+---------------+
| User Program  |
|      or       |
|   Keyboard    |
|   Monitor     |
+---------------+
        ^
        |
        |
        v
+---------------+
| Resident      |
| Monitor       |
|         +-----+---------+
|         | Queue Manager |
|         +-----+---------+
+---------------+        ^
                         |
                         |
                         v   

                  +----+----+----+
                  | LS | XL | dd |
                  +----+----+----+

                         ^
                         |
                         |
                         v
              +------------------------+
              | Multiterminal Monitor  |
              | Handler Hooks          |
              +----------+-------------+
                         ^
                         |
                         v
              +----------+-------------+
              | Multiterminal Monitor  |
              | Interrupt Services     |
              +----------+-------------+
                         ^
                         |
                         |
                         v

                  +----+----+----+
                  | DL | DH | DZ |
                  +----+----+----+