5 ms·

The iPad CPU: Details on the Apple A4

39 points by profquail 17y ago

tyrelb 17y ago
I remember when Apple brought out the Macbook Air - and it sounded like a huge partnership between Apple and Intel. What is the relationship going forward?
- sparky 17y ago
  I don't have any inside scoop here, but a huge partnership between Apple and Intel and an ARM-based iPad are not mutually exclusive. Most people acknowledge that, to get the kind of energy efficiency and battery life that people are starting to expect in mobile devices, current x86 parts are not a good solution. Nonetheless, we are stuck with x86 for anything that wants to run most existing desktop/laptop software until we come up with a virtualization, cross-compilation, or binary translation scheme that is efficient enough. If Apple wants to continue selling Mac Pros and Macbooks, they will probably stay Intel for some time. Until Intel comes out with a part that can get Apple anywhere close to the many hours or even days they require for their mobile devices, Apple has no choice but to look elsewhere, and I can't see that as a reason to end a partnership on desktop/laptop processors.
  - deleted 17y ago
    [deleted]
- ZeroGravitas 17y ago
  Do you remember when some Intel Execs trashed the ARM chips, as used in iPhone and iPads, as not being able to handle "the real internet" (Intel code for Flash support). Apple got a public apology acknowledging that Intels chips couldn't hold a candle to ARMs in this area: http://news.cnet.com/8301-13579_3-10074228-37.html http://news.cnet.com/8301-13579_3-10074228-37.html So it seems like they're happy to keep Apple sweet as long as they use the Intel chips in the appropriate devices.
- Andys 17y ago
  The "system on a chip" Atom CPU is still under development and needs a lot of work (ie. time), whereas ARM is here today.
mru 17y ago
I read somewhere that the A4 has an ARM MALI graphics processor, not an SGX.
- wmf 17y ago
  That guy also has no idea what he's talking about.
petercooper 17y ago
The core of the piece: The A4 is actually built around a CPU core based on the common ARM Cortex A9 CPU, a 32-bit core that comes in several different flavors, with different numbers of cores. In typical cases, companies like Apple actually license the CPU design -- rather than paying $278 million to acquire the whole company! If Arm Holdings could be acquired for $278m, I'm sure Apple would have done it by now. Unfortunately for Apple, though, its market cap is actually in the $2-$2.5bn range.
- dandelany 17y ago
  Granted, they do have $30bn+ in cash lying around...
  - rbanffy 17y ago
    It's more likely Steve had $278M in his expense account.
- evgen 17y ago
  At one time Apple used to own 40%+ of ARM (for the Newton) and what we know of as ARM holdings was basically a joint venture between Acorn, Apple, and VLSI. Back when they really needed cash Apple was probably pretty glad they had such a large chunk of a company whose value at the time was appreciating faster than Apple's...
- wmf 17y ago
  The point is that Apple bought PA Semi for $278M. It would be unusual to spend so much money for a processor company and then turn around and use off-the-shelf ARM processors.
  - deleted 17y ago
    [deleted]
  - rphlx 17y ago
    A PA VP told me Steve Jobs asked them to drop their nearly-finished Power design immediately to build AAPL a custom ARM SoC; they said no, so he bought them, to help them say yes. He probably could have poached their stars for a lot less than $278M, but I guess he was in a serious hurry, or just viewed $278M as not worth the hassle.
risotto 17y ago
Pure speculation on my part, but I wonder if Apple can and/or has baked trusted computing into the A4 silicon. By controlling this much of the hardware, Apple can make it next to impossible to jailbreak their devices.
- wmf 17y ago
  Wouldn't be surprising at all. http://www.arm.com/products/security/trustzone/index.html http://www.arm.com/products/security/trustzone/index.html
- blasdel 17y ago
  There was nothing stopping them before: both generations of iPhone / iPod touch chips were bespoke SoC hardware too, just via Samsung.
pvg 17y ago
This is less 'details' and more 'guesses'. There have also been (equally unconfirmed) reports that it uses a different GPU (an ARM Mali).
- timdorr 17y ago
  I stopped reading after I noticed the word "likely" is used 7 times in the single page article...
rphlx 17y ago
A 1.6GHz Intel Atom spanks an entire week of lunch money out of a 1 GHz ARM, in terms of CPU performance. No doubt AAPL can mostly hide that with faster SW, relative to Windows Vista/7. But I would hate to compile anything on A4, whereas, a $200 Linux netbook is fine for most development. IMO it's sad for something iPad's size to not have a reasonable native development environment.
- wmf 17y ago
  A 1.6GHz Intel Atom spanks a 1 GHz ARM Not necessarily; ARM claims that the Cortex A9 is the one doing the superscalar out-of-order spanking and I'm inclined to give them the benefit of the doubt.
  - chadaustin 17y ago
    I'd love to see citations on both rphlx's and wmf's claims. Not trying to sound mean - I'm honestly interested in the future of low-power computing and I kind of hope ARM wins.
    - pieter 17y ago
      Here is one link: http://perspectives.mvdirona.com/2009/09/16/ARMCortexA9SMPDesignAnnounced.aspx http://perspectives.mvdirona.com/2009/09/16/ARMCortexA9SMPDe... Also Anandtech on the Cortex A9: http://www.anandtech.com/gadgets/showdoc.aspx?i=3714&p=3 http://www.anandtech.com/gadgets/showdoc.aspx?i=3714&p=3 and the pages around that.
    - rphlx 17y ago
      Here is my reasoning -- An Atom Z530 1.6GHz core has almost exactly 2X the Dhrystone MIPS of a 1.0GHz ARMv5TE-based network SoC (I actually ran it; those are not bogus vendor marketing #s). A9 probably has much higher IPC than ARMv5 -- but I doubt it's high enough to beat an Atom running at 60% higher frequency; that is a hell of a gap to close architecturally. I also suspect Atom has higher DRAM bandwidth; the A4 pkg looks a bit small for x64 DRAM. Finally, A4 may or may not have more than 1 core; Atom definitely has 2. I am talking pure performance, not performance per watt, which is not interesting to me in this situation. I can almost always find AC if I'm using something iPad-sized.

