HP 3000 Manuals

Process Management Programmer's Guide

What is a Process? 

A process is the basic executable entity in the MPE XL operating system.
When you enter the following command:

     :RUN PROGNAME.PUB.MYACCT

you are directing MPE XL to create and manage a process that executes the
code found in your program file PROGNAME.

A process, then, can be described as a program and its environment.  The
program consists of re-entrant and shared executable code.  The
environment, created and managed by MPE XL, includes all resources that
the program may reference or use that are exterior to the program.
Resources may be main memory, I/O devices, and even other processes.  In
addition, MPE XL must keep a record of the current state of the process
and what is currently in the environment.

Process Components 

A process in the MPE XL operating system consists of sharable executable
code, a private data area available to the process, and a data structure
commonly referred to as a process control block that defines the process
and contains pointers to information required for process management (see
Figure 1-1).

Process Identification 

MPE XL assigns each process a unique Process Identification Number (PIN)
when the process is created.  Both you and the system can use the PIN to
identify a process throughout its life span.  When the process is finally
deleted from the system, the PIN is released, and can be used again to
identify another process.


          Figure 1-1.  MPE XL Process Components 

MPE/iX 5.0 Documentation