SYSTEM COMMUNICATION TABLE  (.SCOM)
  
        WORD           PURPOSE
------------------------------------------------------------------------
    .SCOM           First free register below resident loader.
    .SCOM + 1       First free register above resident monitor.
    .SCOM + 2       First free register.
    .SCOM + 3       Last free register.
    .SCOM + 4       Core parameters:
                            Bit 6   1=Non-resident Monitor in core
                            Bit 7   1=Page Mode
    .SCOM + 5       System program starting location.
    .SCOM + 6       User starting location & for Linking Loader:
                            Bit 0   1=DDT Load
                            Bit 1   1=G Load
                            Bit 2   1=No-symbol-table Load
    .SCOM + 7-11    Numbers of devices already in core.
    .SCOM + 12-15   Reserved for API.
    .SCOM + 16      Contains PC on interupts.
    .SCOM + 17      Contains AC on interupts.
    .SCOM + 20      First free register in extra 4K Page.
                             Bit 0   1=12, 20, or 28K System
 
                       ---.END OF .SCOM TABLE---