8 Nov
2000
8 Nov
'00
2:57 p.m.
ClassicCmp wrote:
When facing the wirewrap side of the backplane, it's the two pins, two in from
the right-hand side of the left hand connector (confused yet?) So something
like:
........xx.. ..................
........xx.. ..................
These signals are essentially grant signals. There's a single wire-or interrupt
request line and a similar line for data channel requests; when the CPU decides
to honor the request it drives the INTA or DCHA line (which are the two signals
being jumpered). The signals "enter" at the bottom of the slot and hit logic on
the board which passes the signal out the top of the slot if the board isn't
requesting service, or block the signal and drive the device's six-bit device
code onto the bus if it is -- hence giving the device physically closest to the
CPU higher priority.
On Wed, Nov 08, 2000 at 08:50:29AM -0700, Bruce Ray
wrote:
I think most of these cards are compatible with the
Nova 3, but what
about the RIANDA disk controller in the "MEM I/O OPT" slot ?
Depending on the _type_ of Nova bus backplane there are memory-only,
memory-I/O and I/O-only slots. An I/O controller can be stuck in
either an I/O or memory-I/O slot.
But...
Many DG controller carry interface signals to the device by making use
of backplane pins which are unused on the slot in question (for example,
in the case of an I/O slot, pins which carry memory signals) by wirewrapping
the device connector to the backplane (essentially marrying the device
to that and only that slot).
There are two
main I/O daisey chain signals on a standard Nova/Eclipse
backplane - interrupt priority in/out and data channel request in/out - and
they usually should be jumpered across unused slots if other I/O cards exist
higher in the chassis.
Right, can you tell me between what pins these signals should be jumpered ? I assume there should be just a wire-wrap between
those pins ?
Yes, from the top of the last occupied slot to the bottom of the next occupied slot.
Depending on the artwork, you may be able to see the traces which carry these
signals between ajacent slots.
Oh, and don't forget to remove any existing jumpers that bypass the boads that
you're installing ;-)
--
Chris Kennedy
chris(a)mainecoon.com
http://www.mainecoon.com
PGP fingerprint: 4E99 10B6 7253 B048 6685 6CBC 55E1 20A3 108D AB97