Small DEC QBUS backplane

Nigel Johnson nw.johnson at
Sun Jan 31 08:05:23 CST 2021

Thanks Noel,

Yes, I tried to repair an 11/34 once after somebody plugged a peripheral
board into a memory slot - I was doing well after 3 or 4 chip chnages,
it started to come to life, until I found the 20V went right into an
d=address line of an in-house numbered ROM!

Having been warned by angels I will take another route!



Amateur Radio, the origin of the open-source concept!
Skype:  TILBURY2591 nw.johnson at

On 2021-01-30 11:51 p.m., Noel Chiappa via cctalk wrote:
>     > From: Glen Slick
>     > The KDJ11-E 11/93 has PMI signals on the CD connectors, so you need a
>     > Q/CD backplane
> I have this bit set that plugging a PMI card into a Q/Q slot will damage it?
> (I think the issue is that some PMI pins are 12V on normal QBUS; too tired
> to check tonight, I'll get to it tomorrow.)
> 	Noel

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