USER STATE   +  SYSTEM STATE ZERO  + DEEPER SYSTEM STATE
              |                     |
+-------+     |                     |
| JOB 1 |     |                     |
+-------+     |                     |
    |         |                     |
    |         |                     |
    | INTERRUPT 1  +-----------+    |
    +------------->| ROUTINE A |    |
              +    +-----------+    |
              |          |          |
              |          |          |
              |          | INTERRUPT 2  +-----------+
              |          +------------->| ROUTINE B |
              |                     +   +-----------+
              |                     |         |
              |                     |         |
              |                     |         | INTERRUPT 3  +-----------+
              |                     |         +------------->| ROUTINE C |
              |                     |                        +-----------+
              |                     |                              |
              |                     |                              |
              |                     |               C FINISHES     |
              |                     +         +<-------------------+
              |                               |
              |                 B FINISHES    |
              +          +<-------------------+
                         |          |
          A FINISHES     |          |
    +<-------------------+          |
    |         |                     |
    |         |                     |
    +         +                     +
  JOB 1
 CONTINUES