HelpPC 2.10 Quick Reference Utility Copyright 1991 David Jurgens

                   INT 1B - BIOS Ctrl-Break Handler Address

       - holds address of the BIOS Ctrl-Break interrupt handler
       - called by INT 9 after Ctrl-Break key is pressed; INT 9 sets the
         BIOS keyboard head and tail pointers to the buffer start and
         places a zero word in the buffer
       - the BIOS initially sets this value to point to a simple IRET but
         DOS re-vectors this to its own code, usually 2 lines of code that
         sets an internal flag (to 3) and then returns via IRET.
       - DOS checks this flag on entry to many of its subfunctions.  If the
         flag is set, it invokes INT 23.
       - pointing this address to a null function with and IRET disables
         Ctrl-Break aborts
       - if the INT 1B code chooses to retain control of the system, it
         must issue an EOI for any interrupt pending on the 8259 and reset
         all I/O devices
       - should be terminated via an IRET
       - should not be called directly by user application

Esc or Alt-X to exit int 1b Home/PgUp/PgDn/End ←↑↓→
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