"Doc Shipley" <doc(a)mdrconsult.com> wrote:
OK. Sanity check. A slot with an adapter using
DMA needs the NPG
grant line *removed*, and if the board in place needs it in place. Does
breaking the NPG grant for a DMA adapter break the grant for succeeding
cards?
There are three kinds of SPC modules:
1) Uses NGR - requires NPG jumper to be removed from backplane
2) Does not use NPR, and doesn't pass NPG via a trace - requires
that the NPG jumper be installed in backplane
3) Does not use NPR, and passes NPG via a trace - doesn't matter
whether NPG jumper is installed in backplane
Empty slots require either the NPG jumper OR a G727 or G7273 grant
module.
If ANY slot in the backplane does not pass grant properly (either via
a jumper or through a module), you will have problems.
If you have a module that uses NPR, and also have an NPG jumper
installed in the same backplane slot, you will have problems.
And, does that mean that all the 4x4 slots in the
system chassis are
Qbus, as in I can run an RQDX3?
Running Qbus devices in the 84 will interfere with the Unibus interface.
The 84 doesn't use true Qbus; it is hardwired for a modified Qbus for
use only with the Unibus interface.