Re: Analysis and Design
 

"Jörg Breitenstein" <haag-streit@sunway.ch> wrote in message news:<3ef972aa$0$1053$5402220f@news.sunrise.ch>...
> Hi
> Does anyone now if there is a good methologie to analyse and design digital
> systems. There are plenty of books about VHDL, but that's the language. I'm
> looking for somenthing like SA/SD or UML for software Design. But this vor
> digital hardware.
>
> Does Ben Cohen's Book cover topics like this?
>
> Vhdl Coding Styles and Methodologies.
>
> ???
>
> Thanx
>
> Joerg
You've got at least two issues here. Programming and Digital Design.

I'm sure that VHDL programming can benefit from all the software
productivity and correctness type tools. Revision control, formal
specifications, elaborate testing. I only dabble in programming, so
I'm not sure what state of the art is today. Maybe somebody can
comment on the tools used by large multi-engineer ASIC projects.
Paying for large complicated software projects can be very expensive
and can easily go out of control. If I was paying for a large VHDL
project I'd be very concerned about these issues.

Digital logic design isn't as straight forward as it may seem. An
ounce of insight and clever partitioning can be worth a pound of
logic. Propagate/Generate bits on adder slices aren't obvious, but
can substantially reduce logic gates and give excellent speed. I
don't think there is any Holy Grail of logic design that will pop this
out. It was an important problem that lot's of people looked at and
this was a very good solution. I don't even think that optimal state
assignment and output assignment can be guaranteed. VHDL is famous
for blowing up at synthesis and using way more gates than the minimum
because the tools didn't recognize that there is a clever method
available for what you are doing.

Design reviews of Digital Logic or VHDL are incredibly educational.
Getting 8 experienced, intelligent and competitive people in a room
and asking them to criticize something can spin you up the learning
curve in a hurry. It's entertaining too, in a Dr. Laura
reach-down-their-throat-and-rip-out-their-heart sort of way :) I just
never get tired of that.

I guess I don't have a great solution for you. It's a pretty good
question though.

Roadie Roger
<http://home.earthlink.net/~roadieroger/index.htm>