Quote from: asicminer on July 24, 2011, 04:26:01 AM

Use of Block RAM (BRAM) for storage of constants [8]. Reconfigurable hardware devices
such as FPGAs often have on-board memories which can be pre-loaded.
Storing the Kt constants in these memories frees up space in the device
which can then be used to implement extra logic. The free space also leads to
improved routing and, thus, a general speed-up in circuit operation.

From "Optimisation of the SHA-2 Family of Hash Functions on FPGAs"
Robert P. McEvoy, Francis M. Crowe, Colin C. Murphy and William P. Marnane
   Department of Electrical & Electronic Engineering,
   University College Cork, Ireland
   {robertmce, francisc, cmurphy, liam}@rennes.ucc.ie

As a person who's actually done an FPGA bitcoin mining design that uses block RAM (though not in exactly this way), I know that it's part of the FPGA itself and not a seperate chip. There's no reason why a specially-designed Bitcoin mining board would need an SRAM chip; SRAM is large and slow and a Bitcoin miner needs fast access to a small amount of data. This wasn't even a competent scammer...

Edit: Oh, and the reason it doesn't use block RAM in that particular way? Doing so is only worthwhile if you're designing a standard SHA-2 hash engine that computes the hashes of variable-length pieces of data one at a time, whereas efficient Bitcoin mining compute lots of hashes of differing short pieces of data in parallel.