THE COMPUTER

A computer is defined as an electronic device, which accepts, processes and store data for later use or sends out data as information.

TYPES

• embedded

• mobile computer

• Personal computer

• mainframe Computer

• Supercomputer

ADVANTAGES OF USING A COMPUTER

• Consistency and accuracy of the results provided

• Enhanced storage

DISADVANTAGES OF USING A COMPUTER

• the initial set up cost is high

• easier for security and integrity of data to be compromised

HARDWARE

Hardware is any part of the computer that has physical structure, including the computer’s internal parts.

All computer systems need hardware to carry out the following four main processes:

• Accepting Input

• Processing that Input

• Producing output information

• Storing data and/or information for later retrieval and use

NOTE

• Input- The act of accepting data form the outside world

  Input device - a device responsible for getting data into a computer

• Processing- The act of transforming data into information that will be useful to the user

• Output- The act of presenting information to the user

  Output device- get processed data out of the computer

• Storage- The act of holding data, program instructions & information for later use.

• Memory enables a computer to temporarily store instructions and data

THE CENTRAL PROCESSING UNIT (CPU)

This is the brain of the computer it manages and orchestrates how the computer functions it consists of the CU & ALU

CU - executes software instructions and guides data flow

ALU- responsible for all calculations and logical operations

!!Peripheral devices- located outside the CPU but controlled by it.!!

WHAT IS PRIMARY STORAGE?

This is the component of the computer that holds data, programs and instructions that are currently being used.

WHAT IS SECONDARY STORAGE?

Secondary storage includes non-volatile devices for storing data outside of a computer's main memory (RAM).

MAIN MEMORY

RAM (random access memory)

a type of computer memory that serves as the short-term working memory of a computer

• Dynamic RAM

• Static RAM

CHARACTERISTICS

• Volatile (data is lost when power is lost)

• Larger in Capacity

• Temporary

• Faster and expensive

ROM (Read Only Memory)

• PROM-Can only be modified ONCE by the user

• EPROM-Data can be erased using ultraviolet rays and can be reprogrammed

• EEPROM- Data can be erased and reprogrammed repeatedly by applying an electrical voltage that is higher than normal. (over 10k times)

CHARACTERISTICS

• Non-volatile (data is lost when power is lost)

  Small Capacity

• Slower but cheaper

WHAT IS STORAGE UNIT?

A unit of measure used to show how much info can be saved and kept on a computer.

• 8 bits = 1 byte

• 1024 bytes= 1 kilobyte

• Nibble = ½ a byte

CLOUD STORAGE

• The process of storing data in an online space that spans multiple servers and locations, and it is usually maintained by a hosting company.

• People pay these companies to keep their data on servers and give them access to it anytime once they have internet connection.

• Examples: Google drive and Icloud

LOCAL STORAGE

• the process of storing digital data on physical storage devices (hard disk drives and external storage devices)

SOFTWARE

Software is a program that is executed by the hardware of the computer

TYPES - System software Application programs

SYSTEM SOFTWARE- used to operate and maintain a computer system includes the

• operating system

• utility programs

• language translators

OPEERATING SYSTEMS

• A set of programs that governs the operation of the computer.

• 6 primary functions (usfrmp)

  • User Interface- This is the point at which human user interact with a computer.

    • Types of user interface

      • Graphic user interface

      • Hardware interface

      • Software interface

      • Command driven

      • Menu-driven interface

  • Security Management- maintains a secure computing environment.

  • File Management - manages files and folders.

  • Resource Management- manages storage devices, input & output devices.

  • Memory Management- manages memory.

  • Process Management- manage processor resources.

• Examples are MacOS, IOS, Windows

SYSTEM UTILITY

• a specialized program that assists in maintaining and improving the efficiency of a computer system.

  • Back up

  • Defragmenter - reorganize

  • Disc error checker

  • Disc cleanup

  • Antivirus

  APPLICATION SOFTWARE NEEDS TOUCH UP

• Programs that help the user perform specific ask

• GENERAL PURPOSE: These are software that are not specific to anyone organization or business and can be used by anybody. For e.g.: Word, database, PowerPoint, Canva

• Customized software: general purpose software that has been modified to perform specific task for user.

• Custom Written: Also known as TaylorMade is written for use in specific organization.

• SPECIALIZED SOFTWARE: This is software that is designed for specific need or task. For e.g.: A camera on your device

DATA

• Raw unprocessed facts

  • Raw facts

  • no context

  • Plain numbers, text, etc.

INFORMATION

• meaningful knowledge derived from raw data.

• Data that has been processed/organized in a useful way

  • Processed data

  • data with context

  2 types of sources

• Thing that has been measured eg temperature | 28

• Person or organization that provided the data from observation.

