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