INT 21 - DOS 1+ - BUFFERED INPUT                                                
	AH = 0Ah
	DS:DX -> buffer (see #01344)
Return: buffer filled with user input
Notes:	^C/^Break are checked, and INT 23 is called if either detected
	reads from standard input, which may be redirected under DOS 2+
	if the maximum buffer size (see #01344) is set to 00h, this call returns
	  immediately without reading any input
SeeAlso: AH=0Ch,INT 2F/AX=4810h


Format of DOS input buffer:
Offset	Size	Description	(Table 01344)
 00h	BYTE	maximum characters buffer can hold
 01h	BYTE	(call) number of chars from last input which may be recalled
		(ret) number of characters actually read, excluding CR
 02h  N BYTEs	actual characters read, including the final carriage return