; **** main (for testing only) ****
      
      
      mov al,3fh        ;print al
      call h2a
      
      
      hlt    
      
      
     
;******************************************
;name:     h2a
;
;Author:   Dan Kohn
;
;Date:     11/16/06
;
;Function: Print a 8 bit hex value to the 
;          display
;
;ON Call: AL must contain the value to 
;         display (00-FF) 
;
;On Ret: all reg restored to previous value
;****************************************** 
h2a:  push ax
      push bx    
      
      mov bl,al     ;store original value
      
      shr al,4      ;move upper digit to lower nibble
      call h1a      ;and print
      
      mov al,bl     ;restore original value
      and al,0fh    ;remove upper digit
      call h1a      ;and print
      
      pop bx
      pop ax
      
      ret                                 
      
;******************************************
;name:     H1A
;
;Author:   Dan Kohn
;
;Date:     11/16/06
;
;Function: Print a hex digit to the display
;
;ON Call: AL must contain the digit to 
;         display (0-F) in the lower nibble
;
;On Ret: all reg restored to previous value
;******************************************
h1a:  push ax
  
      add al,30h    ;add 30h to digit
      
      cmp al,3ah    ;if char '0'-'9'
      jl  p1        ;jump

      add al,7      ;if not add 7 to get
                    ;digit 'A' - 'F'

      
p1:   mov ah,0eh    ;print digit
      int 10h
      
      pop ax    
      
      ret