14 Aug
2009
14 Aug
'09
12:28 a.m.
Tony Duell wrote:
Finally got a chance to do this; I hooked my logic analyzer to all the
grant signals on the last unibus slot and BG6 is held high constantly,
the others seem to be OK. I've confirmed that these are supposed to be
active high. Now to figure out what's raising the signal...
- Josh
Ok -- thanks
to the gracious help of several list members, I now know
where the NPG jumpers are. I checked them out on my backplane, and
they're all installed. Based on my understanding, this should be
correct for my current configuration -- the only card installed is a
64KW memory board, which isn't a DMA device, so the NPG jumper for that
slot should still be installed, correct?
That's right. A memory board doesn't use the NPG signal, so the jumper
should be in place.
What I would do next is grab a logic probe and the Unibus pinout (for the
terminator slot) and see which grant(s) is being asserted at the
terminator, if any. IIRC, the grants are active _high_, unlike most
Unibus signals. Check the NPG, BG4, BG5, BG6 and BG7 signals at the M9302
terminator
-tony