This document defines the key elements of a computer system. It distinguishes between hardware and software, with hardware being the physical components like disks and chips, and software being programs like operating systems. It describes the basic components of a computer as including input devices, output devices, storage devices, a central processing unit, and main memory. It also explains the fetch-execute cycle that computers use to process instructions, with fetch, decode, and execute as the three main stages.

1. Elements of a
Computer System
Understanding Computers

2. Understanding Computers
L1 – Elements of a Computer
Elements - Learning Objectives
• All will be able to distinguish between
hardware and software and identify Input,
Output and Storage devices
• Most will be able to explain what RAM and
ROM are used for and distinguish between
main memory and permanent storage devices
• Some will be able to name and explain the
three stages in the Fetch Execute Cycle

3. Understanding Computers
L1 – Elements of a Computer
Hardware or Software?
What is Hardware? What is Software?
Objects that you can touch, like
a Music CD. For example:
Disks, disk drives, display
screens, keyboards, printers,
boards, and chips.
You cannot ‘touch’ software.
Software refers to the
programs that run on a
computer, rather like the music
playing on a CD.
Examples of software:
Windows, MS Word, MS Excel,
Kodu and Logo.

4. Understanding Computers
L1 – Elements of a Computer
Input, Output & Storage Devices
What is an
output device?
What is an
input device?
What is a
Storage device?
An output device is
a piece of computer
hardware used
display or output
data which has been
processed or stored
in a computer.
Printer, Speaker.
An input device is
anything can be
used to enter data
into a computer.
Keyboard, Mouse.
A storage device is
used to permanently
record or store data.
CD, Hard Drive.

5. Understanding Computers
L1 – Elements of a Computer
What do each of these images represent? Are they hardware or software?
Input, Output or Storage devices?

6. Understanding Computers
L1 – Elements of a Computer
Components of Computer
Hardware
INPUT
DEVICE
OUTPUT
DEVICE
PROCESS
DEVICE
STORAGE
DEVICE

7. The Central
Processing Unit
(CPU)
Understanding Computers

8. Understanding Computers
L1 – Elements of a Computer
What are these Components?

9. Understanding Computers
L1 – Elements of a Computer
The Components of a Computer
Central
Processing
Unit
(CPU)
Input
Output
Main
Memory
Storage

10. Understanding Computers
L1 – Elements of a Computer
Fetch – Decode – Execute Cycle
Decode
Execute
Fetch

11. Understanding Computers
L1 – Elements of a Computer
Fetch – Decode – Execute Cycle
• Computer has a list of instructions in memory
to carry out.
• CPU Fetches top instruction from the list
• Instructions is passed to Decoder to interpret
• Decoder passes on the instruction
• Instruction is Executed or carried out
• CPU Fetches top instruction from the list…