Odd Q-Bus questions 18/22bit

From: Megan <mbg_at_world.std.com>
Date: Sun Aug 16 20:51:11 1998

>That paddleboard connector on the VT100 is one of the cleverest pieces of
>design I've seen from DEC. The pins are supposed to short between the 2
>sides when there's nothing in the connector, thus linking the terminal
>logic signals to the DB25 on the back. Insert a paddleboard, and you
>disconnect them, allowing the paddleboard to connect separately to the
>VT100 logic and the outside world.

It is neat... I used that info to create my own sort of paddleboard
attachment which allowed me to have the terminal EIA/20ma
switch-selectable... I mounted a DPDT switch in the plastic panel which
goes on the back of a VT100 20ma option and wired it so it either routed
the signals through to the EIA port or shunted them off to the 20ma
option... only needed to intercept 4 signal lines, if I remember
correctly.. (or was it three).

I still have the 'option' in a drawer at work...

                                        Megan Gentry
                                        Former RT-11 Developer

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Received on Sun Aug 16 1998 - 20:51:11 BST

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