WriteHexB PROC    (Not covered in the 4th edition)

   Writes an unsigned 8, 16, or 32 bit number to standard output in hexadecimal format.
   EBX must contain the TYPE the number to write (1 for BYTE, 2 for WORD, or 4 for DWORD).
   Leading zeros are inserted if necessary.

Call args:  AL, AX, or EAX = unsigned number to write.
            EBX = 1 to write AL as 2 hex digits,
            EBX = 2 to write AX as 4 hex digits,
            EBX = 4 to write EAX as 8 hex digits.

Return arg: None

Example:

      .data
      bValue BYTE 'A'

      .code
      mov  eax,bValue
      mov  ebx,TYPE bValue
      call WriteHexB

Output:  41