Next project: 11/24. Does it need memory?--Working-ish!

Patrick Finnegan pat at
Mon Oct 26 08:32:14 CDT 2020

On Sun, Oct 25, 2020 at 9:01 PM Chris Zach via cctalk <cctalk at>

> 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.


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