3. RADEON Gets Mobile

ATi's last mobile graphics chip, the 'Rage Mobility' was based on the desktop chip 'Rage 128', so it's not surprising that the new 'Mobility RADEON' has its roots in ATi's latest desktop chip, the RADEON. However to reduce silicon real estate and power requirements, Mobility RADEON represents a significantly stripped-down version of the RADEON chip we know. While RADEON comes with two rendering pipelines, each including three texturing units, Mobility RADEON has only got one of them, cutting the possible fill rate in half. The transform and lighting unit of RADEON, ATI calls it 'Charisma Engine', is not present in Mobility RADEON either, thus leaving NVIDIA's upcoming GeForce2Go as the only mobile graphics chip with integrated T&L. The core and memory clock of Mobility RADEON can go up to 200 MHz, thus reaching the same clock rates at RADEON. However, the notebook maker will decide which core/memory clock will meet the power consumption and thermal requirements of its notebook and it is very unlikely that any of the upcoming notebooks with Mobility RADEON will run that chip at a clock as fast as 200 MHz.

Other important features of RADEON remained in Mobility RADEON. ATi's new mobile chip will include the 'HyperZ' technology, which is supposed to reduce Z-buffer bandwidth requirements, and the iDCT and motion compensation features for MPEG2/DVD playback will be found in Mobility Radeon as well. ATi added a dual monitor solution called 'HydraVision', competing with GeForce2Go's 'TwinView'. Since Intel's introduction of SpeedStep, a power saving solution that reduces clock and voltage of Intel's mobile processors once the notebook is battery-operated, a similar technology made its way into the design of mobile graphics chips too. Mobility RADEON will come with a power saving feature that will reduce clock and voltage when the notebook is not hooked to an AC-power outlet.

Mobility Radeon will come with integrated graphics memory of 8 MB or 16 MB in size, which is connected to the core via a 128-bit wide memory interface. The external memory that can be added to Mobility RADEON to sum up to up the huge size of 64 MB of video memory, but it interacts with the graphics core over an only 64-bit wide interface.

Comparing Mobility RADEON to NVIDIA's GeForce2Go shows its strengths and weaknesses. GeForce2Go comes with integrated T&L and offers a higher pixel fill rate as well as texel fill rate. However, Mobility RADEON is able to do without external video memory, it improves MPEG2/DVD decoding with its integrated iDCT and it is supposed to have significantly lower power requirements than GeForce2Go, although ATi wouldn't supply us with any actual numbers.