The A5 Processor: Double the Cores, Double the Fun

The iPad 2’s A5 extends and improves on the original A4 with a second core and improved graphics, translating to improved responsiveness and more immersive gaming.

Apple bills the new A5 processor as “it’s fast, times two,” but at the same time, it suggests that the graphics are “up to 9x faster.” Those two very different claims aren’t contradictory. The A5 is a system-on-chip (SoC), so includes both the CPU, the GPU (graphics processor), and even embedded memory. The A5 is most likely a multi-chip module, combining several different semiconductor parts into a single package. Several sources have suggested that, in addition to the GPU and CPU cores, the A5 incorporates 512MB of fast DDR2 memory running at 1066MHz. If so, that’s double the RAM in the current iPad.

More RAM is good because a dual-core CPU’s strength lies in multitasking and multithreading, rather than improving single-task performance. The A5 is likely based on ARM’s Cortex-A9 architecture with each core supporting 64KB of split cache (32KB instruction and 32KB data).

Somehow, it even looks fast!

The A5 CPU is really an evolution of the iPad 1’s CPU. While adding another core will be useful for power users running multiple iOS tasks, the onboard PowerVR SGX 5 series GPU is likely to have a bigger impact on user perceptions. The SGX 5 series offers substantial enhancements over the earlier PowerVR 4 series built into the A4. Since the iPad 2 will make heavy use of video due to the front and rear cameras, improved video performance will certainly be welcome.

The SGX also offers big gains in performance of 3D accelerated apps. Apple’s past reluctance to push into games is history, and the iPad 2 is being touted as an excellent platform for visual gaming. Apple also notes that video editing will be improved, which suggests that both iOS and applications have access to the GPU for not just graphics acceleration, but also for GPU compute tasks. This makes the SGX an equal partner with the dual core ARM-based CPU in the iPad 2 processing equation.

Overall, iPad 2 power users will see smoother video, more robust gaming, and better multitasking performance with the A5 CPU. More sedate users—ones who simply use iPads as email and web browsers—probably won’t see big gains. Still, the A5 looks to be a significant improvement that makes the iPad 2 a true netbook killer.