39 points by profquail 17y ago

I remember when Apple brought out the Macbook Air - and it sounded like a huge partnership between Apple and Intel. What is the relationship going forward?

sparky 17y ago
I don't have any inside scoop here, but a huge partnership between Apple and Intel and an ARM-based iPad are not mutually exclusive. Most people acknowledge that, to get the kind of energy efficiency and battery life that people are starting to expect in mobile devices, current x86 parts are not a good solution. Nonetheless, we are stuck with x86 for anything that wants to run most existing desktop/laptop software until we come up with a virtualization, cross-compilation, or binary translation scheme that is efficient enough. If Apple wants to continue selling Mac Pros and Macbooks, they will probably stay Intel for some time. Until Intel comes out with a part that can get Apple anywhere close to the many hours or even days they require for their mobile devices, Apple has no choice but to look elsewhere, and I can't see that as a reason to end a partnership on desktop/laptop processors.
- deleted 17y ago
  [deleted]
ZeroGravitas 17y ago
Do you remember when some Intel Execs trashed the ARM chips, as used in iPhone and iPads, as not being able to handle "the real internet" (Intel code for Flash support). Apple got a public apology acknowledging that Intels chips couldn't hold a candle to ARMs in this area: http://news.cnet.com/8301-13579_3-10074228-37.html http://news.cnet.com/8301-13579_3-10074228-37.html So it seems like they're happy to keep Apple sweet as long as they use the Intel chips in the appropriate devices.
Andys 17y ago
The "system on a chip" Atom CPU is still under development and needs a lot of work (ie. time), whereas ARM is here today.

mru 17y ago

I read somewhere that the A4 has an ARM MALI graphics processor, not an SGX.

wmf 17y ago
That guy also has no idea what he's talking about.

