Re: Why the second flip-flop in Virtex-6?

On Tue, 2009-02-03 at 15:12 +0000, Joseph H Allen wrote:
> I'm surprised that the Spartan-6 integrated memory controller does not support
> DIMMs.  Also surprised that there are no integrated memory controllers in
> Virtex-6.
> 

I am not. From my experience with Virtex-5 and Spartan-3 I can say that
Spartans are terribly slow. If you put MPMC into Virtex-5, you can reach
pretty high data throughput. With a bit complex design in Spartan-3A you
will have hard time to meet at least minimum clock frequency for DDR2
devices. Hard-core memory controller in next generation Spartan devices
might help a lot.

Jan


> Note the Virtex-6 Select-IO voltage range: only up to 2.5V!  2.5V is the
> new 5V...
> 
> 

Jan Pech <invalid@void.domain> wrote:
 
> I am not. From my experience with Virtex-5 and Spartan-3 I can say that
> Spartans are terribly slow. If you put MPMC into Virtex-5, you can reach
> pretty high data throughput. With a bit complex design in Spartan-3A you
> will have hard time to meet at least minimum clock frequency for DDR2
> devices. Hard-core memory controller in next generation Spartan devices
> might help a lot.

The Digilent Spartan3E board has on board DDR RAM.

I believe DDR, not DDR2, though, but presumably they believe
the 3E can do that.  I haven't tried it yet.

-- glen