An input device is a medium that you can use to enter or input data into a computer:
Voice recognition devices
Output devices enable the user to see the results of the computer’s calculations or data manipulations.
Output devices include:
Computer screen/monitor/visual display unit
Mobile Phones Hardware
Character Keys - A-Z
Shift Key - To type text in uppercase (Help other functions eg F Keys)
Ctrl Key - Does nothing by itself, it must be used in combination with other keys to
change the normal effect of the key. (Helps with ‘Hot Keys’)
Alt Key – Also used in conjunction with other keys to change their function.
Ctrl+Alt+Del to log in)
Enter and editing Keys
Enter Key – Returns the cursor to the beginning of the next line, creates paragraphs,
also functions as a ‘go’ key.
Backspace Key – deletes words or spaces to the left of the cursor.
Delete Key – deletes words or spaces to the right of the cursor.
Insert Key – is a toggle key – either to allow insertion to the right of the cursor or
the type over existing type.
System and GUI Keys
Windows Key – brings up the windows start menu.
Menu Key – brings up dropdown menu. (same as a right click)
Escape Key – cancels actions in progress before they finish,
also closes certain dialogue boxes.
Print Screen Key – takes a screenshot of the monitor.
Pause Break Key – for use in the command prompt window.
Home Key – returns you to the beginning of the line.
Page Up Key – moves the cursor to the page above.
Page Down Key – moves the cursor to the page below.
End Key – moves the cursor to the end of the line.
Tab Key – moves the cursor to tab increments set on the tab line.
Arrows – navigation keys that move one line or one letter at a time.
F1 – Help Key
F2 – Renames a highlighted icon or file
F3 – Search feature
F4 – Repeats last action performed while typing in Word
F5 – Refreshes (updates) pages in the browser
F6 – Moves the cursor to writing web address at the address bar
F7 – Opens a spell checker
F8 – No assigned windows default
F9 – Opens the measurements toolbar
F10–Activates the menu bar in many programs
F11 – Sets to full screen mode in most programs
F12 – Saves documents in MS Word
When the num lock key is active it works as numeric keys
When the num lock key is inactive it works as navigation keys
Num Lock – is a toggle switch to turn numeric key pad on or off
Scroll Lock – toggle switch to lock scrolling in MS Excel
Caps Lock - toggle switch that allows you to type in uppercase without
having to hold the tab key down
Left Mouse Button
Tells the computer what to do by selecting one of the options it gives you
Right Mouse Button
Brings up dropdown/popup menus for short cuts
Scrolls the page up or down
The functions of the mouse is to:
Point – to move the mouse to a place or object on the screen
Click – to press the left or right mouse button once
Double click – press the left mouse button twice quickly
Drag – To left-click an object and hold the mouse button down while moving an object across the screen
Right click – to press the right mouse button once.
This is the device that links your computer and your telephone line. It allows your computer to connect to the internet
and send and receive information to users worldwide. Most modern computers and modems run through a router that sends
out a Wi-Fi signal which allows your computer and other electronic devices including smart phones, tablets and laptops to
access the internet without a physical connection.
Used to convert text, drawings or photographs into a digital image. Scanned images can be saved, edited and printed.
CD/DVD-ROM (Optical device)
CD-ROM is an acronym for ‘compact disk read – only memory’ This reads information from a CD or DVD using a low powered laser.
Most modern CD/DVD ROM/Writers can both read and write information to a disk although this method of data storage is quickly
The hard disk is a magnetic device used as external memory for computer data or programs.
The hard disk is divided into tracks, sectors and cylinders. Its memory space is measured
in megabytes and gigabytes and terabytes.The hard disk can save much more data and retrieve
data more quickly than a disk. Many hardrives are still optical drives but this is slowly changing
and manufacturers like Apple are moving to stationary drives. They are quicker and more stable.
Flash drives can store a lot more information than a CD/DVD drive and is much quicker since the in
information can be retrieved quickly. They are also known as stationary drives since they are totally
digital, they do not need to mechanically spin up like a DVD/CD Drive. Included in this section are
External Drives, and external drive is similar to a flash drive but it can store a lot more data.
At this stage a 64GB flash drive is common place but external drives can store in excess of 1TB of information.
Printers produce paper copies, called hard copies. Printers are divided into two types, namely impact and non-impact.
Non-impact printers do not make physical contact with the paper, eg: Laser printers and Ink-jet printers
A laser printer puts images into a rotating drum by means of a laser beam.
It has few moving parts and is quieter and faster than an impact printer.
They are generally expensive but save time and increase efficiency.
The print quality is high and it can usually print text and graphics in a variety of fonts and colours.
This printer obtains its ink from black or colour cartridges, although it’s less expensive than a laser printer to purchase,
it prints far less copies from each cartridge. The copies are high quality but not as good as that of the laser printer.
Central Processing Unit
The central processing unit is a tiny electronic chip installed on the motherboard of the computer.
The CPU can be seen as the ‘brain’ of the computer. It co-ordinates and supervises the operation of the input, memory,
output and arithmetic logic unit. Without a CPU a computer cannot operate or even start up.
The CPU consists of the following parts:
The control unit controls the input and output devices, the loading and saving of data to and from the memory,
and the flow of information between the main memory and the arithmetic logic unit.
Arithmetic Logic Unit(ALU)
The arithmetic logic unit performs the computer’s arithmetic calculations such as addition, subtraction, multiplication
and divisions as well as comparisons.
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