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  • A4 Teardown: "Nothing Revolutionary Here"


    A dissection of the A4 chip Apple designed for the iPad reveals that it's fairly conventional, incorporating a single core CPU - possibly the same one used in the iPhone 3GS - and some DRAM in a triple-layer "package-on-package" (PoP) design. Because the system-on-a-chip included the core and memory on a single piece of silicon, though, heroic measures were needed to look inside, including X-raying, soaking it in an acid bath and using a grinder to cut into the A4.

    The guys at iFixit have done methodical teardowns of everything from cameras to guitars to mopeds. They did one on Apple's newest device on Saturday, revealing elegant engineering and a fancy case design, but nothing extraordinary. One black box remained, though: Apple's homegrown A4 system-on-a-chip. The iFixit guys had done a crude dissection of the iPhone's CPU with a band-saw back in 2007, but for this job they needed more advanced techniques, so they went to Chipworks, which does reverse engineering and patent protection work for major Silicon Valley manufacturers.

    First, the A4 was X-rayed from the bottom and sides, showing the fine wirebond interconnects between the three layers. Then, the chip was dipped in acid to remove the ceramic outer layer, and was slowly ground down to reveal each individual die. The two DRAM modules had Samsung markings on them, as expected, but the CPU itself was unmarked. This indicated to iFixit's Kyle Wiens that "Apple is in firm control of the semiconductor design," rather than it being a result of Samsung engineering as is the iPhone 3GS CPU.

    The analysis supported clues that ZodTTD already identified from his dump of the iPad's I/O registry tree, indicating that the A4 is indeed a single-core processor. This strengthens the case that the CPU is a Cortex-A8, rather than a Cortex-A9 as had been theorized. The GPU can't be conclusively identified from looking at the logic, but based on benchmarks it's believed to be a PowerVR SGX 535.

    The conclusion? "There's not much revolutionary here," Kyle Wiens wrote, noting the A4 isn't all that different from the Samsung processor Apple uses in the iPhone. Only the power characteristics seem to have changed significantly, with the SoC drawing about 2.5 watts on average to give the iPad its 10 hour battery life.

    image via iFixit
    This article was originally published in forum thread: A4 Teardown: "Nothing Revolutionary Here" started by Paul Daniel Ash View original post
    Comments 32 Comments
    1. hancoma's Avatar
      hancoma -
      Wife wanted an Ipad, went and looked Saturday...well, the online movies she watches online do not work...nah, I don't think it's flash, as she can watch them on the iphone with imobilecinema.

      There went her only reason for the ipad...(she's only a user)...looking at the HP Slate as an alternative...looks pretty cool, front/rear cams, usb, flash, etc.
      This is one Apple product I will have to pass on...
    1. rel1215's Avatar
      rel1215 -
      Quote Originally Posted by MetallicaFan1991 View Post
      Wow only 256MB of ram and it's supposed to multitask soon with the games and iPad specific apps...
      is see you have a 3gs....well how does that multitask? mine has always handled my needs and then some with no lag at all......so i'd say that since it manages so well with less ram than competitors, its safe to say that iphoneOS is WAY more efficient than any of the other mobile OSs out there.....for instance...i've got the nexus one also...twice the ram as the 3gs, but since i'm running the desire rom on it, i've got the same available ram on both devices......just means that android and specifically sense is pretty memory intensive compared to iphoneOS......add the fact that iphone apps are a ***** load more robust than anything i've downloaded from android market, and it becomes pretty clear that apple is still years ahead of google in terms of how well their mobile OS's operate.
    1. iphone?3gs's Avatar
      iphone?3gs -
      Quote Originally Posted by rel1215 View Post
      the teardown also revealed that the iPad only has 256 MB of RAM. That was the most shocking thing to me. Same RAM as the 3gs.
      I know right? i love the ipad and all but 256 made me sad .... the ifixit people first said it had 256mb per die meaning 512mb total and that made me happy but then they said they were wrong and there was actually a total of 256mb ram...... it just runs so fast


      Buttttttttttttttt

      The RAM Dosent matter on this device and it is awesome with its 1 ghz processer.....

      i think
    1. nave3d's Avatar
      nave3d -
      Only 256?!? What! I'm guessing the new iPhone will be a complete let down then. I seriously thought this peice would atleast have 512mb. Running fast or not, 256mb is garbage.
    1. rhekt's Avatar
      rhekt -
      i love two things in life: statistics and dale1v's signature photo.
    1. eyathan16's Avatar
      eyathan16 -
      bummmer...neva gone buy this one,i still want a new 3gs .
    1. Imsorussian's Avatar
      Imsorussian -
      Well next year in june/july the second gen ipad will be out and then ill buy. For now im just waiting for jb for 3gs
    1. Poseidon79's Avatar
      Poseidon79 -
      I still don't understand the reasoning of wanting 512MB of RAM on the iPad when it clearly has more than enough to multitask with 256. 3.1.2 on a 3GS and 3.2 on an iPad yield the same amount of available free memory to use for multitasking. The 3GS never runs low on memory. In addition to the phone and mail apps that run all the time I have iRealsms, iPod or Pandora, and IM+. I don't think there would ever be a need to run more than 2 or 3 additional apps at the same time. You could give the thing 16GB of RAM and it still wouldn't make it any faster or more usable.
    1. monadzback's Avatar
      monadzback -
      Russian, 3gs is jb. WTF are you talking about?
    1. Poseidon79's Avatar
      Poseidon79 -
      Quote Originally Posted by monadzback View Post
      Russian, 3gs is jb. WTF are you talking about?
      An iPhone 3GS (or IPT 3G) with the new bootrom on 3.1.3 is not able to be jailbroken. All other firmwares with the new bootrom have a tethered jailbreak which people are waiting for an untethered solution as well.
    1. Maarten16's Avatar
      Maarten16 -
      Quote Originally Posted by wilsongeorge View Post
      cool, but will it blend?
      yes
      [ame=http://www.youtube.com/watch?v=lAl28d6tbko]YouTube - Will It Blend? - iPad[/ame]
    1. TheEngineer's Avatar
      TheEngineer -
      This explains why the iPad feels so sluggish.

      Scrolling while zoomed in on Safari, the response is about 2 seconds behind my finger gesture.
      Keyboard cannt keep up with my typing sometimes.
      Scrolling down large HTML or PDF files requires long screen refresh times.
      Demanding apps such as Molecule is more sluggish then a 8 year old laptop.

      Apple A4 seems to be nothing more then hype.
      10 hours isn't that long considering how lacking in power the iPad is.
      With only 256MB and a single core Arm processor, this device seems more sluggish then my old laptop from many many years ago.

      I should have gotten a ION net book. Half the price and much more powerful.