Prior to this year’s WWDC, several rumours mentioned the possibility of an updated graphics core appearing in the new iPhone. Indeed, Phill Shiller’s keynote hinted that the 3GS sports more than just upgraded memory and CPU. The current-generation iPhone and iPod Touch utilise the PowerVR MBX core which is fully OpenGL 1.1 compliant, whereas Phil specifically mentioned support for 2.0 in the iPhone.
While not proven in any current marketing literature or official tear-downs, simple deduction would lead any careful reader to the conclusion that instead of recycling the current-generation’s MBX GPU, Apple have overhauled the 3GS with the newer PowerVR SGX processor. Imagination’s website points out the major differences between the two chips:
Where POWERVR MBX delivers fully compliant OpenGL ES 1.1 capabilities as well as OpenVG 1.0 vector graphics and extensive 2D capabilities, the fifth generation POWERVR SGX Series5 architecture takes the TBDR capability to a new level. With a level of scalability from 1 to 8 pipelines and beyond, based on the unique Universal Scalable Shader Engine (USSE), POWERVR SGX brings fully compliant OpenGL ES 2.0 shader-based graphics capability to mobile and consumer platforms. However, backwards compatibility also ensures that any applications developed for POWERVR MBX not only execute, but do so with better performance and efficiency than ever before.
Think of the step from one generation to the next as the difference between the Voodoo 2 and the more powerful Riva TNT 2 which back in the day, was competing for fastest card with 3DFX’s own Voodoo 3.
While highly unlikely that the 3GS supports true HD video decoding it is in the very least apropos to wonder if Apple also chose to include Imagination’s HD decoding unit. Keynotes are often more hype than substance and this years WWDC leaves many questions unanswered.