Overview of Computer System

CLASS: SSS One

Definition of Computer System

A computer system is an electronic device that works with data following a set of instructions. It can:

• Manipulate data and produce output using step-by-step instructions.
• Receive, store, retrieve, process, and output data.
• Solve problems by accepting data, performing operations, and presenting results under the direction of detailed instructions.

Constituents of a Computer

A computer system is primarily made up of two main components:

• Hardware
• Software

Hardware

Hardware refers to all the physical parts of a computer system that you can see, touch, or handle. These are the tangible components that make up the computer.

Examples of Hardware

The following list represents a basic set of hardware found in most computers:

1. PC case (or system unit casing)
2. Motherboard
3. Hard Disk Drive (HDD) or Solid State Drive (SSD)
4. Floppy Disk Drive (FDD)
5. Compact Disc Drive (CDD)
6. Digital Versatile Disc Drive (DVD)
7. Monitor
8. Keyboard
9. Power supply unit
10. Mouse
11. Cables and wires

Classification of Hardware

Hardware components can be classified based on their functions within the computer system:

1. Input Unit: This unit helps users enter data and instructions into the computer.
   Examples: Keyboard, Mouse, Light pen, Joystick, Scanner, Microphone.
2. Output Unit: The output unit displays or communicates the results of data processing from the computer to the user.
   Examples: Monitor, Projector, Printer, Speakers.
3. Memory Unit: The memory unit stores data and instructions for the computer to use.
   Examples: RAM (Random Access Memory), ROM (Read-Only Memory), Flash drive, Hard disk.
4. Processing Unit: The processing unit carries out or executes the instructions of a computer program. It's the "brain" of the computer.
   Example: CPU (Central Processing Unit).

Important Terms Related to Hardware

• System Unit: This is the main enclosure of a desktop computer that houses its electronic components, including the motherboard, CPU, memory, and storage drives.
• Peripherals: A computer peripheral is any external device that provides input or receives output from the computer. It refers to all hardware devices that are attached to the computer system and are controlled by it. Peripheral devices are sometimes also called "I/O devices."

Software

Software is a set of instructions and procedures given to the computer to perform specific activities or tasks. Unlike hardware, software is intangible—it cannot be seen or touched directly. It's the "brain" of the computer, telling the hardware what to do.

Examples of Software

Here are some common examples of software found in most computers:

1. Operating Systems (e.g., Windows, macOS, Linux)
2. Word Processors (e.g., MS Word, Google Docs)
3. Antivirus Software (e.g., Norton Anti-virus, Avast)
4. Graphic Design Software (e.g., CorelDraw, Adobe Photoshop)
5. Database Management Systems (e.g., MS Access, Oracle)
6. Spreadsheet Software (e.g., MS Excel, Google Sheets)
7. Programming Languages (e.g., BASIC, Python, C++)
8. Assemblers and Compilers (for translating code)

Types of Software

Computer software is generally divided into two broad categories:

1. System Software
2. Application Software

System Software

System software is a collection of programs designed to control and manage the computer hardware and other software resources. It creates a platform for application software to run.

Examples of System Software

• Operating System (e.g., Windows, macOS, Android)
• Translators (e.g., Compilers, Interpreters, Assemblers)
• Utility Programs (e.g., Antivirus software, Disk cleaners, File compressors)

Application Software

Application software consists of programs that enable users to perform specific tasks or activities that are not related to the core operation of the computer itself. These are the programs you use to do work, play, or communicate.

Examples of Application Software

• Word processing software (for writing documents)
• Spreadsheet software (for calculations and data organization)
• Presentation software (for creating slideshows)
• Database packages (for managing large amounts of information)
• Graphics packages (for creating and editing images)
• Gaming Software (for entertainment)
• Web Browsers (e.g., Chrome, Firefox)

Characteristics of the Computer

Computers possess several remarkable characteristics that make them incredibly useful:

