A process exists in different states according to its past and present status
and its present requirements for system resources. MPE/iX allows the user some
control over a process' movement between three of these states.
A process in a suspended state is not allowed control of the CPU until it receives an activation signal from a system intrinsic. When it suspends
itself, a process must specify the process or processes that are permitted to
reactivate it.
A process in an active state is scheduled to gain control of the CPU
(awaiting its turn to enter an executing state).
A process in an executing state has control of the CPU. It leaves this
state when it has used up its scheduled quantum of time (it enters an active
state), when it is blocked or pre-empted by an interrupt, when it suspends
itself (it enters a suspended state), or when it is deleted from the system.
During its life span (that is, between creation and deletion), a process
progresses through these states in response to the following:
The instruction sequence found in the program code
The actions of other processes
