Jumper J12 on AMI Voyager 25/33MHz motherboards

 American Megatrends, Inc.

Tech Tip #12.002

02/06/91


Problem:


Jumper J12 on AMI Voyager 25/33MHz motherboards is used to control

I/O / memory wait states.  We do not have a description of this

jumper in the Voyager manual.


Pin description for jumper J12:


This is the edge of the board

-----------------------------

1 o-----o 2

3 o-----o 4

5 o-----o 6

7 o-----o 8


Pin Pair 1-2:


This pin controls the memory wait states for banks one and two.

This jumper should be installed for 25/33 MHz operation.


Pin Pair 3-4 / Pin Pair 5-6


These two pin pairs are used as follows:

Pin Pair 3-4 Pin Pair 5-6 Comment

  

  Open   Open CPU-25MHz

  Shorted   Open CPU-33MHz

  Open   Shorted Reserved

  Shorted   Shorted Reserved


Pin Pair 7-8 is not used at this time.


The default setting for J12 is:


25MHz: Pin Pairs 1-2 installed

33MHz: Pin Pairs 1-2 & 3-4 installed



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