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FUNCTION 4Ch
-
Terminate Process
AX
BX
CX
DX
XXXXXXXX
XXXXXXXX
SP:
BP:
SI:
Dl:
IP:
FLG
CS
DS
SS
ES
Entry:
AH
-
4Ch
(function
code)
AL
-
Termination
status
code
Exit:
Special
This
function
is
used by an
applications
program
to
suspend
execution.
The AMI
file
for
the
currently
executing
application
will
be
closed,
and
control
returned
to
the
program which
invoked
the
one
being terminated.
The
value
in
AL
is
a
termination status
code
which
the
parent
process
receiving
control
may
interrogate
via
function
4Dh.
With
a
positive
value
specified
in
AL,
this
function
call
should be
viewed
as a process
suspension.
Sufficient
machine
state
is
preserved
in
the
AMI
by
HH
O/S
that
the
process can
be
resumed
at
a
later
time.
Thus,
a subsequent
call
to
function
4Bh
(execute
program)
specifying the
same
program and
AMI,
will
cause
control
to
return
to
the
instruction
folfowing
the
one
invoking function
4Ch.
This
means
that
with
a
positive
termination
code
in
AL,
it
is
possible
for
function
4Ch
to
return
to
the
caller.
When
a
suspended
process
is
resumed,
the
parameters
in
the registers
after
the return
from
function
4Ch
will
be
similar
to
those
when
a program
is initially
invoked.
CS:DX
will
point
to
a
copy
of
the
exec parameter
block
that
caused
the re-invocation
of
the
process.
The
resuming
process
may
examine
the
new
parameter
block
to
determine
what
action
to
take.
With a negative
termination
code
in
AL,
this
function
should
be viewed as
a
process
termination.
The
calling
program's
AMI
file is
closed
and
then
deleted.
When
the
AMI
file is
deleted
all
process
state
is
lost,
and
it
is
not possible
to
resume.
In
this
case,
function
4Ch
wi
not
return
to
the
caller.
42
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