Re: FPGAs: basic question: two-level AND-OR vs. two-level OR-AND

Peter Alfke · 2003-08-06T22:05:00+00:00

The classical, so-called SRAM-based FPGAs implement logic in 4-inputLook-Up Tables, each with one output, implementing any function of thosefour inputs. AND and OR are just more primitive ways of expressing logicfunctionality. That's also why Karnaugh maps have become meaningless. Ifyou can express it as a function of four variables, there is nothingmore to do or to be optimized: It fits in one LUT.Peter Alfke ==========Neil Zanella wrote:

Aug 06, 2003 0 Replies

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Peter Alfke 22 years ago

> Hello,
>
> In view of the fact that most field programmable gate arrays are designed to
> accomodate two-level AND-OR expressions how can an FPGA synthesizer benefit
> from computing both a minimal AND-OR expression and a minimal OR-AND
> expression and then choosing the one of lower cost?
>
> Thanks,
>
> Neil

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