+-----------------------------Logiciel---------------------------------+
               +----------------------Espace-noyau------------------------+--Espace---+
               |             +---------Noyau---------+  +--Drivers-TTY--+ | utilisat. |
 +-Matériel-+  |  +-------+  |  +---------+   +---+  |  |  +---------+  | |  +-----+  |
 | +-----+  |  |  |Drivers|  |  |         |   |   |<=|==|=>|/dev/tty1|<=|=|=>|shell|  |
 | |Ecran|<-|--|--| vidéo |<-|--|Emulateur|   | D |  |  |  +---------+  | |  +-----+  |
 | +-----+  |  |  +-------+  |  |   de    |<=>| D |  |  |               | |           |
 |+-------+ |  |  +-------+  |  |terminal |   | L |  |  |  +---------+  | |  +-----+  |
 ||Clavier|-|--|->|Drivers|--|->|         |   |   |<=|==|=>|/dev/tty2|<=|=|=>|shell|  |
 |+-------+ |  |  |Clavier|  |  +---------+   +---+  |  |  +---------+  | |  +-----+  |
 +----------+  |  +-------+  +-----------------------+  +---------------+ |           |
               +----------------------------------------------------------+-----------+
Alice a ouvert deux terminaux virtuels, sur son PC, démarrant chacun un shell.
DDL : Discipline de ligne