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System Software Avinash Bhagat, Lovely Professional University

Notes Unit 11: Programming Languages Concept (II)

CONTENTS

Objectives
Introduction
11.1 Functional Modularity
11.1.1 Advantages of Modular Approach
11.1.2 Top-down Approach

11.1.3 Bottom-up Approach
11.2 Asynchronous Operation
11.2.1 Beginning an Asynchronous Operation

11.2.2 Ending an Asynchronous Operation
11.2.3 Asynchronous Operations Conditions and Signals
11.3 Multitasking
11.4 Summary
11.5 Keywords

11.6 Review Questions
11.7 Further Readings

Objectives

After studying this unit, you will be able to:

 Understand the concept of functional modularity
 Discuss asynchronous operations
 Understand multitasking

Introduction

The real power of partitioning comes if a system is partitioned into modules so that the modules
are solvable and modifiable separately. In this unit you will understand the concept of
modularity. Also you will study the concept of Asynchronous Operations. Lastly we will discuss
how to execute multitasking.

11.1 Functional Modularity

A system/program is considered modular if it consists of direct modules so that each modules
can be separately implemented, and a change in one module has minimal impact on other
modules. Before we discuss it in detail, let us define what we meant by a module.
A module is a logically separable part of a program. In other words, a set of related procedures
with the data they manipulate is called a module. In terms of common programming language
construct, a module can be a macro, a function, a procedure, a process or a package. It is based on
the following principle:

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