[SI-LIST] Re: Simulate 100MHz DRAMs for long term failures?!?!
- From: "Dimiter Popoff" <dp@xxxxxxxxxxx>
- To: <si-list@xxxxxxxxxxxxx>, <dburns@xxxxxxxxxx>
- Date: Thu, 18 Aug 2005 19:27:54 +0300
Doug,
complete agreement with what you think the list is about.
I did want to share knowledge and I posted my experience in my
first message on the thread. I would not have replied to the
subsequent investigation of my design had I not publically been
called "lucky" - the list is pretty big and the archives are searchable.
I will, of course, continue to offer experience whenever I have something
to offer just as I intend to learn from others experience for the time to come.
All this to a reasonable extent, of course. If I have to spend
again and again 10x+ the time initially intended on a posting,
eventually I'll give up - I really have better things to do than defending
my name in public forums.
Dimiter
------------------------------------------------------
Dimiter Popoff Transgalactic Instruments
http://www.tgi-sci.com
------------------------------------------------------
-------Original Message-------
> From: Douglas Burns <dburns@xxxxxxxxxx>
> Subject: [SI-LIST] Re: Simulate 100MHz DRAMs for long term failures?!?!
> Sent: Aug 18 '05 15:51
>
> Dimiter,
>
> It's unfortunate that you do not want to talk about how you approached this
> or other problems. I'd never call into question your design expertise and I
> don't think that was the point of this entire chain. You have had multiple
> sucessful projects, so you must be doing something right, but we all learn
> something when we, as a group, discuss how we view problems and the approach
> we take to solve them. That is where this list turns into an educational
> classroom. Some of the best interchanges on this list occur when people
> share some of the details of problems they are seeing and how they are
> trying to solve a problem.
> Just my 2 cents.
>
> Best Regards
>
> Doug
>
> -----Original Message-----
> From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]On
> Behalf Of Dimiter Popoff
> Sent: Wednesday, August 17, 2005 4:16 PM
> To: si-list@xxxxxxxxxxxxx; dburns@xxxxxxxxxx
> Subject: [SI-LIST] Re: Simulate 100MHz DRAMs for long term failures?!?!
>
>
> Doug,
> your take on how a design process takes place is generally correct.
> However, when I posted my first message I just supplied information
> I had and I did not - nor do I now - want to tell my lifestory. I am not
> interested
> in explaining how I do my work and how very best I am, I let my work speak
> for itself.
> The number of complaint-free designs I have - owned by me or by other
> people - during
> the past 20 years suggests that there has been more than luck to it; I did
> mention that. Now if anyone has problems to believe or swallow that,
> well, too bad. Any further investigations on the matter will have
> to go without my assistance, I have closed this design effort 5 years ago
> and moved to other things.
>
> Dimiter
>
> ------------------------------------------------------
> Dimiter Popoff Transgalactic Instruments
>
> http://www.tgi-sci.com
> ------------------------------------------------------
>
>
>
>
> -------Original Message-------
> > From: Douglas Burns <dburns@xxxxxxxxxx>
> > Subject: [SI-LIST] Re: Simulate 100MHz DRAMs for long term failures?!?!
> > Sent: Aug 17 '05 20:19
> >
> > Dimiter,
> >
> > I think what people are really stating is that a good design practice
> > requires a design methodology
> > to determine how to approach a design. In terms of the discussion, I
> think
> > the question being asked
> > was what methodology did you use. It seems to me that you just didn't
> guess,
> > but used your
> > experience from previous work to define your methodology. Scott gave a
> good
> > example of a
> > methodology to determine the criticality of a signal for overshoot
> concerns.
> > If you used that type
> > of methodology when doing your 5 year old design (i.e. your knew your
> > risetime of your signal
> > was much greater than the round trip delay of the signal or you reviewed
> the
> > spec's to see what
> > the max overshoot spec was and determined by back of the envelope
> > calculations that you had
> > sufficient margin), then you used good engineering judgment when
> assessing
> > the risk of not
> > simulating the design and the proper operation is due to your good
> judgment.
> > If however, you
> > did not know the component overshoot spec or review the edgerate vs.
> > interconnect length
> > (pkg/etch/pkg) or other such review and you did just implemented it, then
> > I'd agree that luck
> > had a hand in the design. (That luck being we are talking about a 5 year
> old
> > technology and
> > the edgerates were probably fairly slow compared today's edgerates and
> the
> > chip in question
> > could probably support AC transients greater than 0.5V above DC, thus
> fact
> > that you see no
> > failures would not be much of a surprise.)
