[Hardware] Notes on packing serial cores into Xilinx devices

Dan Oetting dan_oetting at uswest.net
Fri Aug 13 11:20:01 EDT 2004


On Aug 13, 2004, at 1:50 AM, david fleischer wrote:

> John,
> A few general notes:
> Running a project is much more than sitting down and
> compiling code. There needs to be an infrastructure to
> organize the development and distribute the data.
> In the end it would be very sad if every one ended up
> with an FPGA board next to the solar panel on their
> roof and no way to coordinate the data.

An uncoordinated search is not as efficient as a well coordinated 
search. The efficiency in terms of the average time to find the key is 
something like 1/e due to overlaps. So on average it would take 2.7 
times as long to search and there is no guaranteed maximum time. But on 
the plus side, the winner gets the full $10,000.00, there is no 
advantage for anyone to run a bogus client, and there is no overhead 
managing the key space.

The efficiencies of the coordinated search don't kick in until a 
significant fraction of the key space has been searched. So users could 
jump in today and start searching random blocks with very little chance 
of overlap. As long as the block structure of the key space is defined 
early, the random blocks searched can be merged into the coordinated 
search later.

Assuming that the cash reward is the only reason for participating and 
the d.net payoff schedual remains the same and not counting the initial 
cost of hardware and operating costs, at what percentage of the 
keyspace searched does it become advantageous to stop random searching 
and join the coordinated search? [PS: this is just a math problem and 
not intended to reflect reality]

> I read the pointer to the Virtex device; in order for
> it to be worth-while, I think it ideally needs to cost
> about20$. This is about the cost of the Spartan chips?

Using some reasonable value for cracking rate and operating cost for 
some piece of hardware, what is the break-even acquisition cost for 
that hardware. [PS: this is trick question, what is the trick?]



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