Re: CUPL programming

Ed Casas (edc@ece.ubc.ca) Mon, 27 Nov 2000 16:41:41 -0800 

Date: Mon, 27 Nov 2000 16:41:41 -0800
From: Ed Casas <edc@ece.ubc.ca>
Subject: Re: CUPL programming



> What does including a ".d" extension mean when defining logic
> equations into CUPL programming language? In the notes it says
> that adding this extension defines the output as a "flip-flop"
> output. Does this mean that the output only occurs on the
> rising edge of the clock?

The output only changes on the rising edge of the clock.

> If so, how does this make adding the ".d" extension much
> different from leaving it out (since the rising edge of the
> clock happens so many times per millisecond)? In other words,
> what would require making the outputs of the programmed state
> machine into "flip-flop" outputs compared to making them
> "regular" outputs.

If you don't use ".d" then the output is not "registered" -- it
is a combinational function of the inputs and changes when they
do.

Without flip-flops the output would depend only on the inputs.
The flip-flops provide the "memory" required to implement a state
machine.

-- 
Ed Casas   edc@ece.ubc.ca   http://casas.ece.ubc.ca   +1 604 822-2592