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Saturday, March 19, 2011, 11:00 am PT (02:00 pm ET)

In-depth Review: Apple's iPad 2 running iOS 4.3

Hardware: Internals

The 2011 Pad 2 incorporates Apple's A5 Application Processor, which the company custom designed with licensed technology from ARM (two Cortex-A9 general purpose processor cores) and Imagination Technologies (two SGX543 graphics processor cores), and fabs in a partnership with Samsung, although rumors suggest Apple may begin building the A5 using TSMC in the future.

The A5 chip includes 512MB of LPDDR2 RAM, a special low power design that runs faster than the Application Processor RAM used in the previous A4 (and there's now twice as much).

Unlike conventional PCs, which store most of their data on relatively slow mechanical hard drives and run multiple applications at once in 4-8 GB of RAM, iPad stores content and apps in flash RAM comparable to a Solid State Drive.

Its mobile design also dictates more strict power management, so apps don't sit idle in the background. When not active, apps are almost always frozen and may be quit by the operating system to free up more working memory.


This results in iPad's iOS using RAM differently and therefore needing less than a conventional PC. Apple is loath to even comment on the amount of installed RAM, preferring to focus on the iPad's capabilities instead of technical specifications that can be used to set up misleading comparisons. On the other hand, the company is happy to point out the iPad's A5 is clocked at 1GHz, even though the system dynamically adjusts its clock speed to conserve power.

The relative lack of other technical specification data indicates that Apple doesn't want to just build raw hardware; it wants to offer highly integrated finished products, where its iTunes, iBook, and App Store are major product features and its own first party apps like Pages, Numbers, Keynote, iMovie and GarageBand are significant differentiators.

Anyone can assemble a 1GHz processor with a certain amount of RAM and deliver it in a tablet form factor, but Apple seems uninterested in competing in the PC world of hyped specifications and appears set on converting the computing business from an amalgam of general purpose hardware and software into a series of tightly integrated products.

HP is following Apple's lead, while Google's Android attempts to push mobile devices back to the PC world, where hardware makers revolve around hardware stats and Google works to service all these devices with a single ubiquitous operating system. Interestingly, Microsoft, which defined that PC model, has more recently worked to mimic Apple's integrated approach, first with the Zune and now with Windows Phone 7, which offers somewhat of a hybrid approach in combining the PC mentality with a strict set of more integrated hardware standards.


The new iPad is fast and responsive, but last year's model wasn't exactly a straggler. The new performance is likely to be most noticeable in games, where the additional processing power of the new dual GPU cores allows for not just faster drawing but more detailed rendering. One of the first games to get the iPad 2 treatment is Infinity Blade.

While the screen's resolution is the same, the greater processing power of the A5 enabled the game developers to present the game using smoother, more detailed graphics that are visible even in the still frames below, but even more evident when actually playing animated scenes, where motion further betrays the jaggies and rough edges on the earlier model. Click on the image to view the full sized, uncompressed screen shots (Infinity Blade running on original iPad, top, and iPad 2, bottom).

Infinity Blade iPad

Infinity Blade iPad 2

In Geekbench scores, the new iPad is nearly twice as fast as the previous model in processing tasks and roughly the same in memory tests, with some surprises. Because the iPad 2 processor dynamically scales its clock speed, I tried running the test both normally and then again with the iPad supplied with power and in Airplane mode with the screen dimmed, to see if this would make any visible difference in how fast the system would run its clock (and the benchmarks).

The result: GeekBench reported a very slight increase in clock speed from 851 MHz to 855 MHz, but slightly lower scores across the board, indicating that there likely isn't any real difference in performance based upon how your system is configured. Running GeekBench on two different iPhone 4 models (the original AT&T and the new Verizon) also highlighted a slight difference in clock speed (736 MHz vs 747 MHz on the Verizon model), but again, the marginally higher clock speed was contradicted by lower scores.

While the GeekBench scores don't offer much in terms of understanding how much faster the new iPad performs relative to the previous model (or compared to the experience of iPhone 4), it is interesting to note that Apple's A5 Application Processor running at around 850MHz scores close to the baseline of a 1.6GHz PowerMac G5, which in 2003 was a very fast machine.

The entry level G5 also shipped with 256MB of RAM, half that of the new iPad 2, albeit running on a 900MHz Front Side Bus, compared to iPad 2's 250 Mhz FSB. While only a single core, single processor machine, the 64-bit 1.6 GHz G5 also had a 64 KB instruction and 32 KB data L1 cache and 512 KB L2 cache. The iPad 2's 32-bit A5 has 32 KB instruction and 32 KB data L1 cache and 1 MB L2 cache.

GeekBench iPad 2

WiFi and 3G data service

iPad is an interesting device without data service, but it becomes far more useful when it can connect to WiFi, or in its 3G versions, to either AT&T's UMTS 3G network or Verizon's CDMA EVDO 3G. While the CDMA model currently only works with Verizon, the AT&T version is sold unlocked and with a SIM card, making it usable on virtually any GSM/UMTS cellular carrier worldwide. This has resulted in that model often selling out first in retail stores, as a significant number of early iPad 2 buyers have been buying it for foreign resale, hoping to profit from Apple's delayed worldwide launch.

In the US, AT&T and Verizon now offer similar mobile data service plans. Last year, Apple used the popularity of the iPad to disrupt the market for mobile data service, first partnering with AT&T to deliver very affordable, no-contract plans unlike any that had been available previously. Verizon has largely matched AT&T, with data service that no longer includes the service startup fees that carrier formerly charged mobile users.

Despite winning these concessions on behalf of iPad users, the similar WiFi data tethering plans offered by AT&T and Verizon, and supported in iOS 4.3, now allow smartphone users to opt for a reasonably priced tethering plan that is often an even better deal than buying dedicated mobile service just for the iPad. Tethering allows multiple users to access a smartphone's data service at once, and seems to support iPad FaceTime over the mobile's 3G connection (via a WiFi tethering link). Tethered iPads also appear to get more accurate GPS data supplied by the tethered iPhone than they would be able to calculate on their own via WiFi triangulation.

The only real downside to tethering is that it may sap your more critical (and limited) smartphone battery. On Verizon, getting an incoming call or text message also interrupts 3G data service through the phone, an annoyance that isn't a problem on AT&T's network, where voice and data can occur simultaneously. With a 3G iPad model, you have dedicated bandwidth and can use it independently of your mobile phone. Unlike a smartphone contract, you can activate data service for your iPad in 30 day increments whenever you want, simply by plugging in your credit card data and activating service.

iPad 3G data

iPad 3G data

Another differentiation between the WiFi and 3G models is that audio recording quality seems to be better in the WiFi only model, apparently because the mic is mounted in the aluminum shell, rather than in the black plastic window of the 3G antenna. A report about the issue noted that "the Wi-Fi model offers markedly cleaner audio than that of the 3G, which sounds slightly muffled and echo-prone as a result. Curiously, we found the GSM 3G model’s audio to be slightly preferable to that of the CDMA model, which seemed to suffer the issues more severely."

WiFi performance on the new iPad 2 appears to be identical to that observed with the original model, obtaining about 6.2Mbps downloads and 2.66Mbps Internet uploads over an 802.11n wireless network, where a desktop system could achieve 26.88Mbps downloads and 2.2Mbps uploads (uploads in both cases were constrained by the ISP's available bandwidth).

On page 3 of 3: Camera, video, peripherals.