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Low-cost Reconfigurable Computing (FPGA's)
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?"
the idea of FPGA computing has been around for a little while at least (look here for examples). i think Scientific American even wrote about "configurable computers" in 1997 or so. why aren't they more popular, then?
modern processors are well-adapted to general computing tasks.
FPGAs (read: custom iron) might be good for a few specialized tasks (breaking 3DES, for instance), but most of us will be a lot happier on our UltraSparcs and Athlons and G4s.
http://danisaacs.com/temp/fccm01_pilchard.pdf
Be gentle. And mirror and post mirrors, please. Bandwith costs, and I'm poor.
- Dan I.
I have also wondered why more people aren't using the memory bus for peripherals. For instance, the VGA adaptor would greatly benefit from that interface (3d work, video games), also, using that bus as a network connection in a renderfarm would probably be nice too. 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... Meanwhile, modern memory busses are upwards of 4.8Gb/s. Imagine multiple machines strung together with that kind of bandwidth between them!
Another question I've had bouncing around in the back of my head is why no one uses MPEG decoder circuitry for MP3 playback? All the players I've tried, windows or linux, take 10-30% of the CPU for noraml playback operation. This is unacceptable when working in big apps like 3DStudio Max, make-ing a big app or running big scripts. I have an old MPEG decoder card from a Creative DVD, also I believe my G-Force has MPEG decoder acceleration... How much trouble would it be to write a driver for Winamp that uses preferred devices like that?
:)Fudboy
I guess I'm only a Fudboy, looking for that real Transmeta
This may help a little, but in general, people haven't figured out how to make FPGA-based computing sufficiently useful, cheap, and easy in order for it to catch on. Programming an FPGA is still rather hard and the architecture limits severely what you can do. And there is the chicken-and-egg problem with the boards: if you write software for them, few people can run it, and few people are motivated to buy a board because there is no software that uses it. Right now, you are probably a lot better off buying a dual processor board or a cluster than an FPGA add-on.
FPGA technology to replace (or more like having a "flashable") Current processors could/would be a great leap in computing, it would mean having a "soft-hardware upgrade", microcode or "sillicon" bugs could be addressed, but there would probably be the downside of everything else in the computing industry: companies would released bugged stuff, beta would go around like current drivers :), etc etc.
All this said, unless some big breakthrough happens, we won't see out Athlon or Pentium IV system replaced by these, the 2 main limitation of FPGA are the number of available gates, and the speed at which they operate.
While they've managed to increase the number of gates to something quite big (last time I read about this I think it was in the low million? 1 or 2, but I can't be sure), this is enough to "emulate" microcontrollers or lower end processors, but not enough for higher end microprocessors. While eventually they will catch up and maybe someone will do his thesis on emulating an Athlon off FPGA stuff, by that time we'll be at the 2nd or 3rd rev of Post-hammer processors, so it will look like today being able to emulate a 486 (granted, there could be some use in that, but none come to mind right now.. parrallel processing? 1 athlon can replace zillion of 486s...) Also the developpement of microprocessor is going at a faster pace than FPGA technology. I am not saying this couldn't happen, but it would need a serious bump in the fab process and technology to be able to reach Ghz speed, and probably few 100M's of gates.
Still, it's a very interresting technology.
--- Metamoderating abusive downgraders since my 300th post.
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
If Gates were reprogrammable, then we wouldn't be in this mess in the first place.
Bowie J. Poag
A DSP is just a very specialized CPU, primarily focusing on math intesive stuff, but less on branching and conditionals.
As any CPU they are sequential devices. The load a instruction, decode it and execute it and repeat. Though modern DSP can paralellize many intructions it's resources are still statically allocated at the time of design. A DSP with two multipliers may at most perform two multiplications at any one time.
Using a fpga on the other hand allows you to design the circuit from the ground up. now if your algorithm needs to do 20 multiplications at a time, you can do so simply by building them on the device.
Using a fpga is fundamentally different from using a DSP or microcontroller/processor. The latter is a finished circuit with an assorment of operators selectable by an instruction opcode. The former can be configured into any circuit.