HelpPC 2.10 Quick Reference Utility Copyright 1991 David Jurgens

                    INT 2A,80 - Begin DOS Critical Section

       AH = 80h
       AL = critical section identifier (00-0F)
          = 01  DOS kernel, SHARE.EXE and network data structure integrity
          = 02  DOS kernel, device driver exclusivity
          = 05  IFSFUNC (Installable File System, IFS, DOS 4.0+)
          = 06  IFSFUNC (Installable File System, IFS, DOS 4.0+)
          = 08  ASSIGN.COM
       returns nothing

       - indicates that the region of code being entered should not be
         interrupted and identifies the critical region
       - this function is not normally called by user applications but is
         often hooked to monitor if DOS is in a critical section
       - this information is necessary to reenter DOS using the swappable
         data area returned by INT 21,5D subfunction 0B
       - see  Bibliography reference to "Undocumented DOS"

Esc or Alt-X to exit int 2a,80 Home/PgUp/PgDn/End ←↑↓→
Converted to HTML in 2006 by Timo Bingmann