Casio IT-2000W Technical Reference Manual page 89

Secondary code
Basically a system scan code is assigned to each key, however, for some keys, different codes
will be assigned depending on the Fn key.
Code Table
The following diagram shows the relationship between the keyboard keys and primary codes.
Fn 7 8 9

4 5 6
0 1 2 3
Fn key
The Fn key is used to generate a system scanning code for the function key if it is pressed
together with a numeric key. For example, Fn+1 keys generate a system scanning code for the
F1 key, and Fn+0 keys generate a system scan code for the F10 key. However, Fn+7 to 9 keys
will not generate a system scanning code that corresponds to any function keys because they
have already been assigned to the following internal functions to be executed internally.
Operation
Fn + 7 Toggles the backlight on and off.
Fn + 8 Increases the LCD screen contrast by one increment.
Fn + 9 Decreases the LCD screen contrast by one increment.
-
CLR
Fig. 6.3
89
37 38
2E 34 35
30 31 32
Fn key not pressed
003E 003F 0040
0044 003B 003C 003D
Fn key pressed
Function
39 2D
36
1B
33 0D