ATi RADEON XPRESS 200 Series: AMD Platform Chipsets
The ATi RADEON XPRESS 200 Series is one of the first chipsets for the Athlon 64 and Sempron platform with support for PCI Express graphics cards and peripherals. To outline the other main features as well, we have a basic architectural overview posted below that gives a good visual representation of the RADEON XPRESS 200's other capabilities...
As you can see, the RS480 Northbridge has support for AMD Athlon 64 / Sempron processors in dual or single channel memory configurations. The Northbridge also supports a total of 22 PCI Express lanes, with 16 being dedicated to the X16 graphics slot, two acting as a link between the North and Southbridge chips, and the four left available for PCI Express X1 slots. Note that neither the Northbridge nor the Southbridge have integrated Ethernet though. Like VIA's K8T890, ATi recommends the use of a PCI Express network controller because Gigabit Ethernet on PCI Express can deliver a bidirectional 500MB/s of total bandwidth per device.
The RADEON XPRESS 200 and 200P are essentially the same chipset, except for the 200's integrated graphics core. The two differing Northbridges, however, are pin and BIOS compatible, so implementation at the motherboard level for both chipsets should be easy for the OEMs that'll be releasing boards based on the RADEON XPRESS 200. The Southbridge, which will eventually be updated to support emerging technology like SATAII and could even add additional PCI Express lanes, supports 4X SATA and 2X PATA ports (RAID 0, 1), 8X USB 2.0 ports, and AC97 audio.
Something that you may not be familiar with in the diagram about is dubbed "Hyper Memory". Hyper Memory is a proprietary ATi technology that allows the RADEON XPRESS 200's IGP to use dedicated memory, along with system memory. If you take a close look at the image to the left of ATi's reference motherboard, you can see a single 16MB RAM chip mounted alongside the Northbridge, adjacent to the CPU socket. This memory serves as the IGP's frame buffer. But Hyper Memory can be configured in a number of modes, and with a number of different frame buffer configurations. We've got a quote from ATI to better explain how it's implemented...
"In fine interleaved mode system memory and the dedicated memory are both used simultaneously. I.E. one request goes to sideport and the next (depending upon banking algorithm) goes to system memory. In coarse interleaved mode we try to use the sideport memory first and UMA once the sideport is full. In this mode, you can think of the memory being "stacked"."
The RADEON XPRESS 200's integrated graphics give motherboard's based on this chipset some rather unique abilities. With a feature that was introduced with the Radeon 9100 IGP, SurroundView, users can power three or more independent monitors when a discreet add-in video card is used in conjunction with the integrated graphics. The 3D graphics workload is not shared amongst the different graphics processors to increase performance, but rather the multiple outputs can be used to drive their own displays. This is something many professionals may want to consider should they have a need to power more than two displays. You'll no longer have to purchase multiple video cards, or a Parhelia, to run three monitors independently when using a motherboard powered by the RADEON XPRESS 200.
The RADEON XPRESS 200's integrated graphics capabilities also open up some new doors when its used in conjunction with ATi's recently announced Theater 550 chip. With a Theater 550 chip also integrated onto a motherboard powered by the RADEON XPRESS 200, users will have access to a relatively low-cost and feature-rich media center solution. A RADEON XPRESS 200 / Theater 550 combination would make a good foundation for a Microsoft Windows XP Media Center Edition-ready PC with an advanced comb filter, intelligent noise reduction algorithm, PVR capabilities with MPEG-2 encoding and built-in audio capture functionality.