Thursday, February 21, 2013

DATA STORAGE : DATA IN THE COMPUTER

Inside the Computer

STUDENT LEARNING OBJECTIVES

• To describe how data are stored in a computer system

• To demonstrate the relationships between bits, bytes, characters, and encoding systems.

• To understand the translation of alphanumeric data into a format for internal computer representation

• To explain and illustrate the principles of computer operations.

• To identify and describe the relationships between the internal components of a computer

• To distinguish processors by their word length, speed, and memory capacity.

DATA STORAGE : DATA IN THE COMPUTER

The three most basic questions encountered during one's computer learn­ing adventure are :

1. What is a computer?

2. What does it do?

3. How does it do it ?

In Previous topics address the first two questions By now you should have a good idea of what a computer is and what it does. This topic deals with the third question as we peek inside the computer to learn how it works.

Contrary to popular thinking, the internal operation of a computer is far more interesting than mysterious. The mystery is in the minds of those who listen to hearsay and believe science-fiction writers. The computer is a nonthinking electronic device that has to be plugged into an electrical power source, just like a toaster or a lamp.

The first step in learning what happens inside a computer is learning how data are stored. in Previous topics we learned that data, not information. are stored in a computer system. Data are the raw material from which information is derived . and information is data that have been collected and manipulated into a meaningful form. To manipulate data within a computer system, we must have a way to store and retrieve this raw mate­rial.

It is easy to understand data storage in a manual system. For example, when a customer's address changes, we pull the customer's manila folder from the file cabinet, erase the old address, and write in the new one. We can see and easily interpret data that are kept manually. we cannot see or easily interpret data stored in a computer. Data are represented and stored in a computer system to take advantage of the physical characteristics of electronics and computer hardware, not human beings.

Data are stored temporarily during processing in a section of the com­puter system called random-access memory (RAM). RAM was introduced and discussed briefly in Previous topics , "Computer Systems: Micros to Super­computers." RAM is also referred to as primary storage. Data are stored permanently on secondary storage devices such as magnetic tape and disk drives. We discuss primary storage (RAM) in detail later in this topics . Secondary storage is covered in previos topics , "Data Storage and Organization .

" In this topic we focus on the details of how data are repre­sented electronically in a computer system and on the internal workings of a computer.

Inside the computer-3_03