The components of an Information System - Introduction

Many people mistakenly call the system unit the “CPU”. The CPU is inside the system unit.

 HARDWARE is the term used to describe the parts of a computer that can be touched and handled.  SOFTWARE is the term used to describe the programs that allow the hardware to perform tasks.

 HARDWARE is also the term used to describe the devices that make up a computer system.  These are:  Input devices  The central processing unit  Backing storage  Output devices

Central processing unit (CPU) Backing store Output devices Input devices A simple computer system

 Computers are fast.  Computers are accurate.  Computers can store large amounts of information in a very cheaply in a small space.  Computers can work 24 hours per day, every day.  Computers can do work that would otherwise be impossible.

 A computer can perform over several million calculations per second.  Computer speed is measured in Hertz. One hertz = one calculation per second. ▪ 1 KHz = 1024 calculations per second ▪ 1MHz = 1024 KHz (over 1 million calculation/sec) ▪ 1GHz = 1024 MHz (you do the maths!)  Most modern computers have a speed of around 3GHz now!

 If given the right input, computers will always produce the right output.  However, if given incorrect inputs a computer will produce incorrect outputs.  This is called GIGO – garbage in, garbage out!

 The cost of administering and maintaining a three draw filing cabinet is estimated to be £2,700 per year.  The cost of a CD-R that could store the same information electronically is £0.10.

 Computers don’t need meal breaks, become ill, have holidays, or go on strike.  Human beings need meal breaks, become ill, have holidays, and can go on strike.  That said, there are some jobs that humans can do that computer can not.

 Computers can be used to design aircraft and cars, and then test the designs. This saves time and money.  Computers can be used to model what happens inside volcanoes so that they can be studied. This would be too dangerous for a human to do.

 Computers can replace people in certain types of employment.  Computers are not always secure, and confidential information can be misused.  Computers do not always work!  Staff need training to use computers.