Introduction to Computers
Objectives By the end of this lesson, you should be able to: State and explain various physical parts of a computer
Physical Parts of a Computer
Keyboard - it is a keying input device used to enter data into a computer
system unit - this is the box-like casing that houses the CPU and the motherboard together with other electronic components. System units are of two types namely:
Mouse - is a pointing input device used to move the pointer on the screen and also used to execute commands by pressing its buttons
Monitor - used to display results of information processing (output) and running programs.
Peripheral devices - refers to the physical devices connected to the systems through ports e.g printers, speakers, flash disks, keyboards, monitors
Objectives By the end of this lesson, you should be able to: Define a computer Differentiate between data and information Explain the unique characteristics of computer as a data processing tool
Definition of a computer
Data refers to raw facts without much meaning to the user while information refers to the processed data that is meaningful to the user
Software refers to a set of instructions that guides the computer on how to perform a given task
Characteristics of a Computer
1. Fast: A computer can perform calculations within seconds that human beings would take hours to complete
2. Accurate: A computer has a high degree of accuracy regardless of the complexity and number of times a calculation is performed. Errors may occur due to data inconsistency and inaccuracy
3. Versatile: Can be used to carry out different tasks with the same accuracy and efficiency such as playing games and performing calculations
4. Reliable: computers work for many years without any problem
5. Diligent: A computer can perform repetitive tasks without getting bored, tired, fatigued or losing concentration
6. Vast Storage Capacity: computers have inbuilt memory used to store and retrieve large amount of data
By the end of this lesson you should be able to: Classify computers according to their physical sizes
Classification of Computers Lesson I
Classification According to Physical Size
Supercomputers
It is the largest, fastest and most expensive. Used for scientific research and forecasting which involves a lot of calculations.
Characteristics
Mainframe Computers
Less powerful compared to supercomputers but more powerful than minicomputers. The main difference between mainframe and supercomputers is that supercomputers channel their power into processing a few programs as fast as possible while mainframes channels their power into processing many programs simultaneously (parallel processing).
It supports many concurrent users
It is mainly for commercial applications i.e handling daily transactions and batch data processing
Characteristics of mainframe computers.
Minicomputers
It is less powerful than the mainframe but more powerful than microcomputers. It is smaller in size compared to a mainframe computer.
Microcomputers
They are the smallest, cheapest, and least powerful. Examples are Desktop, laptops, tablets, smartphones, and smartwatches
Microcomputer is the smallest, cheapest and relatively least powerful type of computer. The term microcomputer evolved from the word microprocessor which is the brain of a micro-computer.
NB: The above-mentioned microcomputers are arranged in descending order according to size.
Advantages of laptop computers
Disadvantages of laptop computers
The image below is a supercomputer
By Trower, NASA: Supercomputer
By the end of this lesson, you should be able to:Classify computers according to purposeExplain each of the category of computers above
Classification of computers according to purpose
According to purpose, computers are classified as:
General Purpose Computers
These refer to computers capable of performing a variety of tasks since they can store and execute different programs.
Special Purpose Computers
These are computers designed to perform a specific task. For example, a play station is used for playing graphic-intensive video games
Special-purpose computers are designed to serve a particular purpose or accomplish one particular task. Such computers can perform no other task except the one they were meant to do.
Example
NB: Mobile Phones and calculators are also classified as special-purpose computers because they were made to perform one major task. i.e. phones meant for communication only and electronic calculators to carry out calculations only
Dedicated purpose computers
These computers are designed to perform a wide variety of tasks though they are committed to some processing tasks. I.e. the computer can be dedicated to carrying out word-processing tasks only.
By the end of the lesson, you should be able:Classify computers as either digital , analog or hybrid.
Classification of computers according to functionality
According to functionality computers are classified as:
Analog computers
These are computers that process data that is continuous in nature. Examples of continuous data are variations in physical quantities E.g. temperature, heart beats humidity etc
Digital data is represented using values that do not have any transitional changes over time.
NB: This means that the data is processed at a very high speed and within no time the output is provided to the user.
The data is said to be discontinuous because one task must be accomplished so before starting the other task. i.e. Each letter typed using a microcomputer is converted into digital form and displayed on the screen after processing operations at a time.
Analog data/continuous data is represented using values that have transitional changes on time.
NB: This indicates that analog data take time to process as compared to digital data.
Digital Computers
These computers process data represented in terms of binary digits. The data processed by these computers are discrete.
Hybrid computers
Processes both analog and digital types of data.
