Tandy 1000 Programmer's Reference Manual page 26

Chapter 1 I
System Calls
Terminate But Stay Resident
Interrupt 27H
Used to make a piece of code remain resident in the sys-
tem after its termination. This call is typically used in
.COM
files
to
allow some device-specific interrupt handler
to remain resident to process asynchronous interrupts.
When Interrupt 27H is executed, the program terminates
but is treated as an extension of
MS-DOS.
It remains res-
ident and is not overlaid by other programs when it
terminates.
This interrupt provides compatibility with earlier versions
of
MS-DOS. New programs should use the function 31H,
Keep Process.
Entry Conditions:
CS:DX
=
first byte following last byte of
code
in the
Macro Definition:
program
s t a y - r e s i d e n t m a c r o l a s t - i n s t r u c
m o v d x , o f f s e t l a s t - i n s t r u c
i n c d x
int
27H
e n d m
Example:
; C S
m u s t b e e q u a l
t o P S P
v a l u e 5 g i v e n
a t
p r o g r a m s t a r t
; ( E S
a n d D S v a l u e s )
rnov D X , L a s t A d d r e s s
int
2 7 H
; T h e r e is n o r e t u r n f r o m t h i s i n t e r r u p t
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