ATI has re-invented AGP, or at least a key feature of that mid-1990s bus standard, for the PCI Express era.
Dubbed HyperMemory, ATI's "innovative technology" allows its video chips to use system memory instead of dedicated video RAM on the add-in card.
Register readers with long memories will recall this ability to use main memory was one of the selling points of the original AGP spec. over PCI, in addition to introducing a dedicated bus for graphics, of course. This memory sharing aspect of AGP was by and large rejected by video card makers because of the performance downside.
HyperMemory does exactly the same thing, this time using "the high-speed bi-directional data transfer capabilities of PCI Express".
The upshot of all this is that "HyperMemory gives ATI and its board partners the option to deliver cards with less on-board memory and instead use system memory to handle the graphics storage requirements. The result is a lower overall PC cost for the same great graphics performance".
PCI Express x16, not to mention modern DDR 2 SDRAM, may well yield sufficient bandwidth to use main memory in place of some or all on-card frame buffer RAM, but don't forget that it means reducing the amount of memory available to OS and applications by a hundred megs or so. The graphics may not take a performance hit, but the rest of the system may.
You'll note that even with HyperMemory, ATI shies away from advocating the eradication of all on-card video RAM. "HyperMemory uses intelligent memory allocation algorithms to optimise the use of available local memory and ensure critical components are placed in fast local memory when required," ATI says. "Optimal assignment of data to local or system storage is determined dynamically to ensure the best user experience."
We'll all be able to put the company's claim to the test when HyperMemory-equipped graphics cards ship. ATI expects such cards to "be announced later this year". ®
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