This tells the driver to return the next character from its input buffer
without removing that character from the buffer.  The next read request
(DvRq 04H) should return the same character.

Offset Size Contents
+0      1  bLen         0eH (length of this request packet)
+1      1  bUnitNo      (not used)
+2      1  bCmd         05H (command code)
+3      2  rStatus      OUTPUT: Device Status Word must fill before exit
+5H     8  res          (reserved)
+0dH     1  bChar        OUTPUT: the character from the device
14               size of this structure

rStatus  On exit, the driver must place a DevStatusWord here.  Always
set the Done bit (bit 8).

If no characters are ready, set the Busy bit (bit 9).

bChar  on return, put the next character of the input buffer here.
Do not remove the character from the buffer.

See Also: Device Requests
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Device Request 05H: Non-destructive Input