OK... so I got this H-27 that locks up the Qbus when it is in the grant chain
and works ok (except for interrupts) when it is past the end of the granted
devices (one or more blank Qbus slots in-between). I've pulled and tested
each and every TTL chip, but can't use the auto chip tester on the Nat'l
Semi parts. My questions are this:
What are the three jumpers for? (E-1 through E-3, between U11 and U12, and
U7 and U8)
What bus drivers/receivers directly interact with the interrupt grant chain?
If I'm lucky, it's U11 and U7 - I have plenty of 8136 chips.
What can I substitute for DS8837 and DS8839 chips, if one of them is at fault?
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Received on Tue Apr 17 2001 - 21:18:55 BST