Wonder what went into Apple's A4 CPU chip? The folks at iFixIt did. So they hired Chipworks (who specialize in reverse-engineering semiconductors) to perform a "teardown" of the A4. Straight from the desk of Kyle Wiens (iFixit CEO), here are the results so far:
- The A4 package has three layers: two layers of
RAM (Samsung K4X1G323PE), and one layer containing the actual microprocessor.
- This Package-on-Package construction gives Apple the flexibility to source
the RAM from any manufacturer they want‚Äîthey're not locked into Samsung.
- It's clear from both hardware and software that this is a single core
processor, so it must be the ARM Cortex A8, and NOT the rumored multicore A9.
- We don't expect to find any markings from PA Semi, Apple's recent
acquisition, but it's safe to assume they played a major role in designing this
- Every iPhone processor that we have dissected has had a Samsung part number
on the processor die. We have not found any such Samsung markings on the A4
(outside of the DRAM), perhaps the clearest sign to date that Apple is now in
firm control of their semiconductor design.
- Software benchmarks indicate that the A4 has the same PowerVR SGX 535 GPU as
the iPhone 3GS, but verifying this via hardware analysis is quite difficult. If
this is true, and it likely is, graphics performance on the iPad is fairly poor
relative to the screen size.
- There's nothing revolutionary here. In fact, 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.
We also identified several more manufacturers, including Linear Technologies,
Intersil, ST Micro, NXP, Cirrus Logic, Texas Instruments, and Broadcom. More
information on these parts is toward the end of the teardown.
Chipworks lab is still running full-tilt
analyzing the iPad, and they will be updating their site as they discover more: http://www.chipworks.com/Apple-iPAD-Teardown.aspx