This tells the driver to terminate any read operation in progress and to
empty the device input buffer.

DevReq07Rec
Offset Size Contents
                                                                          
+0      1  bLen         ??H (length of this request packet)
+1      1  bUnitNo      (not used)
+2      1  bCmd         07H (command code)
+3      2  rStatus      OUTPUT: Device Status Word must fill before exit
+5H     8  res          (reserved)
13               size of this structure

rStatus  On exit, the driver must place a DevStatusWord here.  Always
set the Done bit (bit 8).  On an error, set the Done bit and
the Error bit (bit 15) and put a Device Error Code in the low
byte.

Notes:   This is the device driver "catch-point" for DOS fn 0cH (clear
and input).

See Also: Device Requests
- -

Device Request 07H: Input Flush