Summary of Status Registers				30 Nov 00


    The Door/Roof open/close sequencer distributes status bits regarding the
positions of the doors, etc.  These are reported to the Interlock Status 
Controller (ISC; aka Dave's box) which interprets them and forwards them to CONTROL.
There are 32 status bits divided into 4 8-bit status registers: a, b, c, and
d.  The following table was taken from the ISC code.  The "Msgs" below refer
to the messages on the ISC's LCD display.  Only the last two bits produce 
a message in both the 1 state and the 0 state.



    Status Registers                 Rising Edge Msg       Falling Edge Msg
    ***************                  ***************       ****************
  status register a:
    sa.7 = right door closing        Closing R. Door
    sa.6 = right roof closing        Closing R. Roof
    sa.5 = right door opening        Opening R. Door
    sa.4 = right roof opening        Opening R. Roof
    sa.3 = left door closing         Closing L. Door
    sa.2 = left roof closing         Closing L. Roof
    sa.1 = left door opening         Opening L. Door
    sa.0 = left roof opening         Opening L. Roof

  status register b:
    sb.7 = right door close limit    R. Door Closed
    sb.6 = right roof close limit    R. Roof Closed
    sb.5 = right door open limit     R. Door Opened
    sb.4 = right roof open limit     R. Roof Opened
    sb.3 = left door close limit     L. Door Closed
    sb.2 = left roof close limit     L. Roof Closed
    sb.1 = left door open limit      L. Door Opened
    sb.0 = left roof open limit      L. Roof Opened

  status register c:
    sc.7 = right door >5% open       R. Door At 5%
    sc.6 = right roof >5% open       R. Roof At 5%
**  sc.5 = right door >95% open      R. Door At 95%
 *  sc.4 = right roof >95% open      R. Roof At 95%
    sc.3 = left door >5% open        L. Door At 5%
    sc.2 = left roof >5% open        L. Roof At 5%
**  sc.1 = left door >95% open       L. Door At 95%
 *  sc.0 = left roof >95% open       L. Roof At 95%

  status register d:
**  sd.7 = right pause               Right Paused
**  sd.6 = left pause                Left Paused
**  sd.5 = pumps on                  Both Pumps On
**  sd.4 = pause                     Paused
    sd.3 = closing                   Closing Shelter
    sd.2 = opening                   Opening Shelter
    sd.1 = right pump on             Right Pump On         Right Pump Off
    sd.0 = left pump on              Left Pump On          Left Pump Off


* and ** status bits don't work properly (bug in the sequencer code?).  **
bits are frozen at 0.  The * bits appear to be confused with the ** bit 
directly above them in the table.  I.e., perhaps their erratic behaviour is
due to the sc.1 and sc.5 subroutines overwriting the sc.0 and sc.4 values,
respectively.