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Monday, February 15, 2010

iPad Saga Week 3 - The A4 Processor Trade

This article has been moved to . Please go to my new web site.


Mark W. Hibben

1 comment:

  1. Hi,
    nice article and good reasoning.
    In addition I saw the following mentioned in a forum on Ars Technica just after iPad was shown - and it felt more relevant than the media cut%pasting. After the article of yours I am even more convinced the blog post was accurate.




    Apple's A4 is a POWER based SoC that is a hybrid design based on both the POWER A2 and the PA6T. Buried in the on-die ROM is an ARM microcode translator.

    At the moment, only the firmware (iPhone OS 3.2a) is native to the A4's twin cores, and it runs iPhone / Touch apps by dedicating one core to ARM translation. Internal benchmarks put app translation at slightly below (95 %) of an iPhone 3g, but as the OS itself is being threaded on a separate core, overall performance is incredibly snappy. Steve is well pleased.

    Once the upgraded SDK is available, programmers will be able to create the iPhone equivalent of an universal binary, but when the app is purchased only the correct implementation is downloaded.

    Why go POWER? Remember that Apple have a very long history in working with POWER, and know it intimately. It was a very simple matter to shift iPhoneOS (itself a subset of Mac OS X) to the A4.