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Oh, the perils of working when overtired....I looked at this fresh this
morning and found the problem was a short between A7 and (inverse)A9!
This would not show up as a BUSS fault...<br><br>
So when you get a floating Address line, look for shorts between it and
something else. My logic probe did not identify this as a short as
well....only when I had the probe Synched to Address or Data could I
identify the problem - so another argument for finding a probe for your
9010A!<br><br>
John :-#)#<br><br>
<br>
<blockquote type=cite class=cite cite>Updated slightly as per some
questions raised in email...<br><br>
I was tinkering around with a sick Bally MPU board today (a rewired -17
monster for Grand Products 301), and was trying to figure out why the
6810 was not being selected...So I set the probe to <i><u>SYNC to</u></i>
DATA <i><u>(or ADDRESS)</u>,</i> and set a WRITE @ 0000 = 55
<i><u>(LOOPING)</u></i>, and then tried checking with the
<i><u>9010A's</u></i> probe for results. Curiously enough, the
<i><u>Synched</u></i> probe showed nothing at all for A7 - Tri-State as
far as it was concerned. I though maybe the 6800 pod was defective and
pulled out another one, same result. A regular logic probe shows
everything active. <i>Need to dig out the scope next I guess...<br><br>
</i>The 6810 RAM should have been available from 0000h to 007Fh, but it
was invisible. The 6810 is good, as is the socket and wiring...curious...
shall dig around more tomorrow when had more sleep and let you folks know
the results.<br><br>
A FAQ on the 9010A might be in order at some point...<br><br>
Suggestions?<br><br>
John :-#)#<br><br>
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Received on Wed Mar 26 15:18:39 2003
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