Int 21 Fn 0A  - Dos 1+ - Buffered Input                                    [D]

   AH = 0Ah
   DS:DX -> buffer (see #1033)

Return: buffer filled with user input

Notes: ^C/reak 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 #1033) is set to 00h, this call returns
     immediately without reading any input

See Also: AH=0Ch,INT 2F/AX=4810h

Format of DOS input buffer:
Offset Size    Description (Table 1033)
 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