SS1 Computer Science First Term Lesson Note

 

OVERVIEW OF COMPUTER SYSTEM

Definition of a Computer
A computer is an electronic device that, under the control of stored programs, accepts data as input, stores and processes that data, and produces results as meaningful information.

Computer Performs Four Key Operations on Data

1. Input: Data are entered into the computer through input devices such as a keyboard, mouse, or scanner. These data are raw facts that the computer processes into meaningful information.
2. Processing: The computer performs operations on the input data. This task is carried out by the Central Processing Unit (CPU), which interprets instructions and processes the data accordingly.
3. Output: The processed results are presented through output devices such as monitors, printers, or speakers, making the information usable and understandable.
4. Storage: Both input data and processed information can be stored in the computer’s memory (temporary storage) or on permanent storage devices (such as hard drives, SSDs, or external media) for future use.

 

Constituents/components of a Computer System

The computer is referred to as a system because it is made up of several components that work together to ensure it functions properly. The two main constituents of a computer system are:

• Hardware
• Software

1. Hardware

Hardware refers to the physical components of the computer system. These are the tangible parts that can be seen and touched. Hardware is divided into two major categories:

a.       System Unit 

b.      Peripherals

a. System Unit: The system unit is the case that houses critical components responsible for the operation of the computer. Things within the system unit include

• Motherboard
• CPU (Microprocessor)
• RAM (Random Access Memory)
• Expansion cards such as sound cards and video cards
• Storage drives such as hard drives, CD/DVD drives, and (historically) floppy disk drives
• The necessary interfaces (ports) for connecting peripheral devices.

b. Peripherals: Peripherals are external devices connected to the system unit to enable input, output, and storage operations. Examples include:

• Input devices: Keyboard, mouse, scanner
• Output devices: Monitor, printer, speakers
• Storage devices: External hard drives, USB flash drives, DVDs, CDs

 

2. Software

Software refers to the collection of programs that can be run on a computer system. A program is a set of instructions that tells the computer what to do, how to do it, and when to do it.

There are two main types of software:

a.       System Software

b.      Application Software

a. System Software: System software controls the hardware and manages the internal operations of the computer system. It acts as a bridge between the user, application programs, and the hardware.

Examples include:

• Operating systems (OS): An Operating System is a type of system software that manages the computer’s hardware and software resources. It acts as a link between the user and the computer hardware, making it possible for applications to run.  Examples are Windows (XP, 7, 8, 10, 11), Linux (Ubuntu, Fedora, Red Hat), macOS, Android, iOS.
• Utility programs: Tools that perform maintenance tasks such as antivirus software, disk cleanup tools, and backup programs.
•  Translators: These convert programs written in high-level or assembly languages into machine code that the computer can understand. They include compilers, interpreters, and assemblers. Examples: GCC (C compiler), Python Interpreter, MASM (assembler).

 

b. Application Software: Application software enables users to perform specific tasks or operations on the computer. These tasks may be related to productivity, education, entertainment, or communication.

Examples include:

• Productivity software: Microsoft Word, Excel, PowerPoint
• Web browsers: Google Chrome, Mozilla Firefox, Safari
• Media players: VLC Media Player, Windows Media Player
• Graphics software: Adobe Photoshop, CorelDRAW
• Communication tools: Zoom, Microsoft Teams, WhatsApp Desktop

 

Some Application Software and Their Uses

 

Application Software (Packages)	Functions / Uses
MS Word, WordPad, WordPerfect	Used for word processing (creating, editing, and formatting text documents)
MS Excel, Lotus 1-2-3, Quattro Pro	Used for spreadsheets, calculations, and data analysis
CorelDRAW, Paint, Photoshop, PageMaker, Corel Graphics	Used for graphic design, drawing, and image editing
FrontPage, Publisher, Dreamweaver, ColdFusion	Used for web design and development
MS Access, Oracle, PostgreSQL, FoxPro, dBASE, Ingres, MySQL	Used for database creation and management
MS PowerPoint, Impress, Prezi, Harvard Graphics	Used for preparing and delivering presentations
MATLAB, SPSS, Minitab, Mathematica	Used for mathematical computations, statistical analysis, and scientific research
Internet Explorer, Mozilla Firefox, Google Chrome, Opera, Safari, Netscape Navigator, UC Browser, Mosaic	Used for web browsing and accessing the Internet

 

 

Data and Information

1. Definition of Data

Data refers to raw facts and figures that have not yet been processed to give meaning.

It consists of facts and values that is usually unorganized and are not yet meaningful until it is processed. On its own, it may not be useful. Data is the basic input for processing.

Types of Data and examples

Data can exist in different forms:

·         Numeric Data → Numbers (e.g., 120, 56.8).

·         Alphabetic Data: This are data that are made up of alphabets only (e.g. A – Z, Sex, Name, State)

·         Alphanumeric Data: These are data that is made up of a combination of alphabetic and numeric data (e.g. Peugeot 306, SS 1, 10^th March 1990)

·         Text Data → Words and letters (e.g., “School,” “Name”).

·         Audio Data → Sounds or voice recordings.

·         Video Data → Moving images and sound clips.

·         Image/graphic Data → Pictures, diagrams, or graphics.

·         Symbol Data → Special characters or icons (e.g., %, $, #, emojis).

Example: A list of phone numbers is meaningless until we know who they belong to.

2. Definition of Information

·         Information is the result of processed data that is organized and meaningful. Information carries meaning that can be understood, making it useful for decision-making.

·         Example: “The average score of the class is 64%” is information derived from the raw scores.

Qualities of Good Information

For information to be truly valuable, it must have these qualities:

·         Accuracy: It should be correct and free from errors.

·         Relevance: It must relate to the user’s needs.

·         Timeliness: It should be available at the right time.

·         Completeness: It should provide all the necessary details.

·         Clarity: It should be easy to understand and not confusing.

·         Reliability/Trustworthy: Should come from a trusted source.

·         Adequacy/Concise: Should have just enough detail (not too much, not too little).

3. Difference between Data and Information

Feature	Data	Information
Meaning	Raw facts	Processed facts (meaningful)
Form	Unorganized (numbers, text, symbols)	Organized and structured
Usefulness	Not directly useful	Useful for decision-making
Example	1001, 1002, 1003	“Student IDs of class members are 1001, 1002, 1003”