| ??? 11/12/06 02:52 Read: times |
#127795 - Wrong Responding to: ???'s previous message |
Richard Erlacher said:
The fact that anyone who went to engineering school when one had to be able to read, write, and spell, can read and correctly interpret schematics, while that it takes a roomful of HDL experts weeks just to agree on what a page of HDL says, is also sufficient justification. If the typical HDL user knew how much more efficient his design entry would be if he simply put in a symbol for the element he had to type up for half a day, he'd go back to schematics. Let me illustrate with an example. Following are two design fragments, one created schematically and one with VHDL. Both do the exact same thing. Which of the following designs is easier to understand? Which do you think took less time to create? Design 1: 
Design 2:
process
begin
wait until rising_edge(clk);
count <= count + '1';
end process;
Now suppose the customer comes back, as they always do, and changes the requirements of the design to be a down by 1 counter. Or an up by 3 counter. Or any arbitrary counter. Which of these designs do you think is most easily modified? (Hint: It's the HDL one) The whole point of an HDL is to abstract away meaningless low level details. |
