All input is done using the EXOS read character and read block calls. Read block is supported for compatibility with other devices although it is not very likely to be used. The keyboard is not an output device and so will not accept write character or write block function calls.
With the exception of the function keys which can be programmed with arbitrary strings, each key produces a single ASCII code. Many keys will produce different codes when used in conjunction with the CTRL, SHIFT or ALT keys.
The keyboard is always in one of four modes: normal, shiftlock, capslock or altlock. The default mode is normal. The mode can be changed by various key combinations:
CTRL LOCK - Enters caps-lock mode.
SHIFT LOCK - Enters shift-lock mode.
ALT LOCK - Enters alt-lock mode .
LOCK - Returns to normal mode.
When the keyboard is in any of the lock modes then it behaves as if the appropriate SHIFT, CTRL or ALT key was held down permanenty. If the appropriate key is held down during a lock mode then it temporarily counteracts the effect of the lock. Thus for example in shiftlock mode the action of the SHIFT key is effectively reversed. In this example if the CTRL key is used while in shiftlock modes it will behave as if it was in normal mode. This applies to all other combinations.
The current lock mode is indicated on the status line, the first six
characters of which are reserved for the keyboard. It displays
"SHIFT", "CAPS" or "ALT" as
appropriate and is blank for normal mode.
There is an EXOS variable (LOCK_KEY) which is always set to
the current lock status according to the following codes:
0 - Unlocked.
1 - Capslock.
2 - Shiftlock.
3 - Altlock.
If this EXOS variable is changed by the user then the next keyboard interrupt will update the lock modes appropriately. Any values other than the above which are put into the variable will be changed to one of the four allowed values.
These are the ASCII codes returned by each key both normally, and with SHIFT, CTRL and ALT (all values are in hexadecimal).
Key Normal SHIFT CTRL ALT
----------- ------ ------ ------ ------
1 31 21 31 31
2 32 22 32 32
3 33 23 33 33
4 34 24 34 34
5 35 25 35 35
6 36 26 36 36
7 37 27 37 37
8 38 28 38 38
9 39 29 39 39
0 30 5F 1F 9F
- 2D 3D 2D 2D
^ 5E 7E 1E 9E
@ 40 60 00 80
[ 5B 7B 1B 9B
; 3B 2B 3B 3B
: 3A 2A 3A 3A
] 5D 7D 1D 9D
\ 5C 7C 1C 9C
, 2C 3C 2C 2C
. 2E 3E 2E 2E
/ 2F 3F 2F 2F
space 20 20 20 20
A 61 41 01 81
B 62 42 02 82
C 63 43 03 83
D 64 44 04 84
E 65 45 05 85
F 66 46 06 86
G 67 47 07 87
H 68 48 08 88
I 69 49 09 89
J 6A 4A 0A 8A
K 6B 4B 0B 8B
L 6C 4C 0C 8C
M 6D 4D 0D 8D
N 6E 4E 0E 8E
O 6F 4F 0F 8F
P 70 50 10 90
Q 71 51 11 91
R 72 52 12 92
S 73 53 13 93
T 74 54 14 94
U 75 55 15 95
V 76 56 16 96
W 77 57 17 97
X 78 58 18 98
Y 79 59 19 99
Z 7A 5A 1A 9A
ENTER 0D 0D 0D 0D
ESC 1B 1B 1B 1B
TAB 09 09 09 09
DEL A0 A1 A2 A3
ERASE A4 A5 A6 A7
INS A8 A9 AA AB
STOP 03 03 03 03
JOY UP B0 B1 B2 B3
JOY DOWN B4 B5 B6 B7
JOY LEFT B8 B9 BA BB
JOY RIGHT BC BD BE BF
FUNCTION 1 .. .. F0 F8
FUNCTION 2 .. .. F1 F9
FUNCTION 3 .. .. F2 FA
FUNCTION 4 .. .. F3 FB
FUNCTION 5 .. .. F4 FC
FUNCTION 6 .. .. F5 FD
FUNCTION 7 .. .. F6 FE
FUNCTION 8 .. .. F7 FF