Examples
Public Domain, Calculator, Special Purpose Computer
Objectives By the end of the lesson, you should be able to: Describe the historical development of mechanical computer
Historical Development of Computers
The first computers were people. However, due to the complexity of tasks, mechanical computers and electromechanical computers emerged. Examples of mechanical computers included: Abacus(Chinese and Babylonians), Napier's Bones (Scottish Mathematician, John Napier), Slide Rule(William Oughtred), Pascaline Machine(Blaise Pascal, French Mathematician), and finally Charles Babbage Invented the analytical and Difference engine.
After mechanical computers, electronic computers emerged. Examples Mark I, ENIAC, UNIVAC, EDSAC, PDP-1, Z-3, IBM 1400, IBM,360, Altair 8800, Honeywell
The first electronic computer was the Electronic Numerical Integrator and Computer
Electronic computer generations are divided into five :
First Generation (1940-1956)
The remarkable features were:
Second Generator(1956-1953)
The remarkable features were:
Examples of 2nd Generation computers:
Examples of computers developed in this generation included: PDP-1, IBM 1400
Third Generation(1964-1971)
Features
Examples included: PDP-8 and IBM 360
Fourth Generation(1971-1990)
Examples of 4th Generation computers:
Examples Altair 8800
Fifth Generation (1990-Present)
In this generation fall today’s computers.
The technologies used Parallel architectures, 3-Dimensional circuit design & superconducting materials. These technologies have led to the development of computers referred to as Supercomputers, which are very powerful, and have very high processing speeds. Their speeds are measured in Nanoseconds & Picoseconds.
They are able to perform parallel (or multi-processing) whereby a single task is split among a number of processors.
The memory sizes range between 1 Gigabyte & 1 Terabyte or more.
The computers are designed using VLSI and the Microchip technology that has given rise to the smaller computers, known as Microcomputers used today.
The computers have special instruction sets that allow them to support complex programs that mimic human intelligence often referred to as Artificial Intelligence. Such programs can help managers to make decisions and also provide critical expert services to users instead of relying on human professionals.
Objectives By the end of this lesson, you should be able to: Define computer laboratory State the factors that should be considered when setting up a computer lab State and explain measures to protect the computers and computer users
Definition of a computer laboratory
A computer laboratory is a special room set aside for the safe installation and use of computers
Factors to consider when setting up a computer laboratory:
Safety precautions and practices
Measures that protect the computer user
Measures that protect the computer
By the end of this lesson, you should be able to:Define bootingDifferentiate between cold and warm bootingDescribe the booting processDemonstrate the starting of a computerDemonstrate the steps of shutting down a computer
Booting a computer
Booting refers to the overall processing of making a computer ready for use
Types of Booting
Cold Booting
This refers to starting a computer that was off initially by pressing the power button
Warm Booting
This refers to the processes of restarting that was initially on by clicking on the restart button
Booting process
Once the computer is turn on, the BIOS checks the input and output hardware if they are in a good. This is known as Power On Self Test.If there is no problem encountered during this process, the Operating System is loaded onto the RAM and takes over the control of the computer. Note that during the booting process the computer also reads the correct time from the CMOS memory. If the battery for the CMOS memory has worn out, the computer prompts the user to enter the current date and time every time a the computer starts.
Shutting down a computer
If the Operating system is windows 10.
By the end of the lesson, you should be able to:state and explain various categories of keys on a computer keyboardGive examples of the above categoriestype while observing the typing guidelines
Keyboarding Skills
Categories of keys on a computer keyboard
Typing(Alphanumeric) keys
These are A-Z and 0-9
Function Keys
These are F1-F12
Cursor movement Keys
Editing Keys
Special purpose keys
Used together with other keys to issue specific commands to a computer
They include:
Numeric keypad keys
They are used when Num Lock is turned on
0-9 and arithmetic keys
Typing Guidelines
Left hand home keys
Right hand home keys
By the end the lesson you should be able to :Perform the four mouse operationsDefine the four mouse operation terminologies
Mouse Skills
Guidelines for using a mouse
Common Mouse Operations
Clicking - Pressing and releasing the left mouse button once. This operation is used to execute commands and select icons
Double-clicking: Pressing and release the left button of the mouse twice in quick succession. This operation is used to open a folder or a file or to launch an application
Right-Clicking - This refers to pressing and releasing the right button of the mouse once. This operation is used to display a context menu.
Drag and Drop - It is where the user points to an icon, hold down the left button of the mouse and drags the icon to the next location, and releases the button.
By Donald Trung Quoc Don, Computer Mouse