Inside the World of Computing

3Software

3.1. Introduction

In the preface to this book, we mentioned the triangle representing the pillars of information technology. Chapters 1 and 2 dealt with two of these pillars: computer hardware, on the one hand, and means of communication, on the other hand. This is the third pillar, probably the most important, because the concepts of algorithm and software are at the heart of computing.

A computer system is a set of hardware or software components, put together to collaborate in the execution of an application.

A computer system can be described as a stack of layers, each one resting on the underlying layer and providing new and more elaborate functions. Adapted interfaces allow these layers to communicate with each other.

Figure 3.1 is a simplified representation of a computer system.

Figure 3.1. Computer system

Hardware is composed of processors, memories, disks and peripheral units (screen, mouse, printer, etc.). The operation of the hardware is based on instructions composed of only 0 and 1, and is said to have the lowest layer of abstraction at the hardware level.

The operating system (the core and utilities that provide basic services to the user) is the central element of the system. This layer will support the communication between applications and hardware, and ensure the execution of the instructions it has received from the application. Special languages ...