An annotated guide to iFixit's iPhone 4S tear-down

  • John Cox (Network World)
  • 15 October, 2011 03:35

The people at iFixit, who love screwdrivers more than gadgets, Friday walked us through a dissection of the Apple iPhone 4S, which goes on sale today.

Generally, the tear-downs don't uncover big surprises. Unless you think that this time Apple's decision to go with the "linear oscillating vibrator" from the Verizon iPhone 4 instead of the "rotational electric motor with counterweight" in the AT&T model is a surprise. iFixit assures us that the former is "quieter, softer, and all-around less annoying" than the latter.

FIRST LOOK: Apple iPhone 4S

The step-by-step disassembly starts with the unboxing.

Here's our take on the highlights:

The 4S battery: People almost take for granted Apple's battery engineering achievements. Apple doesn't give details on the 4S' rechargeable lithium-ion battery, except that it performs as well or better than the battery for the iPhone 4. That's quite an achievement given the 4S introduces a powerful dual-core processor, an upgraded camera and a voice interface. iFixit says the 4S battery offers an additional 0.05 watt hours compared to that of the iPhone 4.

The 8-megapixel camera: As iFixit notes, Apple has done more than just upgraded the sensor to 8 megapixels from 5. It re-engineered the entire imaging system. As Josh Topolsky notes in his iPhone 4S review for, the result of a range of interrelated improvements means the new camera takes "some of the nicest, cleanest photos I've ever seen from a mobile device. ... The 4S produced crisp, balanced, colorful photos that were surprisingly low-noise and never over-saturated." It "looks and feels like a real camera capturing true images," he adds.

Dual-core A5 processor: This has been talked about forever, of course. Based on the tear-down, AnandTech's Anand Lal Shimpi concludes that this processor "is virtually identical to what was used in the iPad 2 -- although running at a lower clock speed and likely a lower voltage as well." One feature that's surprised many, he notes, is that Apple still is using "only 512MB of RAM on the A5's PoP stack." But this indicates Apple's obsession with the "user experience." According to Shimpi, "since most apps not in use are kept out of memory to begin with, having more memory doesn't actually buy you a whole lot of performance." In addition, "there are also potential battery life concerns with larger DRAMs: more room for apps to remain resident in memory leaves more DRAM cells to refresh, which impacts power consumption (although eventually Apple will have to cross this bridge, likely with the next process node transition)," he says. "I suspect the biggest issue created by not outfitting the iPhone 4S with more DRAM is limiting game developers to smaller levels, fewer unique textures, etc. ..."

New Qualcomm cellular baseband: The tear-down shows the dual-mode 14.4Mbps HSPA+ and CDMA2000 "world phone" capability is provided by a new Qualcomm chipset, the MDM6610 (outlined in orange in the photograph), which is an upgrade from the iPhone 4's MDM6600. According to AnandTech, not much is known about the new silicon. This isn't the 4G/LTE speeds that some were hoping for. But AnandTech notes that the change supports the latest and continuing cellular network upgrades: HSDPA and HSUPA for GSM carriers, like AT&T, and CDMA2000 x 1x/EVDO Rev. A for carriers like Verizon.

Bluetooth 4.0: iFixit pinpoints this Murata chip as containing the Broadcom silicon that provides iPhone 4S with 2.4GHz 802.11n Wi-Fi connectivity, just as with iPhone 4, but also Bluetooth 4.0, apparently the first mobile device to do so (not counting the latest MacBook Air). The key difference with 4.0 radios is that they are designed for extremely low power. Terrence O'Brien, writing at Engadget, says it will enable iPhone 4S to "act as a hub -- collecting data from multiple sensors and accessories simultaneously, such as heart rate monitors," blood glucose monitors and battery of other similarly equipped devices.

John Cox covers wireless networking and mobile computing for Network World.



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