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INT 50h, Function
4
-
Check Key
Stroke
Entry:
AH
=
4
(function
code)
Exit:
FLAGS.Z
=
1
if
no
key
stroke
is
available
(in
this
case
AX
is
undefined)
FLAGS.Z=0
if
key
stroke
is
available
AX
=
keystroke data
This function returns the next character
in
the keystroke
queue,
but
does
not
remove
it
from
the
queue.
It
is
intended
to
allow
an
application
to
check what
character
will
be
returned
by
the next
call
to
function
1.
The
difference
between
this
function
and
function
1
is
that the
character returned
is
not
removed
from
the keystroke
queue.
INT 50h,
Function 5
-
Stuff
Key
Stroke
Entry:
AH
=
5
(function
code)
BX =
Key
stroke
Exit:
AL=
Queue
full
flag
=
character
was
placed
in
the
queue
OFFh
=
character
was
not
placed
in
queue because
the
queue
was
full
This function
is
intended
to
allow
an
application
to
place
a
character
code
into
the
keystroke
queue.
The
character
code
in
BX
will
be a standard
BIOS
character
code
(single
byte
if
BL<>0,
two
byte
if
BL =
0).
The
specified
character should
be
placed
at
the
end
of
the
queue
If
the
keyboard
queue
is
full,
the character
is
discarded,
and
the
queue
full
flag
returned.
137
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