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Re: Amount of wire and logic

Started by Matthew Hicks August 11, 2007
Old examples?  I wonder what the breakdown is on the number of FPGAs you 
ship, Virtex-II Pro vs Virtex-4 vs Virtex-5.  Since you aren't shipping all 
the Virtex-5s yet, an I still can't find small unit quatities of Virtex-4s, 
I bet the Virtex-II Pro is still very relevant.


---Matthew Hicks


> What do you want to achieve with these theoretical considerations? > As I said, routability is not the problem anymore .. > And why do you use 5-year old examples (Virtex-2Pro?) > I prefer to address real problems using today's devices... > Peter Alfke >> If yes, my first impression is that : >> High-end device in a family provides "DECREASED ROUTABILITY" than >> low- >> end device in a family. >> For example, Virtex-II Pro-100 will provide "DECREASED ROUTABILITY" >> than Virtex-II Pro-20. >> >> Because: >> (1) Maximum fan-out that a single wire can drive is 'constant' for >> different devices. >> (2) As device size increases, there will be decreased amount of "long >> distance" wires, when wires are used up for neighbor logics.
Old examples?  I wonder what the breakdown is on the number of FPGAs you 
ship, Virtex-II Pro vs Virtex-4 vs Virtex-5.  Since you aren't shipping all 
the Virtex-5s yet, an I still can't find small unit quatities of Virtex-4s, 
I bet the Virtex-II Pro is still very relevant.


---Matthew Hicks


> What do you want to achieve with these theoretical considerations? > As I said, routability is not the problem anymore .. > And why do you use 5-year old examples (Virtex-2Pro?) > I prefer to address real problems using today's devices... > Peter Alfke >> If yes, my first impression is that : >> High-end device in a family provides "DECREASED ROUTABILITY" than >> low- >> end device in a family. >> For example, Virtex-II Pro-100 will provide "DECREASED ROUTABILITY" >> than Virtex-II Pro-20. >> >> Because: >> (1) Maximum fan-out that a single wire can drive is 'constant' for >> different devices. >> (2) As device size increases, there will be decreased amount of "long >> distance" wires, when wires are used up for neighbor logics.
Things obviously always look different from the inside than from the
outside.

As far as I know, Xilinx has been shipping every member of the three
announced Virtex-5 sub-families for awhile.
Most of them with the ES designation, but many also as "production".
Virtex-4 is shipping in larger volume, since it is used in our
customers' production equipment.
Virtex-2Pro is doing well, but it is 2 generations behind...
AFAIK you can order Virtex-5 parts from the two major distributors,
Avnet and NewHorizon.
That was a contentious issue a few months ago, that seems to be
resolved now.
I still have some scars from that internal battle.

I am sorry that I have driven this obscure posting so far off-topic.
Peter Alfke

On Aug 11, 5:44 pm, Matthew Hicks <mdhic...@uiuc.edu> wrote:
> Old examples? I wonder what the breakdown is on the number of FPGAs you > ship, Virtex-II Pro vs Virtex-4 vs Virtex-5. Since you aren't shipping all > the Virtex-5s yet, an I still can't find small unit quatities of Virtex-4s, > I bet the Virtex-II Pro is still very relevant. > > ---Matthew Hicks > > > What do you want to achieve with these theoretical considerations? > > As I said, routability is not the problem anymore .. > > And why do you use 5-year old examples (Virtex-2Pro?) > > I prefer to address real problems using today's devices... > > Peter Alfke > >> If yes, my first impression is that : > >> High-end device in a family provides "DECREASED ROUTABILITY" than > >> low- > >> end device in a family. > >> For example, Virtex-II Pro-100 will provide "DECREASED ROUTABILITY" > >> than Virtex-II Pro-20. > > >> Because: > >> (1) Maximum fan-out that a single wire can drive is 'constant' for > >> different devices. > >> (2) As device size increases, there will be decreased amount of "long > >> distance" wires, when wires are used up for neighbor logics.
Peter Alfke <alfke@sbcglobal.net> writes:
> AFAIK you can order Virtex-5 parts from the two major distributors, > Avnet and NewHorizon. > That was a contentious issue a few months ago, that seems to be > resolved now. > I still have some scars from that internal battle.
So is there any reason why Xilinx employees that *don't* think that customers should be able to get parts through distribution are still on the payroll? Seems like a good opportunity for Xilinx to cut costs. If you can't fire them outright, send them on the B Ark or something.
Eric, nobody wanted to prevent or sabotage this. As usual, the devil
was in the details. Distributors are independent companies; some
contracts needed amending, and we all know what happens at what speed
when the lawyers get involved.
But that is all behind us. It took some arm-twisting and a lot of
patience. More than I am known for...
Peter Alfke

On Aug 12, 3:10 pm, Eric Smith <e...@brouhaha.com> wrote:
> > So is there any reason why Xilinx employees that *don't* think that customers > should be able to get parts through distribution are still on the payroll? > Seems like a good opportunity for Xilinx to cut costs. If you can't fire > them outright, send them on the B Ark or something.
Peter Alfke <alfke@sbcglobal.net> writes:
> Eric, nobody wanted to prevent or sabotage this.
I was being (mostly) facetious, as might have been indicated by the reference to the "B Ark" from Hitchhiker's Guide to the Galaxy. I certainly appreciate your efforts at resolving these sorts of problems. However, it is still annoying that there's no longer a way to easily buy parts in small quantities for prototyping, e.g., XC3S200A-4FTG256CES: Avnet: no stock, minimum order quantity 17 NuHorizons: in stock, "call for information" (not orderable online) That was just one part I've tried to get recently, but the situation for many other Spartan 3E, 3A, and 3AN parts is the same. Somehow other semiconductor vendors manage to do a better job of this. For example, I generally don't have any trouble getting small quantities of TI parts, even for the more obscure, specialized, or recently introduced parts. The Xilinx Online Store appeared to be an attempt at solving this problem. It was not 100% successful (parts were often out of stock), but it was better than the current situation. If it's not possible to bring back the online store, perhaps Xilinx could work more closely with Digikey to get them to stock recent parts (e.g., Spartan 3E, 3A, 3AN series). Unlike Avent and NuHorizons, Digikey and Mouser don't mind dealing with small orders. Thanks, Eric