance.

Samsung Hummingbird: This is a SoC chip designed by Samsung using ARM's Cortex A8 core. The Scorpion core used in the Snapdragon SoC offers better performance, but the PowerVR SGX 540 GPU in the Hummingbird performs better than the AMD Z430 (aka Adreno 200) GPU.

Apple A4: From what I've read, this SoC is almost identical to the Hummingbird SoC. This chip is also manufactured by Samsung. There were a few minor tweaks Apple used in their A4 chip, so the A4 and Hummingbird are not exactly identical but are fundamentally the same chip.

Texas Instrument OMAP3: Like the Hummingbird, TI licensed the Cortex A8 core design from ARM and incorporated it into their OMAP3 SoC. The OMAP3 uses the PowerVR SGX 530 GPU and is found in smartphones such as the Motorola Droid, Palm Pre and Samsung Omnia HD.

I hope this sheds some light into some of the confusion I've seen in these types of snapdragon vs hummingbird topics. As you can see, when talking about the hummingbird and snapdragon, one chip may preform better in some areas, and the other chip may preform better in other areas. Of course software will also have an impact to end user experience. One other thing to take into account is the manufacturing process. The Snapdragon QSD8650 found in phones like the Nexus One use the 65nm process, vs the Hummingbird's 45nm process. Despite this, the Snapdragon's Scorpion core is still faster, although the Hummingbird will consume less energy and produce less heat. More recent phones such as the Desire HD feature an updated 45nm Snapdragon MSM8255 processor along with the Adreno 205 GPU. ARM's next generation application core is the Cortex A9 which will support dual core configurations. The RIM Playbook will probably be the first device to use the new Cortex A9 (dual core 1Ghz!)