Function 00h	Initialize And Access Serial Communications Port
entry   AH      00h
	AL      parms for initialization: 
		bit pattern: 
		0       word length 
		1       word length 
		2       stop bits  
		3       parity 
		4       parity 
		5       baud rate  
		6       baud rate  
		7       baud rate  
                word length     10      7 bits 
			        11      8 bits 
		stop bits       0       1 stop bit 
			        1       2 stop bits 
		parity          00      none 
			        01      odd 
			        11      even 
		baud rate       000     110 baud 
			        001     150 baud 
			        010     300 baud 
			        011     600 baud 
			        100     1200 baud 
			        101     2400 baud 
			        110     4800 baud 
			        111     9600 baud  (4800 on PCjr) 
	DX      port number 
return  AH      line status 
	AL      modem status