/SET FILE MAP BIT SUBROUTINE
/ENTER WITH AC = BLOCK#
/EXTERNAL: MAPAD
SFLBT  0
       DAC SFLBT0   /SAVE BLOCK#
       AND (1760    /GET WORD POINTER
       CLL!RTR
       RTR
       TAD MAPAD
       DAC SFLBT1   /SAVE
       LAC SFLBT0   /GET BIT POSITION
       AND (17
       CMA
       DAC SFLBT0
       CLA!CLL!CML   /SET AC =0, L = 1
       RAR          /SHIFT RIGHT
       ISZ SFLBT0
       JMP .-2
       DAC SFLBT0    /SAVE
       CMA
       AND* SFLBT1  /ZERO BIT
       TAD SFLBT0    /NOW SET IT
       DAC* SFLBT1   /REPLACE MAP WORD
       JMP* SFLBT
SFLBT0 0
SFLBT1 0