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I'm curious about the ASIC comment. Surely no one is "synthesizing" SRAM in ASIC by describing its behavior with an HDL, right? You just decide at design time to use an SRAM array of whatever size, then (for simulation) just stub it out with an appropriate HDL model that gets replaced during synthesis. The "SRAM" abstraction in that model is provided by the semiconductor fab, no?

At least, that's how I've always assumed things work.



It works as you describe, pretty much, the gnarly bit being that there's no standard interface for an SRAM (that is, SRAM is not in the standard library, unlike say simple gates.) One reason is the many different ways to implement BIST and connect the BIST signals from all memories in the chip into a coherent whole.


Here's an article (not written by me, just found by using google) that has an example how the VHDL/Verilog compiler infers to use a dual-ported SRAM from code that describes the behavior, including the bugs you'll encounter.

http://danstrother.com/2010/09/11/inferring-rams-in-fpgas/




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