1. Speed: Computers can perform calculations and tasks at incredibly high speeds, far exceeding human capabilities. Their speed is measured in Hertz (Hz), where a 4 GigaHertz (4 GHz) CPU can perform 4 billion operations per second.
2. Accuracy: Computers are highly accurate and perform operations without errors, as long as they are given correct instructions and data. They can run for long periods without making mistakes.
3. Storage: Computers have a vast capacity to store large amounts of data in a small physical space, leading to significant savings in physical storage area compared to traditional methods.
4. Versatility: A single computer can perform a wide variety of tasks. You can use it for arithmetic calculations, word processing, sending emails, Browse the internet, playing games, and much more.
5. Automation: Once a computer is given a set of instructions (a program), it can execute the entire task automatically without further human intervention until the job is completed.
6. Diligence: Unlike humans, computers do not get tired, bored, or lose concentration. They can perform repetitive tasks continuously for days or weeks without any loss of speed, accuracy, or efficiency.
7. Cost-effectiveness: While initial costs can vary, hardware costs have generally been decreasing over time, and computers can significantly reduce operational costs for businesses and individuals by automating tasks.
8. Electronic in Nature: Computers are built from electronic components like transistors, integrated circuits (ICs), microprocessors, capacitors, and resistors, which require electricity to function.
9. Interactive: Computers provide a user interface that allows users to interact with them by inputting data and commands, and receiving feedback or results.

Limitations of a Computer

Despite their many advantages, computers also have certain limitations:

1. No Intelligence (IQ=0): Computers cannot do anything unless they are explicitly programmed to perform a specific task. They lack their own intelligence or common sense.
2. Cannot Interpret Data on Their Own: Computers process data but cannot inherently understand or interpret the meaning of the data they generate without human input or programmed logic.
3. Cannot Detect Input Errors: A computer cannot determine if the data an operator feeds into it is incorrect or illogical; it will process whatever it receives.
4. Cannot Implement Decisions: While computers can suggest solutions or make complex calculations, they cannot implement decisions in the real world without human or robotic intervention.
5. Health Issues from Prolonged Use: Excessive or improper use of computers can lead to health problems like eye strain, fatigue, repetitive strain injuries (RSI), and poor posture.
6. Over-dependence and Downtime: Over-reliance on computers means that work can be halted or severely impacted during system breakdowns, power outages, or cyber-attacks (like virus infections).
7. Security Vulnerabilities: Computers can be hacked, leading to data theft, privacy breaches, or system damage if not properly secured.

Classification of Computers

Classification According to Purpose

1. General Purpose Computer: These computers are designed to perform a wide variety of tasks. They are flexible and can be used for many different applications by changing the software. Examples include personal computers (desktops, laptops).
2. Specific Purpose Computer: These computers are designed to handle a single, dedicated problem or a very limited set of tasks. They are optimized for that specific function. Examples include computers in washing machines, calculators, or traffic light systems.

Classification According to Type of Data-handling Techniques

1. Analog Computers: These computers represent data by measurable physical quantities, such as voltages, pressures, or the rotation of gears, to solve problems. They are often used for continuous data measurements.
2. Digital Computer: A digital computer performs calculations and logical operations using quantities represented as discrete digits, usually in the binary number system (0s and 1s). Most modern computers are digital.
3. Hybrid Computer: A hybrid computer combines the functionalities of both a digital and an analog computer. It uses analog components for specific tasks where continuous measurement is beneficial and digital components for control and general-purpose processing.

Classification of Computer by Size/Speed

1. Microcomputer: These are relatively small, low-cost computers designed for individual users. They typically consist of a CPU (microprocessor), input unit, output unit, storage unit, and software. Examples include personal computers, laptops, and tablets.
2. Minicomputers: Digital computers generally used in multi-user systems. They have higher processing speed and storage capacity than microcomputers and can support anywhere from 4 to 200 users simultaneously. They were popular in businesses and research institutions.
3. Mainframe Computers: These are multi-user, multi-programming, and high-performance computers. They operate at very high speeds, have massive storage capacities, and can handle the workload of hundreds or thousands of users concurrently. Large organizations like banks and government agencies use them.
4. Supercomputer: Supercomputers are the fastest and most expensive machines, designed to perform complex calculations at extreme speeds. Their speed is typically measured in FLOPS (Floating Point Operations Per Second), and some can perform trillions of calculations per second. They are used for advanced scientific and engineering problems.

Block Diagram of the Computer System

Understanding the basic block diagram helps visualize how different parts of a computer system work together.