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COMPUTER SYSTEM MAINTENANCE  

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LEARNING OUTCOME 2

Determining Your Computer System Model

There are several ways to check your computer's system model, depending on your operating system and preferred method:

For all Windows versions:

  1. System Information:
    • This is the easiest and most reliable method.
    • Press the Windows Key + S to open the search bar.
    • Type "System Information" and select the app from the results.
    • Look for the "System Model" entry in the right pane. This will display the manufacturer and model name of your computer.
  2. Command Prompt:
    • Open the Command Prompt by searching for it in the Start menu or pressing Windows Key + R, typing "cmd", and pressing Enter.
    • Type the following command and press Enter: wmic csproduct get name
    • This command will display the model name of your computer.

Windows PowerShell (Windows 10/11):

These methods provide reliable ways to determine your computer's system model on Windows operating systems.

Command Prompt Codes

  1. Date and Time:
    • date: Shows the current system date (e.g., Fri 04-26-2024).
    • time: Shows the current system time (e.g., 16:22:13.48).
  2. Navigating Directories:
    • cd <directory name>: Changes the current directory to the specified directory. For example, cd Documents navigates to the Documents folder within your user directory.
    • cd ..: Moves up one level in the directory structure. For example, if you're currently in the Documents folder, cd .. takes you back to your user directory.
    • cd\: Changes the current directory to the root directory of the drive. For example, cd\ takes you to the root of the C drive.
  3. Finding Files:
    • dir: Lists the contents of the current directory.
    • dir/w: Lists the contents of the current directory in a wider format, showing full paths.
    • dir/s: Lists the contents of the current directory and all subdirectories recursively.
    • dir/b: Lists only the filenames without any additional information.
    • dir/p: Lists the directory contents one page at a time.

    Example: To find all files with the extension ".txt" in the C drive and its subdirectories, use: dir C:\*.txt /s

  4. Going Back in Directory History:
    • cd -: Navigates back to the previous directory you were in. This allows you to easily retrace your steps within the command prompt.
  5. Important Additional Codes:
    • copy <source> <destination>: Copies a file from the source location to the destination. For example, copy example.txt C:\Backup copies the file "example.txt" to the "Backup" folder on the C drive.
    • move <source> <destination>: Moves a file from the source location to the destination, removing it from the original location. For example, move example.txt C:\Backup moves the file "example.txt" to the "Backup" folder on the C drive, deleting it from its original location.
    • ren <old_name> <new_name>: Renames a file. For example, ren old_file.txt new_file.txt renames "old_file.txt" to "new_file.txt".
    • del <filename>: Deletes a file. Use with caution! For example, del junk.txt deletes the file "junk.txt" from the current directory. To delete a file with specific confirmation, use del /f <filename>.
    • format <drive letter>: Formats a disk drive. WARNING! This erases all data on the drive. Use with extreme caution!
  6. Creating a Directory:
    • mkdir <directory name>: Creates a new directory with the specified name. For example, mkdir NewFolder creates a new folder called "NewFolder" in the current directory.
  7. Deleting a Directory:
    • rmdir <directory name>: Removes an empty directory. WARNING! Use with caution, as it cannot delete non-empty directories. To delete a directory and its contents, use the following command (be cautious!): rmdir /s /q <directory name>
    • This command recursively deletes the specified directory and all its contents. The /s switch forces the deletion of subdirectories, and the /q switch suppresses confirmation prompts.

These command prompt codes are essential for navigating and managing files and directories in a Windows environment.

Five Basic Types of Computer Operations

  1. Input

    Imagine a user typing on a keyboard. The keyboard acts as an input device, converting the physical key presses into electrical signals. These signals travel through a cable to the computer.

        +---------+       +----------+
    | Keyboard |----> | Computer |
    +---------+       +----------+
  2. Processing

    Inside the computer, the Central Processing Unit (CPU), which acts like the brain, receives the electrical signals from the keyboard. The Control Unit (CU) within the CPU decodes the signals and identifies them as key presses. The Arithmetic Logic Unit (ALU) then processes this information according to the program instructions stored in memory.

  3. Output

    Based on the processed data, the computer might need to display something on the screen. The CPU sends signals to the video card, which translates the data into visual information the monitor can understand. The monitor then displays the information, such as the typed letter, on the screen.

  4. Storage

    Not all information needs to be displayed immediately. The computer might need to store some data for later use. The hard disk drive (HDD) or solid-state drive (SSD) acts as a secondary storage device, providing long-term storage for programs and data.

  5. Control

    These operations all need to be coordinated. The motherboard acts as the central circuit board, providing communication pathways for all components within the computer. It ensures that data flows smoothly between the CPU, memory, storage devices, and other components.

These five basic types of computer operations work together to enable the functionality of modern computing systems.

Data Processing Cycle

The data processing cycle is the fundamental concept behind how computers transform raw data into meaningful information. It's a continuous loop that ensures data is received, manipulated, stored, and presented in a way that serves the user's needs. Here's a breakdown of the four key stages:

  1. Input:
    • This is the starting point where data enters the computer system.
    • Various input devices like keyboards, mice, scanners, microphones, and webcams act as bridges between the user and the computer.
    • These devices convert user actions (e.g., key presses, mouse clicks, scanned documents, recorded voice) into electrical signals that the computer can understand.
  2. Processing:
    • This stage is the heart of the data processing cycle, where the raw data is manipulated and transformed according to a program's instructions.
    • The Central Processing Unit (CPU), also known as the brain of the computer, plays a crucial role in processing. It has two main components:
      • Control Unit (CU): Decodes program instructions, fetches data from memory, and directs other components on how to process it.
      • Arithmetic Logic Unit (ALU): Performs calculations and logical operations on the data based on the instructions.
    • Memory (RAM): Holds the data and program instructions currently being used by the CPU for quick access.
  3. Output:
    • This stage involves presenting the processed information or results generated by the computer system to the user.
    • Output devices like monitors, printers, speakers, and projectors are responsible for displaying the data in a human-readable or perceivable form.
    • For instance, after a user types a document, the processed data is displayed on the screen (monitor) as text.
  4. Storage:
    • Not all data needs to be displayed immediately or used actively. Secondary storage devices like hard disk drives (HDDs), solid-state drives (SSDs), USB drives, and external storage devices provide long-term storage for programs and data.
    • This stage ensures information is saved and available for future use or retrieval.

