Function  47h   Get Current Directory 
		Places full pathname of current directory/drive into a buffer 
entry   AH      47h 
	DL      drive (0=default, 1=A:, etc.) 
	DS:SI   points to 64-byte buffer area 
return  CF      clear   DS:DI   pointer to ASCIIZ pathname of current directory 
		set     AX      error code (0Fh) 
note   String does not begin with a drive identifier or a backslash