Int 15 Fn 101B  - Topview - "beginc" - Begin Critical Region               [Q]

   AX = 101Bh

Return: task-switching temporarily disabled

Notes: will not task-switch until "ENDC" (AX = 101Ch) called unless task
     voluntarily releases the CPU (upon regaining the CPU, task-switching
     will again be disabled)
   suspends the caller until DOS is free

See Also: AH=0Dh"MultiDOS",AX=101Ch,AX=DE13h,AX=DE1Ch,INT 2F/AX=1681h

See Also: INT 60/DI=0602h