Keyboard Key Reassignment

The ANSI system can be used to reassign keys on the keyboard. When an application calls KbdStringIn, the reassigned key's ASCII code is converted to the specified string and is passed back to the calling application. For example, replace a with q so that whenever the a key is pressed, a q is passed to the application that is reading input.

In OS/2 2.1, keyboard remapping can be done only from an application calling KbdStringIn. In DOS, keyboard remapping must be done from the command line.

Note: Keyboard reassignment works only with OS/2 applications that use the KbdStringIn call to get input.

OS/2 mode ANSI is affected when keys are reassigned in a code-page environment. ANSI "remembers" the code page under which a key is reassigned. The keyboard subsystem checks for reassigned keys when the application calls the KbdStringIn function. When a reassigned key is detected, the ANSI support:

Checks to see what code page the requestor is running under
Looks internally to see if the key has been reassigned under that code page
If there is a key reassignment for that code page, gives the reassignment string
Otherwise, gives the original ASCII codes.

A maximum storage of 64KB can be allocated to OS/2 mode ANSI-reassigned key definitions. The table shown below contains the control sequences used to redefine the meaning of keyboard keys:

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³    ESC [#;#;...#p            ³The first ASCII code in the    ³
³or  ESC ["string"p            ³control sequence defines which ³
³or  ESC [#;"string";#;#;      ³code is being mapped.  The     ³
³    "string";#p               ³remaining numbers define the   ³
³or  any other combination     ³sequence of ASCII codes        ³
³    of strings and decimal    ³generated when this key is     ³
³    numbers                   ³intercepted.  However, if the  ³
³                              ³first code in the sequence is  ³
³                              ³0 (NULL), the first and second ³
³                              ³code make up an extended ASCII ³
³                              ³redefinition.                  ³
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To execute the examples below, either create a file that contains the following statements and then use the TYPE command to display the file that contains the statement, or execute the command at the OS/2 prompt:

Assign the A and a key to the Q and q key, respectively.

Assign the Q and q key to the A and a key, respectively:

Using a File:

ESC [65;8lp          A becomes Q
ESC [97;113p         a becomes q
ESC [81;65p          Q becomes A
ESC [113;97p         q becomes a

At the OS/2 Prompt:

prompt $e[65;8lp     A becomes Q
prompt $e[97;113p    a becomes q
prompt $e[81;65p     Q becomes A
prompt $e[113;97p    q becomes a

Reassign the F10 key to a DIR command followed by a carriage return:
Using a File:
```
ESC [0;68;"dir";13p
```
At the OS/2 Prompt:
```
  prompt $e[0;68;"dir";13p
```
The $e is the prompt command characters for ESC. The 0;68 is the extended ASCII code for the F10 key; 13 decimal is a carriage return.
The following example sets the prompt to display the current directory on the top of the screen and the current drive on the current line:
```
    prompt $e[s$e[1;30f$e[K$p$e[u$n$g
```
If the current directory is C:\FILES, and the current drive is C, this example would display:
```
             C:\FILES
C>
```

The following DOS-compatible assembly language program reassigns the F10 key to a DIR B: command followed by a carriage return:

        TITLE SET ANSI.ASM - SET F10 TO STRING FOR ANSI.SYS

CSEG    SEGMENT PARA PUBLIC 'CODE'
        ASSUME CS:CSEG,DS:CSEG
        ORG     100H
ENTPT:  JMP     SHORT START
STRING  DB      27,'[0;68;"DIR B:";13P' ;Redefine F10 key
STRSIZ  EQU     $-STRING                ;Length of above message
HANDLE  EQU     1                       ;Pre-defined file.
                                        ;Handle for standard output

START   PROC    NEAR
        MOV     BX,HANDLE               ;Standard output device
        MOV     CX,STRSIZ               ;Get size of text to be sent
        MOV     DX,OFFSET STRING        ;Pass offset of string
                                        ;To be sent
        MOV     AH,40H                  ;Function="write to device"
        INT     21h                     ;Call DOS
        RET                             ;Return to DOS
START   ENDP

CSEG    ENDS
        END     ENTPT

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