petercooper 17y ago

The core of the piece: The A4 is actually built around a CPU core based on the common ARM Cortex A9 CPU, a 32-bit core that comes in several different flavors, with different numbers of cores. In typical cases, companies like Apple actually license the CPU design -- rather than paying $278 million to acquire the whole company! If Arm Holdings could be acquired for $278m, I'm sure Apple would have done it by now. Unfortunately for Apple, though, its market cap is actually in the $2-$2.5bn range.

dandelany 17y ago
Granted, they do have $30bn+ in cash lying around...
- rbanffy 17y ago
  It's more likely Steve had $278M in his expense account.
evgen 17y ago
At one time Apple used to own 40%+ of ARM (for the Newton) and what we know of as ARM holdings was basically a joint venture between Acorn, Apple, and VLSI. Back when they really needed cash Apple was probably pretty glad they had such a large chunk of a company whose value at the time was appreciating faster than Apple's...
wmf 17y ago
The point is that Apple bought PA Semi for $278M. It would be unusual to spend so much money for a processor company and then turn around and use off-the-shelf ARM processors.
- deleted 17y ago
  [deleted]
- rphlx 17y ago
  A PA VP told me Steve Jobs asked them to drop their nearly-finished Power design immediately to build AAPL a custom ARM SoC; they said no, so he bought them, to help them say yes. He probably could have poached their stars for a lot less than $278M, but I guess he was in a serious hurry, or just viewed $278M as not worth the hassle.

risotto 17y ago

Pure speculation on my part, but I wonder if Apple can and/or has baked trusted computing into the A4 silicon. By controlling this much of the hardware, Apple can make it next to impossible to jailbreak their devices.

wmf 17y ago
Wouldn't be surprising at all. http://www.arm.com/products/security/trustzone/index.html http://www.arm.com/products/security/trustzone/index.html
blasdel 17y ago
There was nothing stopping them before: both generations of iPhone / iPod touch chips were bespoke SoC hardware too, just via Samsung.

pvg 17y ago

This is less 'details' and more 'guesses'. There have also been (equally unconfirmed) reports that it uses a different GPU (an ARM Mali).

timdorr 17y ago
I stopped reading after I noticed the word "likely" is used 7 times in the single page article...

rphlx 17y ago

A 1.6GHz Intel Atom spanks an entire week of lunch money out of a 1 GHz ARM, in terms of CPU performance. No doubt AAPL can mostly hide that with faster SW, relative to Windows Vista/7. But I would hate to compile anything on A4, whereas, a $200 Linux netbook is fine for most development. IMO it's sad for something iPad's size to not have a reasonable native development environment.

wmf 17y ago
A 1.6GHz Intel Atom spanks a 1 GHz ARM Not necessarily; ARM claims that the Cortex A9 is the one doing the superscalar out-of-order spanking and I'm inclined to give them the benefit of the doubt.
- chadaustin 17y ago
  I'd love to see citations on both rphlx's and wmf's claims. Not trying to sound mean - I'm honestly interested in the future of low-power computing and I kind of hope ARM wins.
  - pieter 17y ago
    Here is one link: http://perspectives.mvdirona.com/2009/09/16/ARMCortexA9SMPDesignAnnounced.aspx http://perspectives.mvdirona.com/2009/09/16/ARMCortexA9SMPDe... Also Anandtech on the Cortex A9: http://www.anandtech.com/gadgets/showdoc.aspx?i=3714&p=3 http://www.anandtech.com/gadgets/showdoc.aspx?i=3714&p=3 and the pages around that.
  - rphlx 17y ago
    Here is my reasoning -- An Atom Z530 1.6GHz core has almost exactly 2X the Dhrystone MIPS of a 1.0GHz ARMv5TE-based network SoC (I actually ran it; those are not bogus vendor marketing #s). A9 probably has much higher IPC than ARMv5 -- but I doubt it's high enough to beat an Atom running at 60% higher frequency; that is a hell of a gap to close architecturally. I also suspect Atom has higher DRAM bandwidth; the A4 pkg looks a bit small for x64 DRAM. Finally, A4 may or may not have more than 1 core; Atom definitely has 2. I am talking pure performance, not performance per watt, which is not interesting to me in this situation. I can almost always find AC if I'm using something iPad-sized.