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Unibus priority grant question

Activmaker

Experienced Member
Joined
Apr 3, 2018
Messages
66
Location
Paris, France
Hi,

I would like to reproduce the "Jumper box" present in unibus devices boards (RL11 for example), to select to priority level. The logic of this part should be a little bit more complex than simple SPST switches.. Until now, I didn't find any schema that show circuitry "inside" this part. Is anybody knows how it works ? After analyzing schematic of RL11, for using level 5 (Example) :

1) BR 5 must be link to the board , other level must left "off". Simple SPST with a common point ,should work. Easy part.
2) BG IN 4,6,7 must link to BG OUT 4,6,7 => All BG pass through the board, except BG5
3) BG IN 5 is linked to the BG IN of the board.
4) BG OUT of the board is linked to BG5 OUT. =>BG5 OUT is driven by the board. Either the board doesn't need to intercept grant, then it drive BG OUT=BG IN, or board want to intercept BG and in this case , drive to low the BG OUT to avoid grant propagation.

If anybody can help on this part , I will appreciate. Thanks.
 

AK6DN

Veteran Member
Joined
Aug 23, 2010
Messages
1,013
Location
Silicon Valley USA
These plug-ins are just a bunch of wires between pins. No active circuitry at all.

For example, BR5 jumper:
 

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