.model  small

        .stack  100h

        .data
HexDigit   DB       '0123456789ABCDEF'   ;
Mybyte     DB       27h                  ;
                                                   
        .code
main    PROC
        include pcmac.inc
        _begin

        mov      bx, OFFSET HexDigit  ; Point to the table                 
        mov      al, mybyte           ;                                    
        mov      cl, 4                ;                                   
        shr      al, cl               ; do the high bits first             
        xlat                          ; Get the ASCII value for this number
        _PutCh   al                   ;                                    
        mov      al, mybyte           ;                                    
        and      al, 0Fh              ; do the low bits next               
        xlat                          ; Get the ASCII value for this number
        _PutCh   al                   ;                                    

        _PutCh  10, 13

       _exit
main    ENDP
        END     main

We can use a similiar approch to solve a number of problems. If you have to deal with a character set from IBM called EBCDIC, you can use the an array to hold the equivalent characters, where the EBCDIC value is the index into the array, giving you the ASCII character.

We can have an array of ASCII characters, where we change all of the lowercase characters to be uppercase, and then we can convert the lowercase to uppercase.

All of those examples will allow us to exploit the xlat instruction.

UMBC | CSEE