EE Times has taken an even closer look at the ARM-based processors used inside the A4 chip and the Samsung S5PC110A01, following recent revelations that both use CPU cores which are very like each other -- and the findings reveal both chips are very similar, but different.
Both processors are based on ARM’s Cortex-A8 CPU core, but both companies have added some of their own magic alongside the basic core offering, with Apple borrowing heavily from Intrinsity, rather than the once rumoured PA Semi in its design. Apple has also taken a few ideas from Samsung.
UBM TechInsights published side-by-side die images of the Samsung S5PC110 and the A4. EETimes goes one step further, publishing high-resolution micro-photography of the A4 architecture using infra-red illumination and image acquisition through the backside of the intact die.
The way the A4 processors ARM core is arranged strongly suggests use of Intrinsity technologies within the design, the report informs. As the image shows us, the ARM Core is in a different position on both the Apple and Samsung SoCs.
The report also tells us that while the Samsung and Apple cores are similar, as System on Chips (SoC’s) they diverge, with differing degrees of customization at block level.
In particular, these reveal that the Apple chip has seen all unneeded elements of the generic ARM reference design removed, reducing chip complexity, size and cost. In other words, Apple’s A4 processor is a tailored version of the standard Cortex-A8 that differs from the iteration issued by Samsung.
We find this comment within the article quite revealing, as it confirms what some have been thinking that Apple has designed the processor within a much wider context -- it isn’t just about what the processor is capable of, its 1GHz speed at low power and so on, it is also about how the processor has been tailored specifically to be the most efficient mobile processor for Apple’s iOS itself.
“A full analysis requires thinking about the chip in the context of the whole device, including the OS, which is known to be quite efficient. Consideration should also be given to the broader business and IP implications of the possible expanding role of circuit design in Apple's strategy and the arguments for introducing a new product with incremental advances in technology rather than wholesale design changes,” says EE Times.
Here’s an interesting account of Apple’s previous purchases of processor people.