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Data Representation in a Computer

Introduction Data Representation in a Computer

To define data and information

Introduction Data refers to a collection of raw facts, figures or instructions that do not have much meaning to the user Information refers to data which has been manipulated into a more meaningful form Information is stored in a computer inform of binary digits(bits) which takes two states i.e. either 1(on) or 0(off). Computers use binary digits to represent everything. That means that whatever you store in a computer must be expressed as a binary pattern of ones and zeros. Take a simple integer, 27. In binary code, this number is actually 110112, each digit referring to a power of two

DEFINITION OF TERMS USED IN DATA REPRESENTATION IN A COMPUTER

To define various terms used in data representation

  • Bit -  a binary digit which can either be 0 or 1 
  • Byte A group of 8 bits used to represent a character e.g. 110110012 is one byte.
  •  Nibble A group of four binary digits i.e. half a byte 
  • Word Made up of two or more bytes. 
  • A word may have a word length of 16bits, 32bits, 64bits, e.t.c.

Data Signals

To describe various types of signals

It is the voltage level in a circuit which represents the flow of data Signals can either be analog or digital in nature 

ANALOG SIGNAL 

It is a signal made up of a continuous varying waveform It rises to +1 and falls to -1 in a continuous manner 

DIGITAL SIGNAL 

It is made up of a non-continuous discrete signal

AMPLITUDE,FREQUENCY ,PERIODIC TIME,WAVELENGTH

  • To define :amplitude,frequency,periodic time and wavelength 
  • To describe data representation in a telephone line

A wave is described using the following terms 

Amplitude (A); It is the maximum displacement that an electrical signal can attain. In the above example the amplitude is one. 

Frequency (F); It is the number of cycles made by a signal per second i.e. how many waves per second.  It may be measured in: Hertz 1 Hz means 1 wave per second, Kilohertz 1 kHz is 1,000 waves per second, Megahertz 1 MHz is 1 million waves per second.  Gigahertz1 GHz is 1,000 million waves per second. 

Periodic Time; It is the time taken for one complete oscillation. 

Wavelength; means the length of one wave i.e. the distance from any point on a wave to the same point on the next cycle of the wave. It can be measured in Km, m , cm, e.t.c

DATA REPRESENTATION ON A TELEPHONE LINE 

Digital signals are unable to travel across traditional analogue telephone wires. To transmit digital signals across telephone lines, the signals need to be converted to analogue signals. Signal modulation is the conversion of digital signals to analog signals for transmission over analog media. Signal demodulation is the conversion of analog signals back to digital signals on the receiving end. Signal modulation and demodulation is performed using a device known as modem. It is a modulator and demodulator i.e. it convert digital signals to analog signals for transmission over telephone lines. On the receiving end it converts the analog signals back to digital signals.