TTY line discipline

[Guy Harris]

 >Once signal processing is turned off with ~SIG, the input characters
 >are not checked for the INTR, SWITCH, and QUIT characters. Similarly,
 >when cannonical is turned off with ~ICANON, no checks are made for the
 >ERASE and KILL characters. the input characters are now unchecked and
 >reads will be satified directly from the input buffer subject to the
 >limitation that no read will be satisfied until 
 >	1) At least MIN characters have been received AND
 >	2) The timeout value TIME has expired ***BETWEEN CHARACTERS***
 >Note that there is no timeout for the initial character. This is important!

All correct, except that if MIN is 0, TIME *is* a timeout for the
initial character.

However, the problem he's having is that his system does *not* appear to
be completely correctly implementing the above semantics!  Instead, it
appears to be swallowing NUL characters for some reason.