Function 3301h Set CTRL+C Check Flag

mov dl, BreakFlag ;00h = off, 01h = on

mov ax, 3301h ;Set CTRL+C Check Flag

int 21h

Set CTRL+C Check Flag (Function 3301h) turns the CTRL+C check flag on or off.

Parameter

BreakFlag

Specifies whether to turn CTRL+C testing on or off. If this parameter is 00h, CTRL+C testing is turned off; if this parameter is 01h, CTRL+C testing is turned on.

Return Value

This function has no return value.

Comments

If the CTRL+C check flag is off, MS-DOS checks for CTRL+C only while processing character I/O functions 01h through 0Ch. If the check flag is on, MS-DOS checks for CTRL+C while processing other I/O functions, such as disk operations.

The CTRL+C flag affects all programs. If a program changes the state of this flag, the state change remains in effect even after the program terminates. An efficient program should save the state of the flag before changing it and restore the state before terminating.