The good folks at iFixithave partnered up with the reverse-engineering gurus at Chipworks to give us an inside view of Apple’s A4 processors as used in the iPad.
We now get to see Apple’s A4 CPU, X-rayed and uncovered.
There are some interesting highlights uncovered from this investigation:
The A4 package is composed of three layers: two layers of RAM (Samsung K4X1G323PE), and one layer containing the actual microprocessor.
This Package-on-Package construction allows Apple to source the RAM from any manufacturer they want. While Apple is sourcing the RAM from Samsung now, this could be changed.
The A4 processor is a single-core CPU, making it either an ARM Cortex A8 or a single-core variant of the A9. Most likely, it’s an A8.
- The two RAM layers each offer 128MB of memory, for a total of 256MB.
- The A4 is quite similar to the Samsung processor Apple uses in the iPhone.
- There are no markings on the CPU die, except on the Samsung DRAM.
Software benchmarks indicate that the A4 has the same PowerVR SGX 535 GPU as is present on the iPhone 3GS, but iFixit/Chipworks couldn’t verify this via hardware analysis. However, if the iPad’s graphics is powered by this GPU, graphics performance on the iPad is fairly poor relative to the screen size.
Other manufacturer’s who supplied parts for the iPad include:
- Linear Technologies
- ST Micro
- Cirrus Logic
- Texas Instruments
Great work iFixit!