The Apple iPad - Anand's Analysis
by Anand Lal Shimpi on January 27, 2010 5:00 PM EST- Posted in
- Smartphones
- Mobile
The Hardware
Leading up to today’s announcement I desperately tried to figure out what hardware Apple would use for the iPad. I’ve been on a bit of an SoC kick as of late, so you can understand my fascination.
Apple acquired PA Semi back in 2008. Everyone assumed that it’s because Apple wants to start making its own SoCs for the iPhone. Well, the first results of that acquisition are in the iPad.
Apple didn’t devote much time to the SoC in the iPad other than to tell the world that it’s Apple’s own silicon and it runs at 1GHz. The SoC is called the A4. I’ve asked Apple for more details on it, but I’m not holding my breath for a response.
Given the fact that it runs the iPhone OS and nearly all iPhone apps, I’m guessing the A4 is ARMv7 based. It’s possible that Apple engineered its own architecture for the A4, but more likely that it simply took an existing ARM design and modified it to suit its needs.
If Apple wanted to save cost it would’ve gone with a Cortex A8 based processor, or if it wanted more performance it would be something more A9 like. I’m not ruling out a dual-core implementation, but given the entry level cost point I’m assuming that it’s not anything quite as fantastic.
The 1GHz operating frequency implies a 45nm manufacturing process if it’s indeed an A8 or A9-like core. If we look at Apple’s public video, it appears to render a page at Spin.com in roughly 2.7 seconds. My iPhone 3GS does the same in about 7 - 9 seconds, but it also appears to be loading a lot more content on the current Spin.com site. Even if we assume that the 600MHz Cortex A8 in the iPhone 3GS can render the same page in 5 seconds, the speedup is too big to be from a clock speed increase alone.
Based on this data alone (and the responsiveness of the UI from the videos) I’m going to say that there’s a good chance that the A4 is much closer to the A9 in terms of performance. If it’s not an A9 itself, it may be Apple’s own out-of-order design.
Then there’s battery life. Apple is claiming 10 hours of web browsing battery life, which is reasonable given the 25WHr battery, but over a month of standby power. I suspect that the ridiculous standby power is due to the fact that the 3G radio is completely shut off when the device is asleep, but even then that’s very good power consumption. If anything, Apple’s own engineering here was probably spent on making sure that the SoC’s power consumption was as low as possible. By comparison, even the best SoCs in a smartphone today can usually only offer 300 hours of standby power (12.5 days).
Apple’s battery life claims have been unusually reliable as of late, so I would say that we should expect 10 hours of useful battery life out of one of these things.
I’ve spent a lot of time talking about the CPU, but what about the GPU in the A4? Given that Apple is a shareholder in Imagination Technologies (9.5%), I’d say that it’s a pretty safe bet to assume there’s some sort of a PowerVR SGX core in here. Which core? There’s definitely the physical space to include something ridiculous, but I’m guessing it’s something relatively controlled - perhaps an SGX 535 or SGX 540 at the most.
A4 in the next iPhone?
I've been racking my brain over the past several months trying to figure out what Apple will use in the next iPhone. I figured it could be as simple as a 45nm Cortex A8 shrink, or as ridiculously sweet as a pair of Cortex A9s. With the iPad being based on Apple's own A4 SoC design, I'm guessing we'll see it (or a derivative) making an appearance in the 4th generation iPhone.
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Mike1111 - Friday, January 29, 2010 - link
Why wouldn't you? It's not like Windows where a higher ppi means smaller text.My problem with exactly 1080p would have been the aspect ratio. 16:9 is not really optimal for a tablet, 3:2 like the iPhone makes imho the most sense (with 16:9 a landscape software keyboard would take up too much screen real estate). 1920x1280 (multiple of iPhone resolution) would have been my personal favorite.
But since it's highly unlikely that Apple will change the resolution or aspect ratio anytime soon (imho not for at least 2 years), we'll have to live with 1024x768 and 4:3 for a while. Maybe if the iPad is a mega huge success Apple will develop an iPad Pro ($800-$1200 instead of $500-$830) for the high-end :)
AstroGuardian - Thursday, January 28, 2010 - link
What about DRM and it's disgusting consequences? Anand?A5 - Thursday, January 28, 2010 - link
If you still want to fight the DRM fight, I'd recommend a time machine to 5 years ago. DRM isn't going anywhere and this device isn't going to do anything worse than devices that are already out there.Sandwiched - Thursday, January 28, 2010 - link
You mentioned that the resolution is disappointing, but if the 1024x768 display is a full 9.7" diagonal, then it works out to 131.959 PPI. Considering that a common print quality is 300 DPI, and most computer monitors are in the 72-100 PPI range, I'd say that 132 PPI is pretty decent for a 9.7" screen.Now, if you'd had issue with the bezel size, I could understand that. Perhaps that will be the iPad 2 - same dimensions, smaller bezel, larger screen. :)
Mike1111 - Friday, January 29, 2010 - link
You sit a lot farther away from a computer monitor than you would from the iPad (more like book or magazine reading distance). And even 300 dpi is pretty low for a high quality magazine.The final goal for a ereader tablet should be to look like national geographics, and not just a little better than your computer monitor.
Around 200 ppi would have been okay for the iPad, 250 ppi or more would have been better (Motorola Droid has 265 ppi).
But yes, the bezel could have been smaller. I find that the bezel of the iPhone (top and bottom) is big enough for most thumbs. Plus content almost never starts immediately at the sides. And modern capacitive sensors and software should be able to differentiate between a hand holding the device and a thumb or finger interacting with the screen. I mean you could even place some capacitive sensors (really low density) in the bezel to detect where the user is holding the device to make it easier.
cjb110 - Thursday, January 28, 2010 - link
The usage model presented seems very very similar to the usage model of ChromeOS. The recent interview in Ars had the dev discussing leaving it on the couch, picking it up, browsing to a site and turning it off again.Now I think most people are assuming Chrome OS is a screen+keyboard netbook/laptop...but if iPad is slightly succesfully, I doubt it would take Google very long to get nice touchable UI in there.
Byte - Thursday, January 28, 2010 - link
Ouch, looks like apple finally hit a flop on this one.wwwcd - Thursday, January 28, 2010 - link
Too expensive for free buy!vrodic - Thursday, January 28, 2010 - link
Anand, why do you assume that A4 is ARM based? Apple has extensive development experience in PowerPC architecture, and PA Semi created PowerPC based designs. It also means that there are no ARM license costs. PowerPC is quite a power efficient architecture.Most of the OS is written in portable C code, and recompiling it to a PowerPC architecture is not a significant effort. Also, existing iPhone 3rd party apps could be recompiled with the new SDK to run on iPad, and only if they use some custom ARM assembler code the "port" would require significant effort.
Mike1111 - Thursday, January 28, 2010 - link
As far as I understand it iPhone apps run without any modifications on the iPad.