Source documents are documents that contains data for input into an information processing system.

• Human-Readable Document

  • This is a document that can be read naturally by humans. It is not in a form that the computer can readily accept.

• Machine-Readable Document

  • This is one that can be readily process be the computer. E.g. items within barcode

• Turn-Around Document

  • This is a computer-generated form that is fill out, sent out and returned to the computer.

VERIFICATION

This is double checking for error with data that has already been entered.

Good verification significantly reduces the number of

• Typographical errors (missing or extra letters)

• Transposition errors (switching the position of 2 adjacent characters in a text)

Type of verification

• Proofreading- a data entry clerk visually checks the source document against data that has already been input by another entry clerk.

• Double data entry- when data is entered twice for comparison.

Validation

A checking process in a program which is aimed at finding out if the data entered is genuine

Type of validation

• Data type check

• Presences checks

• Check digit.

• Range check

• Consistency check

• Length check

• Reasonableness check

• Format check

NEW SHIT

COMPUTER SECURITY 

What is Computer Security? 

Computer Security is all the activities related to the identifying, assessing and managing vulnerabilities, threats and attacks on a computer system. 

Elements of Computer Security 

Computer security has FOUR (4) main elements: 

1. Vulnerability

Exposure to the possibility of being harmed or attacked 

2. Threat

A statement of intention to harm 

3. Attack

Actual action that causes damage or harm

4. Countermeasure

An action taken to counteract a threat 

What is Computer Misuse?

 This is any activity during which a computer system or network’s data  is accessed,  modified or deleted without proper authorization.

Computer misuse includes acts which are likely to cause unauthorized modification, removal or copying of the contents of any computer system, Directly or indirectly obtaining computer service without proper authorization, Accessing programs or data on a computer with the intent to commit a crime or just unauthorized access to a computer system.

Computer Misuse Affecting Individuals 

1. Cyberbullying:

Cyberbullying is a form of harassment or bullying in an online space.  It can occur through SMS or online gaming platforms. Cyberbullying includes insulting , false, harmful or mean comments or the sharing of embarrassing content. 

2. Identity Theft: 

Identity theft is the deliberate use of someone else's identity, usually to gain a financial advantage

Your identity can be stolen to do a number of crimes

including:

• False applications for loans and credit cards

• Fraudulent withdrawals from bank accounts

• Fraudulent use of online accounts

• Fraudulently obtaining other goods or services

3. Phishing Attacks:

Phishing involves attempting to steal sensitive information (like usernames, passwords, or credit card details) through fake emails pretending to be from trusted organizations. Users are usually asked to click on a link and promised  a reward. 

4. Violation of Privacy: 

Privacy refers to the right of individuals to decide freely under what conditions and to what extent they will disclose personal information about themselves. Governments and organizations that handle personal data, such as names, addresses, birth dates, bank details, and contact numbers, are responsible for maintaining its confidentiality. Violations of privacy occur when any of these rights are breached, including storing inaccurate personal data, sharing information without the individual's consent, or using data for purposes other than those originally intended.

Privacy policies outline how the data that websites collect will be used and what rights the  user is giving up when they accept the website’s terms of service

Computer Misuse Affecting Organisations

1. Copyright Infringement  & Software Piracy 

Copyright infringement occurs when someone other than the rights holder reproduces, distributes, or benefits from the work without permission or paying required fees.

Software piracy is the unauthorized reproduction, distribution or use of software products. Software piracy negatively impacts the legal owners that produce the software because it reduces their revenues. It also harms national and regional economies. A lower number of legitimate software sales results in lost tax revenue.

2. Data Theft 

Data theft is the unauthorized copying or removal of data from the legitimate owner’s computer System.

The Dark Net  is the term given to the parts of the Internet that are kept hidden from the general public and cannot be accessed by standard search engines such as Google and Bing.

3. Denial of Service Attacks (DOS) 

 A denial of service attacks (DOS attack) is a cyber-attack where the intent is to prevent a service being delivered by the target system.

The attack could be by an individual hacker exploiting a vulnerability in the target system to gain unauthorized access and so crash the system from within.

NB. When the attack is directed from the outside in, it may be a distributed denial of service attack.

4. Malware

Malware (malicious software) is software designed to disrupt, damage or gain unauthorized access to a computer system.

Malicious programs can be delivered:

• Physically

• Via the Internet 

• Via phishing attacks

Computer Misuse Affecting Governments 

1. Electronic Eavesdropping 

Electronic eavesdropping is the act of electronically intercepting communications without the knowledge or consent of at least one of the participants.It is used by both law enforcement and criminals. 

