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The big mystery behind the recent Apple iPad announcement is the A4 processor that powers this touchscreen, “tablet” PC. What’s in it, and why did Apple design its own system-on-chip (SoC) as opposed to using off-the-shelf hardware? First, I offer some tidbits of information and speculation gleaned from various on-line articles, and secondly, I have a few thoughts about what the A4 tells us about the future of chip design and EDA.
As noted in a Cadence Community blog by Jack Erickson, a tablet PC has some special requirements. It has to be more graphics-intensive than a traditional PC, requiring more CPU horsepower. It also needs longer battery life than a PC, with a smaller and lighter battery. This is hard to do with off-the-shelf hardware.
About all the Apple has publicly said is that the A4 is the “most advanced chip” the company has ever used, and its power efficiency gives the iPad up to 10 hours of battery life. The Apple iPad spec sheet calls it a 1 GHz “custom designed, high-performance, low-power system-on-a-chip.” Apple has IC design expertise from its April 2008 purchase of low-power processor developer PA Semi.
Here’s what a few on-line articles have said:
New York Times
This article notes that Apple has taken a bold step by designing its own processor, but has also taken on extra engineering costs. It notes that several key PA Semi chip engineers have already left Apple. The article also says that some analysts believe Samsung is manufacturing the A4.
Suzanne Deffree’s blog states it is “assumed” that the A4 came out of the acquisition of PA Semi. But a blog comment notes that it takes at least 12-18 months to design, debug and manufacture an SoC like the A4, and that the design was likely underway before the PA Semi people came on board at Apple.
A CNET reporter describes the A4 as an SoC integrating a main processor, a graphics processor, a memory controller, and other functions. The article says the core processor is from ARM, maintaining compatibility with the iPhone.
There’s some interesting history here. The article notes that PA Semi outlined a vision for an SoC PowerPC architecture, called PWRficient, in 2005. The sole member of the family was released in 2007; it ran at 2 GHz with an average 13 watts power consumption. Meanwhile, Apple was struggling to put a G5 processor into a PowerBook in 2005 and was running into thermal challenges. “It was in these dire circumstances that Apple took notice of PA Semi,” the article states.
Bright Side of News
This article claims that the A4 uses an ARM Cortex-A9 processor (like the Nvidia Tegra and Qualcomm Snapdragon) and an ARM Mali GPU. It describes the A4 as “mostly” ARM IP.
As time goes on, I’m sure there will be “teardowns” that will tell us a lot more about what’s inside the iPad and what’s been integrated onto the A4. Meanwhile, here are three thoughts about what the A4 might tell us about the future of chip design in the mobile consumer industry:
The EDA industry can be reassured that there will always be custom hardware design. But the growing demand for IP integration and power management will place heavy demands on next-generation EDA software.
Excellent point, Gary. Reducing design costs and unit (manufacturing) costs will be absolutely critical going forward, and will be a key imperative for the EDA industry in 2010.
Richard, a fourth point to the three that you've listed ... groundbreaking electronic products that require SoC will be ones envisioned to have sales in numbers to merit the effort financially, not just in engineering. So EDA will also need to provide solutions that also improve ROI on such designs (e.g., cycle time reduction). That way, we will more likely see a proliferation of such electronic marvels offered by a wide variety of suppliers, rather than the opposite. :)
Great insight into how a product like this is put together that can only be told by a Silicon Valley insider!