Tandy 1000 Programmer's Reference Manual page 79

Chapter 1 I
System Calls
Setvector
Set Interrupt Vector
Function Call 25H
Sets a particular interrupt vector. The operating system can
then manage the interrupts on a per-process basis. This call sets
the address in the vector table for the specified interrupt to the
address of the interrupt handling routine in AL.
Note that programs should never set interrupt vectors by writing
them directly in the low memory vector table.
Entry Conditions:
AH
=
25H
AL
=
number
of
the interrupt to set
DS:DX
=
address
of
the interrupt handling routine
Macro Definition:
s e t - v e c t o r m a c r o
p u s h
mov
mov
mov
mov
i n t
P O P
endm
m Q V
Example:
I d 5 d x , i n t v e c t o r
mov ah,ZSH
mov a 1 , i n t n u m b e r
i n t
21
H
: T h e r e a r e n o e r r o r s r e t u r n e d
i n t e r r u p t , s e g - a d d r , o f f - a d d r
d5
a x , s e g - a d d r
d5 , a x
d x , o f f - a d d r
a 1 , i n t e r r u p t
ah,25H
21 H
d5
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