“Last week, I had all but conceded that the A4 was Cortex-A8 based, but developments this week demonstrate that whatever the A4 is, it is not merely a re-hash of the Samsung iPhone processor, as so many have concluded,” Mark W. Hibben blogs for Technomicon.
“A more consistent theory is the one I have offered in the past: the A4 is derived from the PA Semi PA6T, which is a dual core Power Architecture processor,” Hibben writes. “The reason why the performance is only so-so is that the A4 is still functioning as an ARM processor emulator. A future update to iPhone OS will undoubtedly take care of this problem.”
“Aside from Apple’s natural secretiveness, probably the main motivation was to avoid scaring off the developer community. Developers have been understandably leery of major platform changes in the past. When Apple switched to PowerPC from Motorola 68K, many developers simply dropped out rather than upgrade their development tools. With Apple providing the development tools, this really isn’t a problem any more, but I still hear developers grumble at the mere mention of a processor architecture change. They shouldn’t worry,” Hibben writes. “The change in instruction set should be fairly transparent to the developer in Xcode. Most of the work to adapt to iPad that developers have to do involves the larger screen size, an adaptation they would have to make in any case.”
Hibben writes, “The perception that the A4 was Cortex-A8 based had me very worried about the future of the iPad and Apple in general. It appeared that iPad was about to be waylaid in the market place from two sides. On the one side will be Cortex-A9 based tablets and smart phones running Google OS and Flash 10.1 for Mobile. On the other side will be Windows Netbooks running Windows 7 and the new 32 nm process Intel Atom processors that are right around the corner. This would have been very stiff competition for the humble ARM Cortex-A8. Fortunately, Apple does not appear to have burdened itself with such a mill stone.”
[Thanks to MacDailyNews Reader “KenC for the heads up.]