Re: gEDA-user: random project idea

[Steven Michalske <smichalske@xxxxxxxxx>]

On Mar 28, 2008, at 10:10 AM, Steve Meier wrote:

> High speed memory is now staggering the transmission of each data line
> to minimize cross talk. High end fpga's can support qdr II memory
> devices to clock speeds of over 500 MHz. The qdr ii has two data buses
> one for read and one for writing. Each bus supports a transfer on each
> edge of the clock. This implies data rates on these buses of over 1  
> GHz.
>
> It isn't the bus rate that will limit performance it is the internal
> clock rate. 500 MHz as opposed to over 3 GHZ.
>

when you move to serial data buses they have PLL clock multipliers  
that make the serial stream operate at high frequencies.
so the I/O speed can be higher than the fabric speed.

hardkrash

> However, the fpga has all those built in multipliers.... hundreds of
> them. So for certain tasks an fpga will completely blow away a  
> standard
> intel based computer.
>
> My inclination would be to build a mother board with both a standard
> microprocessor and an additional fpga that can be programed by the
> microprocessor. A customized coprocessor so to speak.
>
> Steve Meier
>
>
>
>
> On Thu, 2008-03-27 at 19:08 -0400, DJ Delorie wrote:
>>> My understanding is that with the GHz busses on modern mobos you  
>>> need
>>
>> With a soft CPU, the busses can go slower.  I wouldn't expect such a
>> project to compete with PCs.
>>
>>> I thought it was basically impossible to get it right without
>>> assistance from the CAD tool.
>>
>> Well, we can change the CAD tool, can't we?  ;-)
>>
>>> Is this actually practically feasible with a "dumb" CAD tool like
>>> pcb?
>>
>> You'd have to limit yourself to something that fits in our skill set,
>> sure, but perhaps a less-than-GHz system would be doable.  It would  
>> be
>> neat to experiment with other cores and stuff besides the usual x86,
>> arm, and mips.  Imagine a picoblaze PC running something like DOS, or
>> a nios-linux box.
>>
>>> But it's "dumb" in the sense that it doesn't really contribute to
>>> the layout,
>>
>> It does have trace measuring, though.
>>
>>
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>
>
>
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