[Coco] ceramics ...

[jdaggett at gate.net]

Mark

free looped wire wrap wire posses all kinds of transmission 
problems. Yes twisting a wire with a ground or a differential signal 
wires and you get about 450 Ohm transmission line.  LSTTL inputs 
are about 2K OHms with a shunt capacitance of about 6 pF. If you 
have a fanout off 4 then you have a closer match to 450 OHms

Again  Mark I have 23 yrs experience in digital and analog design. 
Including RF matching and transmission lines. DO NOT DISH THE 
THEORY. IF it were not for the theory your pratical knowledge 
would not work. 

james


On 4 Sep 2004 at 7:44, Mark Marlette wrote:

Date sent:      	Sat, 04 Sep 2004 07:44:33 -0500
To:             	CoCoList for Color Computer Enthusiasts 
<coco at maltedmedia.com>
From:           	Mark Marlette <mmarlett at isd.net>
Subject:        	Re: [Coco] ceramics ...
Send reply to:  	CoCoList for Color Computer Enthusiasts 
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> At 9/3/2004 10:29 PM -0400, you wrote:
> 
> james,
> 
> A major test manufacture did this as their interface in to the digital
> test engine. 100MHZ resolution, min, max, and no mans land(three
> state) detection on the digital signal. I was a Test Engineer on this
> system. I knew this system inside and out. So well in fact the company
> hired me and ran the Midwest Regional Office for six years.
> 
> Again, design for it and it will work. We did it, not once, but on
> over 50 test interfaces over several years.
> 
> I never said ringing was due to the clock. Please go back and re-read
> my statement. I would also say that ringing was not from my wire wrap
> board either. It was from the impedance mismatches of the transmission
> line that was the wire wrap. We learned to twist the wire wrap at 8-10
> twists per inch to match the line. Termination was also required. In
> the end, a board could run 24/7 on this tester, thinking it was in the
> system and we could check prop delays, ringing, low level driver
> outputs, etc..... It worked and well. These were digital data
> transmission systems that are employed today in the Navy's ships and
> SSN class submarines.
> 
> Text book to real life experience. You must use them both.
> 
> Mark
> 
> 
> 
> >Mark
> >
> >The mismatches and ringing are not due to the clock but due to your
> >wire wrap board. I would never wire wrap any board that operated any
> >clock over 2 MHz. Basic understanding of reflection coefficients and
> >transmission line theory can tell you that far better than any $500K
> >digital tester can.
> >
> >james
> >
> >On 3 Sep 2004 at 16:10, mmarlett at isd.net wrote:
> >
> >From:                   mmarlett at isd.net
> >To:                     coco at maltedmedia.com
> >Date sent:              Fri, 3 Sep 2004 16:10:59 -0500
> >Subject:                Re: [Coco] ceramics ...
> >Send reply to:          mmarlett at isd.net,
> >         CoCoList for Color Computer Enthusiasts
> ><coco at maltedmedia.com>
> >         <mailto:coco-
> >request at maltedmedia.com?subject=unsubscribe>
> >         <mailto:coco-
> >request at maltedmedia.com?subject=subscribe>
> >
> > > Paul,
> > >
> > > That would then point to a motherboard issue.
> > >
> > > I have done 10MHZ with wirewrap on a $500K digital tester. Results
> > > and not real good for repeatability. TONS of ringing due to
> > > reflections, mismatches and coupling. 40MHZ, lucky???
> > >
> > > What did your display look like??? Could you correct the monitor
> > > enough?
> > >
> > > Mark
> > > >--- mmarlett at isd.net wrote:
> > > >
> > > >> james,
> > > >>
> > > >> Common knowledge for most. Kind of like telling
> > > >> my Son that just because
> > > >> the RPM gauge runs in the RED doesn't mean the
> > > >> engine will run forever
> > > >> there.
> > > >>
> > > >> The GIME, TCC1014A....Same thing here, sure you
> > > >> can run it faster. I have
> > > >> modified the XTAL to 32MHZ for a true 2MHZ and
> > > >> adjusted the internals of my
> > > >> monitor to compensate. My experience has been
> > > >> that the GIME/motherboard or
> > > >> whatever becomes unstable. This is my personal
> > > >> experience. Roll them back
> > > >> and they work just fine. All my mod'd machines
> > > >> have all been returned to
> > > >> stock speeds due to reliability reasons.
> > > >>
> > > >> What overclocking have you done to the GIME and
> > > >> what were your results?
> > > >> Please provide revision information, if
> > > >> relevant to your test cases.
> > > >>
> > > >> Mark
> > > >--snipped--
> > > >
> > > >I've run my hand-wired cocozilla at 40MHz,
> > > >runs fine.
> > > >
> > > >Paul Barton
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >_______________________________
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