Difference Between Apple A4 and A5 Processors

Apple A4 vs A5 Processors | Apple A5 vs A4 Speed, Performance
 

Apple A4 and A5 are Apple’s latest System on Chips (SoC) designed targeting their hand held devices. In a Layperson’s term, a SoC is a computer on a single IC (Integrated Circuit, aka chip). Technically, a SoC is an IC that integrates typical components on a computer (such as microprocessor, memory, input/output) and other systems that cater electronic and radio functionalities. Apple A4 and A5 use an IC packaging technique known as Package-on-Package (PoP), where the logic components are packed vertically apart from their typical horizontal packaging.

The two major components of A4 and A5 SoCs are their ARM based CPU (Central Processing Unit, aka processor) and PowerVR based GPU (Graphics Processing Unit). Both A4 and A5 are based on ARM’s v7 ISA (instruction set architecture, the one that is used as the starting place of designing a processor). The CPU and the GPU in both A4 and A5 are built in the semiconductor technology known as 45nm. Although Apple designed them, Samsung manufactured them on the request made by Apple.

Apple A4

A4 was first commercially produced in March 2010, and Apple used it for their Apple iPad, the first tablet PC marketed by Apple. Following the deployment in iPad, Apple A4 was later deployed in iPhone4 and iPod touch 4G. A4’s CPU is designed by Apple based on ARM Cortex-A8 processor (that uses ARM v7 ISA), and its GPU is based on PowerVR’s SGX535 graphics processor. The CPU in A4 is clocked at a speed of 1GHz, and the GPU’s clock speed is a mystery (was not revealed by Apple). A4 had both L1 cache (instruction and data) and L2 cache hierarchies, and it allowed to pack DDR2 memory blocks (although it did not contain memory module packed originally). The sizes of memory packaged varied among different devices such as 2x128MB in iPad, 2x256MB in iPhone4.

Apple A5

A5 was first sold in March 2011, when Apple released its latest tablet, iPad2. Later Apple’s recent iPhone clone, iPhone 4S was released equipped with Apple A5. As opposed to A4, A5 had dual cores in its both CPU and GPU. Therefore, technically Apple A5 is not just a SoC, but a MPSoC (Multi Processor System on Chip). A5’s dual core CPU is based on ARM Cotex-A9 processor (that uses the same ARM v7 ISA that is used by Apple A4), and its dual core GPU is based on PowerVR SGX543MP2 graphics processor. A5’s CPU is typically clocked at 1GHz (the clocking uses frequency scaling; therefore, the clock speed can change from 800MHz to 1GHz, based on the load, targeting power saving), and its GPU is clocked at 200MHz. Although, A5 has similar L1 cache memories to that of A4, its L2 cache size is double the size of A4. A5 comes with a 512MB DDR2 memory package that is typically clocked at 533MHz.