14-Jul-03
GENERATING BUSY AND ERROR FROM DAUGHTERBOARDS


DB <--> BC Communication Lines
==============================
             Specified   Current        New
MB J4*  Pin  BC Name     BC Name        BC Name        Active
--------------------------------------------------------------
SPARE0  26   DB_L3_DATA  DB_L3_DATA-i   DB_L3_DATA-i   hi
SPARE1  30   BC_BUSY     BC_BUSY   -o   DB_Busy   -i   hi
SPARE2  34   L1_ERROR    unused         DB_Error  -i   hi
SPARE3  38   L1_BUSY     unconnected
SPARE4  42   L2_ERROR    unconnected
SPARE5  46   L2_BUSY     unconnected
--------------------------------------------------------------
* MB connector J4 called J3 on BC
-i = input to BC
-o = output from BC


GENERAL SIGNAL SPECIFICATIONS
=============================

DB_L3_DATA
----------
o Usage: set by DB to indicate that DB has a complete L3 event ready
  to transfer 
o Cleared: cleared by DB after PCI burst read of DB data begins

DB_Busy
-------
o Usage: set by DB to request that the FRC raise L1BUSY to the SCL
  hub.
  - Note: Dan Edmunds claims that the time between when a geographic
    sector raises L1BUSY and when L1Accepts stop should be within a
    single 132 ns tick, although it may take slightly longer.
o Cleared: cleared by DB after its internal busy condition goes away.

DB_Error
--------
o Usage: set by DB to indicate that it is in an error state requiring
  an SCL Init.
o Cleared: cleared by DB at start of SCL Init sequence.