Tandy 1000 Programmer's Reference Manual page 98

Chapter 1 I System Calls
SetCtrlCTrapping
CONTROL-C Check Function Call 33H
MS-DOS
only checks for a CONTROL-C on the controlling
device when performing function call operations 01H-0CH
to that device. Function Call 33H lets you expand this
checking to include any system call. For example, with the
CONTROL-C trapping off, all disk I/O proceeds without
interruption. With CONTROL-C trapping on, the CON-
TROL-C interrupt is given at the system call that initi-
ates the disk operation.
Note that programs using Function Calls 06H or 07H to
read CONTROL-Cs as data must ensure that the CON-
TROL-C check is off.
Entry Conditions:
AH
=
33H
AL
=
function
00H
=
Return current state
OIH
=
Set state
O O H
=
Off
OIH
=
On
DL
=
switch ( i f setting state)
Exit Conditions:
DL
=
current state
O O H
=
Off
OIH
=
On
Error Return:
AL
=
FFH
The function passed in AL was not in the range 00H-
OIH.
Example:
S e t C t r l C T r a p p i n g equ
33H
m o v dl , V a l
m o v a 1 , f u n c
mow
a 1 , S e t C t r l C T r a p p i n g
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