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Low-cost Reconfigurable Computing (FPGA's)

Posted by michael on from the gate-of-the-future dept.

Anonymous Coward writes: "People at the at Chinese University of Hong Kong have developed a reconfigurable computing card which uses the SDRAM memory slot instead of the PCI bus. Measurements in the paper show greatly improved bandwidth and latency - why aren't more people using this idea?"

3 of 165 comments (clear)

  1. Using memory slots for devices is a bad idea by Skapare · · Score: 5, Insightful

    Using memory slots for devices is a bad idea. The interface is not designed for devices. There are no IRQ lines. The address space can be configured by the chipset to fall anywhere in the address space of the whole machine (your device may end up starting at 0). The address space may even be interleaved with other memory devices in other slots. And the next generation of memory will use a whole different interface, and most new motherboards will soon migrate to it with little concern for backward compatibility.

    --
    now we need to go OSS in diesel cars
  2. Re:Why aren't more people... by Christian+Smith · · Score: 5, Informative


    I have also wondered why more people aren't using the memory bus for peripherals....Seriously, the PCI buss can only offer so much (132 MB/S) which is certainly going to be a problem with anything faster than gigabit ethernet


    Because the memory bus is a memory bus, and NOT a peripheral bus! Peripheral busses have things like interrupts, address space configuration, buffering, bridging, hot-plugging, and long-term stability that memory busses are simply not designed for.

    How would you like it if you couldn't use the latest whizz bang 8.4GB/s memory technology because some peripheral you bought a year earlier needs to be on a 4.8GB/s memory interface?

    Anyway, PCI v2.2 (?) offers 512MB/s in 64 bit 66MHz mode. And then there's PCI-X...

    And show me a game that is PCI/AGP bandwidth limited once textures are uploaded to the GXF card anyway. Memory is cheap, use it...


    Meanwhile, modern memory busses are upwards of 4.8Gb/s. Imagine multiple machines strung together with that kind of bandwidth between them!

    Unfortunately, those pesky laws of physics (like the speed of light) come in and put paid to schemes like this. While it may be possible to get that bandwidth between machines, the latency becomes a problem. Certainly not feasable as a memory bus.

  3. If Gates Were Reprogrammable.. by Bowie+J.+Poag · · Score: 5, Funny



    If Gates were reprogrammable, then we wouldn't be in this mess in the first place.

    --
    Bowie J. Poag