Character Code Definitions - Tandy 600 Programmer's Reference Manual

Character
Code
Definitions
There
are
two cases
with
which
the
BIOS must be concerned
when
dealing with character
codes.
The
first
case
is
that of
which
character
codes are
to
be recognized
for
display
on
the
LCD
display
and what
graphic
shape
is
to
be generated
for
each
of
these characters.
The
second case concerns
the
set of characters
which
the
user
may
type
on
the keyboard,
and
what
character codes are
to
be
returned.
The
character
set
used
for
output
to the
LCD
display
will
be
the
same
as
is
used
in
the
IBM
PC. This character set contains
256
displayable characters using
a single 8
bit
code
for
each
character defined.
The
character set
used
for input
is
a superset
of
the
IBM
PC
input
character
set.
A
single
byte
is
used
to
return the
codes
1
through
255
decimal, while
an extended code
is
used
for
special
functions.
The
extended character
codes
are two
byte
codes
with the
first
byte containing
a
binary
0,
and
the
second
byte containing
the
extended character code.
The BIOS
routine that
returns
keyboard characters
will
return single
byte characters
in
the
AL
register.
A
two
byte
extended code
will
be returned
with
AL =
and
the
extended
code
in
AH.
Keys which
don't
appear on
the
keyboard
may
be simulated
by combinations
of
other keys.
The
following table
defines the
extended
function
codes.
Those shown
with a
Y
are required,
those
shown
with
an
N
are not
required.
The
Cursor
Left 4-
and Cursor
Right
+
characters
are not
shown
in
the
IBM Keyboard Mapping
List.
These
operations
will
be
mapped
to
function
keys
in
the
IBM
keyboard,
and do
not require special characters.
Extended Function
IBM Keyboard
Non-IBM Keyboard
Code
Mapping
Mapping
Y
Break
Break
Break
N
3
ASCII
NUL
ASCII
NUL
ASCII
NUL
Y
15
Back Tab Back Tab
Shift
TAB
Y
16-25
ALT
Q.
W,
E,
R ALT
Q,
W,
E,
R ALT
Q,
W,
E,
R
ALT
T, Y, U,
I,
ALT
T,
Y,
U,
I,
ALT
T, Y, U,
I,
ALT
O, P
ALT O, P
ALT
0,
P
Y
30-38 ALT
A, S, D,
F
ALT
A, S, D,
F
ALT
A,
S,
D,
F
ALT
G, H,
J,
K
ALT
G,
H,
J,
K
ALT
G, H,
J,
K
ALT
L
ALTL ALTL
Y
44-50
ALT
Z, X, C,
V ALT
Z,
X, C,
V
ALT
Z, X, C,
V
ALT
B, N,
M
ALT
B, N,
M
ALT
B, N,
M
Y
59-68 F1-F10
F1-F10
F1-F10
Y
71
Cursor
Left
+
+
Home
CTRL
Cursor
Left
Y
72 Cursor
Up Cursor
Up
Cursor
Up
Y 73
Cursor
Up -
Page Up
Shift
Cursor
Up
Y
75 Cursor
Left
Cursor
Left
Cursor
Left
Y
77 Cursor
Right
Cursor Right
Cursor
Right
Y
79 Cursor Right
+ + End
CTRL
Cursor Right
Y
80 Cursor
Down
Cursor
Down Cursor
Down
Y
81
Cursor
Down
-
Page
Down
Shift
Cursor
Down
N 82
Insert
INS
Insert
Y
83 Delete
DEL
Delete (note
1)
Y
84-93
Shift
F1-F10
Shift
F1-F10 Shift
F1-F10
Y
94-1 03
CTRLF1-F10 CTRLF1-F10
CTRL
F1-F10
Y
104-113
ALT F1-F10
ALTF1-F10
ALT F1-F10
133