+---------------------------Logiciel--------------------------+
               +--------------Espace-noyau--------------+-Espace-utilisateur-+
               |                +------Drivers PTY----+ |                    |
               |                |  +-----esclave----+ | |                    |
               |         +---+  |  |  +----------+  | | |     +-------+      |
               |         |   |<=|==|=>|/dev/pts/0|<=|=|=|====>| shell |      | 
               |         |   |  |  |  +----------+  | | |     +-------+      |
 +-Matériel-+  |  +---+  | D |  |  |  +----------+  | | |     +-------+      |
 | +------+ |  |  |   |  | D |<=|==|=>|/dev/pts/1|<=|=|=|====>| shell |      |   
 | |Souris|-|--|->| D |  | L |  |  |  +----------+  | | |     +-------+      |
 | +------+ |  |  | R |  |   |  |  +----------------+ | |                    |
 |+-------+ |  |  | I |  |   |  |      +------+       | |                    |
 ||Clavier|-|--|->| V |  |   |<=|=====>|maitre|       | |            +-----+ |
 |+-------+ |  |  | E |  +---+  |      |(PTM) |<======|=|===========>|     | |
 | +-----+  |  |  | R |         |      +------+       | |  +-----+   |xterm| |
 | |Ecran|<-|--|--| S |         +---------------------+ |  |serv.|<=>|     | |
 | +-----+  |  |  |   |<================================|=>|  X  |   +-----+ |
 +----------+  |  +---+                                 |  +-----+           |
               +----------------------------------------+--------------------+
Alice à ouvert deux terminaux fenêtre sur son PC.
DDL : Discipline de ligne