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INT 59h, Function
-
Disconnect
Serial
Device from
Modem
Entry:
AH =
(function
code)
Exit:
No
registers specified
INT 59h, Function
1
-
Connect
Serial
Device
to
Modem
Entry:
AH =
1
(function
code)
AL
=
Serial port
number
Exit:
AL
=
Standard
BIOS
error
code
The
serial
port
number
parameter
in
AL
specifies to
which
serial
port
the
modem
is
to
be
attached.
If
it
is
not
possible
to
attach the
modem
to
the
requested
port,
then
an
error
indication
should
be
returned
in
AL.
It
is
acceptable
to return
an
error indication
in
AL
if
the
serial
port
requested
is
not configured
correctly to
allow
modem
communications
to
occur
(for
example:
if
the
baud
rate
is
set
too
high).
INT 59h, Function 2
-
Disconnect Telephone
Line
Entry:
AH =
2
(function
code)
Exit:
No
registers specified
This function
causes
the
telephone
line
to
go on
hook,
and
terminate the
telephone
call.
INT 59h, Function
3
-
Connect Telephone
Line
Entry:
AH
=
3
(function
code)
BX =
Device
to
connect
Exit:
AL
=
Standard
BIOS
error
code
This
function
call
takes
the
telephone
line off
hook,
and
connects
an
internal
device
to
the
line
If
the
line
is
already
off
hook, then
it
should remain so
with
no
disruption
of
the
call.
The
following
device
codes can be
specified
in
BX:
=
Telephone
Dialer
1
=
Modem
2
=
Voice
Handset
In
some
hardware
configurations,
some
of
these devices
may
be
redundant.
Connecting
a
device
implies
disconnecting
any
other device
which
may
be connected.
175
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