Core details

M18 core

Like the MOBILITY RADEON 9700, the MOBILITY RADEON 9800’s name is a bit misleading. While the “9800” in MOBILITY 9800 implies that its M18 core is based around RADEON 9800 technology from a year ago, ATI actually leverages X800 technology for MOBILITY RADEON 9800.

This means that the M18 core MOBILITY RADEON 9800 is based around is built on TSMC’s 0.13-micron manufacturing process with low-k dielectric, rather than RADEON 9800’s larger 0.15-micron process. The use of 0.13-micron allows ATI to cram more features into a smaller area and with reduced power requirements than if they would have relied on 0.15-micron, while low-k lets them crank up the clock frequencies without excessive crosstalk, which wastes power and ultimately generates more heat.

ATI outfits MOBILITY RADEON 9800’s M18 core with eight pixel pipelines, double the amount found on any other mobile graphics product. Coupled alongside these pixel pipelines are four vertex pipes, again doubling anything else on the market in mobile. These shading engines ensure that the MOBILITY RADEON 9800 will perform well with tomorrow’s shader-heavy DX9 titles, while at the same time providing M18 with more fill-rate than any other mobile part on the market, guaranteeing solid performance with today’s DX7 and DX8 games.

With a core clock frequency of 350MHz, MOBILITY RADEON 9800 boasts a fill rate of 2.8 Gigatexels/second. (ATI’s previous high-end offering, MOBILITY RADEON 9700, tops out at 1.8 Gigatexels/second.) This figure is just 30MHz shy of RADEON 9800 PRO on the desktop, which is clocked at 380MHz.

Block diagram

POWERPLAY features

Memory subsystem and 3Dc

Of course, having a fast graphics core means nothing if it’s being held up by its memory. To help make certain that this doesn’t happen, the MOBILITY RADEON 9800 sports a 256-bit memory interface (with four 64-bit memory controllers), another industry first. MOBILITY RADEON 9800 can be configured with up to 256MB of GDDR3 or DDR1 memory operating at 300MHz (600MHz effective), ensuring good performance at high resolutions, and hopefully with a little bit of AA and AF applied as well.

The addition of GDDR3 support is good for notebook manufacturers looking to conserve power, while GDDR3 also runs cooler than older memory types (assuming equal clock speeds). We’ve been told that Dell will be relying on DDR1 memory for their Inspiron notebook systems however, most likely because supply of GDDR3 is still tight.

ATI finishes M18 off with X800’s other main additions, 3Dc and enhanced shader support via pixel shader 2.0b. 3Dc provides compression for normal maps, which are being used in an increasing number of games, while shader model 2.0b provides increased shader lengths, up to 1,536 instructions are supported in 2.0b (versus 160 in 2.0). And of course, M18 continues to support ATI’s POWERPLAY technology, which dynamically adjusts clock speeds and voltage based on usage, as well as Clock Gating, which shuts off portions of the chip which aren’t in use.