> >
> > In terms of a consultants advice, a good consultant would not suggest
> > simulating the obvious,
> > but be able to identify where rules of thumb apply, where a design is on
> the
> > edge and simulation
> > may be warranted, and lastly what parts of a design absolutely require
> > analysis. That is the value of
> > the consultant, to know the difference and how to solve issues that the
> > customer may have little
> > experience with. If they mislead the customer, the result is generally
> the
> > lack of repeat business
> > and a bad reputation.
> >
> > Best Regards,
> >
> > Doug
> >
> > -----Original Message-----
> > From: si-list-bounce@xxxxxxxxxxxxx
> [mailto:si-list-bounce@xxxxxxxxxxxxx]On
> > Behalf Of Dimiter Popoff
> > Sent: Tuesday, August 16, 2005 8:41 PM
> > To: si-list@xxxxxxxxxxxxx
> > Subject: [SI-LIST] Re: Simulate 100MHz DRAMs for long term failures?!?!
> >
> >
> > > But the conditions have to be "just right" to be able to do that....
> >
> > Being able to recognize these conditions is what makes one a design
> > engineer.
> >
> > Dimiter
> >
> > (somewhat astonished at the interest a 5 year old design of mine can
> > raise...
> > seems there is no lack of people being keen on justifuying this or
> > that overdesign decision they took)
> >
> > ------------------------------------------------------
> > Dimiter Popoff Transgalactic Instruments
> >
> > http://www.tgi-sci.com
> > ------------------------------------------------------
> >
> >
> >
> >
> > -------Original Message-------
> > > From: Aubrey_Sparkman@xxxxxxxx
> > > Subject: [SI-LIST] Re: Simulate 100MHz DRAMs for long term failures?!?!
> > > Sent: Aug 17 '05 03:07
> > >
> > > Jeff,
> > > I absolutely LOVE your analogy. Heck, I'll even add to it. When I
> was
> > > younger, I actually put out a match in gasoline. But the conditions
> > > have to be "just right" to be able to do that....=20
> > >
> > > Please DON'T try that at home!
> > >
> > > :-)
> > >
> > >
> > > Aubrey Sparkman=20
> > > Enterprise Engineering Signal Integrity Team
> > > Dell, Inc.=20
> > > Aubrey_Sparkman@xxxxxxxx=20
> > > (512) 723-3592
> > >
> > > -----Original Message-----
> > > From: si-list-bounce@xxxxxxxxxxxxx
> [mailto:si-list-bounce@xxxxxxxxxxxxx]
> > > On Behalf Of Loyer, Jeff
> > > Sent: Tuesday, August 16, 2005 6:59 PM
> > > To: si-list@xxxxxxxxxxxxx
> > > Subject: [SI-LIST] Simulate 100MHz DRAMs for long term failures?!?!
> > >
> > > I'll probably hate myself in the morning, but just can't help it...
> > > (title of thread changed also)
> > >
> > > I was cleaning car parts yesterday. I had a flashback to cleaning
> parts
> > > in the 1970's when I was a mechanic. Cleaned 'em in gasoline, with a
> > > cigarette hanging out of my mouth. Did it for years, never had a
> > > problem. Worked with lots of people who had the same experience.
> > >
> > > My personal experience suggests that there's no danger in cleaning car
> > > parts in gasoline while smoking cigarettes. Others suggest otherwise.
> > > =3D20
> > >
> > > I might conclude that there's a conspiracy among folks to force me to
> > > buy more expensive cleansers and quit enjoying a harmless vice while
> > > engaged in brainless activities.
> > >
> > > Instead, I've long since decided that I was pretty lucky (though my
> > > liver may later say otherwise). I use a very different method to
> clean
> > > parts now. Heck, I even quit smoking many years ago (it's a great
> excuse
> > > to spoil myself on my "quit smoking anniversary"!).
> > >
> > > While I think it's always good to question whether we're being
> > > overcautious and expending resources on stuff we don't care about, I
> > > think it's also prudent to worry about stuff that other very
> > > knowledgeable people get upset about. =3D20
> > >
> > > I also know that often it isn't the super-duper fast busses that kill
> a
> > > platform - it's the "supposedly DC" or other slow bus that wasn't
> given
> > > a 2nd thought. It's risetime that kills us, not clock frequency.
> =3D20
> > >
> > > And finally, one figure of merit for an engineer is whether they can
> do
> > > a quick "back-of-the-envelope" calculation that gives us an idea of
> the
> > > risk associated with a bus. I thought Scott did a nice job of that
> > > (though I didn't look at it too intensely). Unless I could dispute
> some
> > > part of those calculations, I'd conclude the bus you're talking about
> > > deserves consideration.
> > >
> > > My 2cents,
> > > Jeff Loyer
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