Empathy List Archives

PK

Poul-Henning Kamp

Wed, Nov 28, 2007 7:45 PM

In message E1IxRdG-00038h-Eg@febo.com, "Prologix" writes:

Hi Chuck,

Good work identifying the problem! Leaving out the bus driver chips was a
conscious decision based on available board space and was not made lightly.
Extensive testing had shown that not to be an issue, so far. In fact, yours
is the first reported case of a drive related problem. However, we consider
even one incident to be one too many, and will be revisiting the decision
during a future release.

I think I can report having seen the problem as well, only not
realizing the cause, because it worked flawlessly when I put my
HP59401A Bus Analyser on the bus.

--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.

In message <E1IxRdG-00038h-Eg@febo.com>, "Prologix" writes: >Hi Chuck, > >Good work identifying the problem! Leaving out the bus driver chips was a >conscious decision based on available board space and was not made lightly. >Extensive testing had shown that not to be an issue, so far. In fact, yours >is the first reported case of a drive related problem. However, we consider >even one incident to be one too many, and will be revisiting the decision >during a future release. I think I can report having seen the problem as well, only not realizing the cause, because it worked flawlessly when I put my HP59401A Bus Analyser on the bus. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk@FreeBSD.ORG | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence.

CH

Chuck Harris

Wed, Nov 28, 2007 8:39 PM

Ah yes! You gotta love it when the test instrument fixes
the problem ;-)

I recall hearing of a few instruments that had scope probes
built in to fix strange parasitic problems...

-Chuck Harris

Poul-Henning Kamp wrote:

In message E1IxRdG-00038h-Eg@febo.com, "Prologix" writes:

Hi Chuck,

Good work identifying the problem! Leaving out the bus driver chips was a
conscious decision based on available board space and was not made lightly.
Extensive testing had shown that not to be an issue, so far. In fact, yours
is the first reported case of a drive related problem. However, we consider
even one incident to be one too many, and will be revisiting the decision
during a future release.

I think I can report having seen the problem as well, only not
realizing the cause, because it worked flawlessly when I put my
HP59401A Bus Analyser on the bus.

Ah yes! You gotta love it when the test instrument fixes the problem ;-) I recall hearing of a few instruments that had scope probes built in to fix strange parasitic problems... -Chuck Harris Poul-Henning Kamp wrote: > In message <E1IxRdG-00038h-Eg@febo.com>, "Prologix" writes: >> Hi Chuck, >> >> Good work identifying the problem! Leaving out the bus driver chips was a >> conscious decision based on available board space and was not made lightly. >> Extensive testing had shown that not to be an issue, so far. In fact, yours >> is the first reported case of a drive related problem. However, we consider >> even one incident to be one too many, and will be revisiting the decision >> during a future release. > > I think I can report having seen the problem as well, only not > realizing the cause, because it worked flawlessly when I put my > HP59401A Bus Analyser on the bus. >

DF

David Forbes

Wed, Nov 28, 2007 8:51 PM

Chuck Harris wrote:

Ah yes! You gotta love it when the test instrument fixes
the problem ;-)

I recall hearing of a few instruments that had scope probes
built in to fix strange parasitic problems...

-Chuck Harris

When I designed and debugged VMEbus cards, I would joke about doing that
sometimes when I found that the scope fixed the problem. The joke got
more involved, however, when the board only worked properly with 100
channels of logic analyzer probes connected. Shipping a board with that
much stuff stuck to it might make the customer nervous. So my boss
always made me find the source of the trouble.

We did ship some boards with rows of 150pF SMT capacitors on register
select inputs of an IDT bit-slice ALU due to a die shrink that made the
internal registers get corrupted with fast incoming edges. Talk about
analog solutions to digital problems!

--David Forbes

Chuck Harris wrote: > Ah yes! You gotta love it when the test instrument fixes > the problem ;-) > > I recall hearing of a few instruments that had scope probes > built in to fix strange parasitic problems... > > -Chuck Harris When I designed and debugged VMEbus cards, I would joke about doing that sometimes when I found that the scope fixed the problem. The joke got more involved, however, when the board only worked properly with 100 channels of logic analyzer probes connected. Shipping a board with that much stuff stuck to it might make the customer nervous. So my boss always made me find the source of the trouble. We did ship some boards with rows of 150pF SMT capacitors on register select inputs of an IDT bit-slice ALU due to a die shrink that made the internal registers get corrupted with fast incoming edges. Talk about analog solutions to digital problems! --David Forbes

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