26 Oct
2020
26 Oct
'20
6:32 a.m.
On Sun, Oct 25, 2020 at 9:01 PM Chris Zach via cctalk <cctalk at classiccmp.org>
wrote:
Isn't UNIBUS simple! Sorry, Q-Bus doesn't need a terminator, doesn't
have weird DMA stuff, and if you really need to put a card on a
particular side you can always grab a DLV11 (everyone has these) and use
it as a spacer. Anyone even know why Q-Bus doesn't need termination;
they used to do it with say the BDV11 but they just stopped doing it
after awhile.
I suspect that you don't "need" termination on the QBUS if it's short
(ie a
single backplane), maybe a couple of feet of wire length. The UNIBUS
generally had a much longer bus (10s of feet isn't atypical for a well
configured system), so reflection would have been more of a problem.
Pat