Many companies which expend vast sums of money on their own chips development prefer to tell a wide public about progress of their work. Even such companies as Sun and IBM, whose chips are used for their own solutions only, disclose the information about development long before the systems-on-chip enter the market. Such practice is widely used in the area of game consoles, PC and other devices production but it has never been supported by Cupertino team.
Costs for Apple A4 CPU development are variously estimated at $1 billion. By means of it the company managed to obtain rather long iPad’s battery life, by the way tablet is the first device using this solution.
Apple itself covers up the information about chip. The only thing that chief executive officer Steve Jobs has announced during iPad’s presentation is that its CPU is the best chip ever created for mobile devices. According to iPad description on Apple’s web-site A4 is SoC made by custom design, providing high production and low electric energy consumption.
All other data about chip was restricted but now there is necessary information for lifting the veil of this secret. Ars Technica has given further details about the processor. It emerged that the A4 is a custom 1GHz system on a chip with a single Cortex-A8 CPU and a PowerVR SGX GPU. The fact that A4 is mononucleate version of A8 Apple decided to conceal, but many quite competent sources point this is very much so. In its specifications A4 doesn’t have amount of invention from other Cortex A8-based SoCs. The difference is that I/O support is carried out to a far greater degree that is quite logically in consideration of distinctions between iPad and smartphones.
In addition, chip is fitted out with infrared unit, three UART modules, four USB moduls and keyboard controller. 30-pin output can be used as TV-outlet but such opportunity hasn’t been announced by Apple.