AMD To Unveil Bulldozer And Bobcat Chip Details

Bulldozer is a chip design that AMD has been calling a “module.” The module structure actually contains two cores and each have their own integer scheduler units and shared floating-point scheduler. Each core has one instructional thread and dedicated L1 cache. The module also contains two, 128-bit floating-point math units. The two cores and two floating-point units share fetch and decode units, as well as an L2 cache, L3 cache and a north bridge.

The dedicated parts of Bulldozer – the two cores, integer schedulers and the L1 cache – handle the bulk of the workloads and can handle the most common tasks. The shared components help reduce the die size, which cuts down cost and reduced power consumption.

Each Bulldozer processor will be composed of these different modules – an eight-core processor, for example, is made up of four modules – but the modules are transparent to the hardware, applications and operating system. The OS, for instance, sees an eight-core processor and not four separate modules.

For AMD, the question is whether the company can sell a new generation of Opteron processors that use this module design compared to the more straightforward approach Intel has with its Xeon chips.

Laptop Focused Bobcat

While Bulldozer is complicated, the Bobcat microarchitecture is a more straightforward advancement. This chip, which AMD indicates can run with a sub-one watt thermal envelope, is clearly designed to work with different portable devices and ultra-thin laptops. It’s also clear that AMD is targeting Intel’s Atom processor.

What will make Bobcat different than Atom is its out-of-order execution engine, which breaks data apart and allows for instructions to run in parallel, as well as offering improved performance. Intel’s Atom chips, on the other hand, use an in-order execution pipeline, which means the core will have to accept one set of instructions first before moving onto the next step.

The design also allows for clock and power gating, which allows the chip to work with portable devices while saving battery life.

From AMD’s perspective, the out-of-order execution engineering combined with the low-power design will give Bobcat an advantage over Atom since it allows for high performance. AMD has also made a number of other improvements, including instruction sets that support virtualisation.

However, the most important part of Bobcat is that it will be the first x86 processor core to work with AMD’s APU, or accelerated processing unit, design, which looks to combine graphics and the CPU on one piece of silicon. The first of these APU chips – “Ontario” – is scheduled for a 2011 release, although AMD is not offering specifics just yet.