The evolution of Apple's SoC designs

Discussion in 'Apple, Industry and Internet Discussion' started by chrmjenkins, Feb 20, 2013.

  1. macrumors 603

    chrmjenkins

    Joined:
    Oct 29, 2007
    Location:
    CA
    #1
    Good article on the history of Apple's SoC designs:

    http://www.eetimes.com/electronics-...series-family--More-than-a-hobby?pageNumber=0

    Viewing more than 2 pages is hidden behind a register wall, so I'll provide some choice excerpts.

    The fact that Intel and AMD would be the only other full custom design entities out there should show you how expensive and resource intensive a full custom layout is.

    This commitment to true custom design shows Apple's devotion to the ARM ISA and platform long term. It also shows their unwillingness to compromise on "good enough" performance and to always be the best they can be, even if the basis for comparison across platforms doesn't always exist in an easily interpretable way due to ecosystem and UI differences.

    [​IMG]
    A6 die shot

    [​IMG]
    A6X die shot

    [​IMG]
    A series family tree

    It's interesting to note that there are significant design differences beyond the GPU cores and RAM interface, which were both known and necessarily needed to be different.

    [​IMG]
    Die size allocation of A series chips

    It's important to note that die size can't increase perpetually. You start running into yield issues and cost per die that makes it uneconomical. Even if Apple didn't mind high cost and lower yield, they'd probably run into capacity issues, preventing further growth.

    It's also unavoidable that power consumption increases with die size growth. Since the A4, peak power consumption on all major SoCs have more than doubled. Designs get away with this because the CPU is executing tasks faster and turning off quicker, but there's a wall here too. Eventually a power wall is hit and the only way you can squeeze more performance out is to go more custom (as apple has done), or simply wait for a process shrink. A lot of manufacturers have been hiding this increase with larger batteries, which apple hasn't done. Fairly consistent battery performance across iphone and ipad generations is certainly an accolade given this.

    Anobit was related to NAND controllers (and specifically endurance). This would apply to both their mobile devices and their Mac lines.

    Mobile GPU makers typically don't license their designs on an architecture basis. They usually have multiple core level offerings.

    However, ImgTec does have a history of providing "custom" designs. The PS Vita has a SGX543MP4+, and the "+" has never been disclosed as to what it actually is. It could refer to their custom wideIO RAM interface, but no one has said anything.

    ImgTec has divided their next generation Rogue cores into 2 lines: The G6200/6400/6600 are 2/4/6 "cluster" variants of the core. They also have 6230/6430/6630, which add special frame buffer compression logic*. (this would allow increased performance by allowing more data to be sent to the display with a given memory bandwidth, or alternately, less power as you reduce the memory bandwidth to get the same throughput. This is all at the cost of more die area, but Apple's mobile dies are among the biggest out there in the mobile world) It's possible this was an apple requested change that was turned into an alternate product line for ImgTec.

    It's important to point out that Apple is a 10% stake holder in ImgTec, so none of this would be a surprise. ImgTec is also very well positioned as a company because they just acquired MIPS (alternate CPU licensing entity like ARM, but usually found in set top boxes) and Caustic (which produces custom ray tracing cards).

    * source: http://forum.beyond3d.com/showpost.php?p=1703350&postcount=575
     

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