.. _p_contents:

Process Contents
=================

* An address space
* A program
* A execution engine (program counter, ...)
* Data
* Resources
* Process control block (PCB) with process identifier (PID)

A Classic Process (one thread)
---------------------------------------

.. figure:: process.png
   :align: center

   A process is not an executable program, but rather a running instance of
   a program.

The Address Space
------------------

.. figure:: address_space.png
   :align: center

   Each process views its memory as a contiguous set of logical memory
   addresses.  The operating system manages the translation of logical
   addresses to the physical memory addresses of the computer.

.. _pcb:

Process Control Block (PCB)
----------------------------

The :term:`process control block` is a data structure for each process
holding:

* Register values
* Logical state
* Page map table mapping logical addresses to physical addresses
* Type & location of resources it holds
* List of resources it needs
* Parent process identification
* Security keys
* etc.