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Anyone Recognize this Qbus card?

W

w2hx

Experienced Member
Joined
Aug 20, 2014
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84
I picked up a bare-bones PDP-11/23 a few weeks ago and it had this strange quad size card in it. Seems to allow another dual size card to be inserted into it.
https://w2hx.com/?prefix=x/What-Is-It/PDP-11-Thing/Board1/

For other pictures of this thingy, you can see here:
https://w2hx.com/?prefix=x/What-Is-It/PDP-11-Thing/

It also seems to have a floppy (RX02) controller card made by Charles River Data Systems (CRDS) called FC-202.

Any info on the board in the first link would be immensely appreciated!

73 Eugene W2HX
 
It's a Qinverter, the QBus/Unibus interface.
It works both ways, i.e. when stuck in a QBus backplane with a CPU, then the Unibus devices can be used.
When the Unibus has the CPU, then the devices on the QBus can be used.
Not to be used with a CPU on both sides.
 
Cool, with that you can have your modern Qbus system control old legacy Unibus drives and the like! Perhaps it was meant to replace older 11/34 and the like hardware? Don’t know when they stopped selling Unibus hardware. RT-11 and RSX-11 worked the same on the two different platforms; PDP-11 assembler also appears to be the same regardless of the hardware, at least in my limited experience.
 
As hobbyists IMO we tend to forget that a lot of PDP-11 installations controlled equipment, industrial processes, and other unique applications, rather than simply doing IT/DP tasks. So there was an existing customer investment in business-specific Unibus-based interfaces that often needed to be preserved/supported despite migration to a Qbus-based processor. It wasn't all about access to old HDD (e.g.). Hence you see Qbus-based processors backfit into Unibus-based machines (exemplar: 11/84) as well as Qbus-based machines with a Unibus-interface (like the QNIVERTER).
 
I do have a 11/24 with graphics. The console is a VT100 box with the video out looped back into the graphics card, this to have an console OSD. Maybe one get DECWindows running on this PDP. The 11/24 is extended by a 16 slot A/B qbus backplane hosting the I/O cards. The system is to test jet engines to display engine metrics on the graphics screen.
 
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