2. Propaganda 

Propaganda is communication of information that is of a biased or misleading nature and that is aimed at influencing the recipient. The content is usually repeated and dispersed over a wide variety of media

What is Cybersecurity?

Cybersecurity is the body of technologies, processes and practices designed to protect networks, computers, programs, and data from attack, damage or unauthorized access

Cyberspace:  A Cyberspace is any data or resources that are accessed through a network or internet operated space. 

Cybercrime:  Cybercrime is any crime perpetrated using computers and networks

Countermeasures To Mitigate Threats

Physical Measures, Software Measures and Personal Security Practices can be used to mitigate threats

Physical Measures

A physical security measure is any mechanism that reduces the risks of unauthorized  access to a computer system’s hardware

Software Measures

Software countermeasures are a combination of specialized system software and application software used to protect computer systems.

Personal Security Practices

Personal security practices are countermeasures used by individuals to implement computer security and cybersecurity.

Problem Solving 

What is a Problem? 

In Information Technology, a problem is a discrepancy (or difference) between the data we have and the information required. 

Problem Solving Terms 

Solution:  A solution is a set of instructions that, if followed in order, will produce the required information.

Problem Solving:The process of creating a set of instructions that, when executed, is solving a problem that was indicated previously.

Pseudocode: Pseudo code is a formal way of writing an algorithm using structured English text, numbers and special characters.

Flowchart: A flowchart is a pictorial way of representing an algorithm using a set of standard symbols (shapes)

Steps in Problem Solving 

1. Define the problem

2. Propose and evaluate solution

3. Determine the best solution

4. Develop the algorithm

5. Represent the algorithm as pseudocode or a flowchart

6. Test and validate the solution

 IPO Charts

An input-Process-Output (IPO) chart is a helpful diagrammatic way to start breaking down a problem. 

Variables & Constants 

The IPO chart stores values: VARIABLES & CONSTANTS

In programming, a variable is a container that stores values capable of changing during processing .

A constant is also a container with a value, but that value cannot be changed during processing.

N.B  All variables and constants have an identifier and a data type 

Identifiers E.g  5 → (num1)  September → (birth month)

Data Types 

• Integers: Whole numbers such as 1, 5, -7, etc 

• Float: Numbers which are not whole (decimals, fractions)

• Character: letters,  numerical values and special symbols such as @, b, 7 (single)

• String: a SEQUENCE of characters (whole words, tele #) eg, boy, (8766)

• Boolean: a true or false value (YES/NO)

Before use in a program they must be declared. This allows the computer to allocate the correct amount of memory to hold the values.

 Algorithms 

An algorithm is a sequence of instructions which rigorously defines a solution to a problem.

All algorithms are:

1. Unambiguous -not open to more than one interpretation.

2. FInite -must eventually finish.

3. Precise - They have instructions that pass the flow of control from one process/action to another.Instructions in an algorithm must be followed in a sequence, control passes from one process to the next until the algorithm terminates

EXAMPLE OF A SIMPLE ALGORITHM 

START 

DECLARE NUM1, NUM2,  sum as INTEGER

PRINT “Please enter the first number” 

READ NUM1

PRINT “Please enter the second number” 

READ NUM2

sum = NUM1 + NUM2

PRINT “The sum is”, sum 

STOP 

Relational Operators 

Relational operators test the relationship between two values in a condition and always result in true or false.

A condition is an expression that includes a relational operator and the two operands on which it

operates.

An operand is a data value, held in a variable that is part of a condition.

Arithmetic Operators 

These are symbols that represent mathematical computations such as addition, subtraction, multiplication and division.

• + (Addition)

• - (Subtraction)  

        ? ( Multiplication) 

          / (Division) 

SPECIAL ARITHMETIC OPERATORS:  

DIV: DIV is the integer division operator which discards the fractional part (remainder) of

the results.

For example 5 DIV 2 since the remainder, which is 1, is discarded.

MOD:    The integer remainder operator which gives the fractional part (remainder) of the result.

For example 5 MOD 2 produces 1 since this is the remainder.

Conditional Branching

The performing of actions based on specific situations or conditions 

Conditional Branching Statements 

IF-THEN  

The instruction(s) within the IF statement will be executed once the condition is

TRUE. If the condition is not met or it is FALSE, the instruction(s) within the IF statement will be ignored.

IF-THEN -ELSE

The  first condition is checked.  If the first condition is met, the instruction(s) within the statement will be executed. The second condition will be ignored, seeing that the first condition is already

TRUE.

If the first condition is false, the second condition is checked. If the second condition is TRUE:

The instruction(s) within the statement will be executed.

NESTED CONDITIONS 

Conditional statements within or grouped with other conditional statements. The aim of is to check if multiple events or data is TRUE before executing the instruction(s).