iPad's A4 processor uncovered

The good folks at iFixit have 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.
Written by Adrian Kingsley-Hughes, Senior Contributing Editor

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.

Image courtesy of iFixit/Chipworks

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.

Image courtesy of iFixit/Chipworks

  • 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. The primary focus of this design was minimizing power consumption and cost rather then developing a revolutionary new CPU.
  • There are no markings on the CPU die, except on the Samsung DRAM.

Image courtesy of iFixit/Chipworks

  • 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 - Intersil - ST Micro - NXP - Cirrus Logic - Texas Instruments - Broadcom

Great work iFixit!

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