INT 1Bh (27)             Keyboard Break

Called when a Control-Break key sequence is encountered.


When the machine is powered on, the interrupt handler for this
interrupt just IRETs back to the caller. DOS, however, installs a
Ctrl-Break handler that sets an internal flag to signal that a
keyboard Break condition has occurred.

Notes:         DOS tests the state of the internal flag
occasionally, depending on the state of the Control-
Break Check (INT 21h, Function 33h). If the flag is
on during a test, then the string "^C", followed by
a Carriage-Return/ Line-Feed combination, is
displayed on the screen, the DOS internal flag is
reset, and INT 23h (Control-Break Exit Address) is

Note that INT 09h (Keyboard) sets the byte at
0:0471h to signal that a Control-Break key has been

See also: INT 23h
See also: 0:471h
See also: 33h

INT 1Bh (27) Keyboard Break