$6002/24578/WD+2:       Sector Register

ROM-Reference:

 CPY $6002  : $C35A
 INC $6002  : $C691 $C993 $CA9B
 LDA $6002  : $C68E $C990 $CA98
 STA $6002  : $C643 $C6B2 $C715 $C815 $C944 $C9B4 $CA44 $CABC
 STY $6002  : $C34C