The data processing cycle is a continuous loop that ensures data is efficiently transformed into meaningful information for the user.

Interconnection Structures

Here are two common interconnection structures for a computer system with processors, memory, and I/O modules:

  1. Bus-Based Interconnection Structure:

    This is the simpler and more traditional approach. A single bus acts as a shared communication pathway for all components.

    • Components:
      • Processors (CPU)
      • Memory modules
      • I/O modules (controllers for peripherals like printers, disks, etc.)
      • Bus (data pathway)
      • Bus controller (manages access to the bus)
    • Operation:
      • Processors and I/O modules initiate data transfer requests.
      • The bus controller arbitrates access to the bus to avoid conflicts.
      • The requesting component puts the data and address information on the bus.
      • The intended recipient (memory or another device) listens for its address and retrieves the data.
    • Advantages:
      • Simple and cost-effective design
      • Easy to understand and implement
      • Suitable for smaller systems with moderate communication needs
    • Disadvantages:
      • Bottleneck: The bus becomes a bottleneck as system performance increases and more components compete for access.
      • Limited scalability: Adding more processors or memory modules can significantly impact performance.
  2. Point-to-Point Interconnection Structure:

    This approach uses dedicated connections between components, offering higher performance and scalability.

    • Components:
      • Processors (CPU)
      • Memory modules
      • I/O modules (controllers for peripherals)
      • Point-to-point connections (dedicated communication pathways)
    • Operation:
      • Processors and I/O modules communicate directly with each other or with memory modules through dedicated connections.
      • No central bus controller is needed, reducing latency.
      • Data packets are sent containing addresses, control information, and the actual data.
    • Advantages:
      • Higher bandwidth and lower latency: Dedicated connections facilitate faster data transfer between components.
      • Scalability: The system can be easily expanded by adding more processors, memory, or I/O modules without significantly impacting performance.
    • Disadvantages:
      • Increased complexity: Designing and managing a complex network of point-to-point connections requires more effort.
      • Higher cost: Implementing dedicated connections for all components can be more expensive.

Both bus-based and point-to-point interconnection structures have their advantages and disadvantages, making them suitable for different types of computer systems.

Bus Structure

A bus structure is a communication pathway within a computer system that allows various components like processors, memory, and I/O devices to exchange data. Let's break down the key elements:

  1. Data Lines:
    • These are a group of electrical wires that carry the actual data being transferred between components.
    • The width of the data lines (number of wires) determines how many bits can be transmitted simultaneously. Wider data lines allow for faster data transfer.
    • Typical data bus widths range from 8 bits (8 wires) to 64 bits (64 wires) or even wider in high-performance systems.
  2. Address Lines:
    • These lines specify the source or destination of the data being transferred on the data lines.
    • The number of address lines determines the maximum number of memory locations or I/O devices that can be addressed by the system.
    • A wider address bus allows for addressing a larger memory space and supporting more connected devices.
  3. Control Lines:
    • These lines carry control signals that regulate the flow of data on the bus.
    • They manage tasks like:
      • Read/Write operations: Specify whether data is being sent to memory (write) or retrieved from memory (read).
      • Synchronization: Ensure different components are in sync during data transfer to avoid collisions.
      • Error detection: Help identify errors that may occur during data transmission.
  4. Bus Interface Unit (BIU):
    • This is a component within each device connected to the bus that acts as an interface between the device and the bus itself.
    • The BIU translates data and control signals between the device's internal format and the format used on the bus.
    • It also coordinates data transfer requests from the device to the bus controller.
  5. Bus Controller:
    • This optional component manages access to the bus and arbitrates conflicts when multiple devices attempt to use it simultaneously.
    • In a simple bus system, there might be a central bus controller.
    • In more complex systems, a distributed arbitration scheme might be used, where devices negotiate access rights among themselves.

The bus structure is a critical component of computer systems, enabling efficient communication between various hardware components.

Hardware Details Transparent to the Programmer

  1. Control Signals:
    • Programmers typically don't need to directly manipulate control signals. These are low-level electrical signals within the CPU that govern various operations like fetching instructions from memory, decoding them, and controlling data flow between components.
    • The hardware automatically generates these signals based on the program instructions being executed.
  2. Interfaces between the Computer and Peripherals:
    • Programmers interact with peripherals through device drivers. These drivers act as translators, converting high-level programming language commands into specific instructions understood by the peripheral's controller.
    • For instance, a printer driver translates a "print" command into a sequence of commands for the printer controller to move the print head, fire ink cartridges, and control paper movement.
  3. Memory Technology Used:
    • The specific type of memory technology (e.g., DRAM, SRAM) is usually transparent to the programmer. However, they might be aware of different memory levels (cache, main memory, secondary storage) and their access speeds.
    • Programmers can optimize their code by considering the access times of different memory levels. For example, frequently used data might be stored in the faster cache for quicker access.

These hardware details are abstracted away from programmers, allowing them to focus on writing efficient and functional code without worrying about low-level hardware operations.

Model of a Simplified Computer Architecture

Here's a simplified model to illustrate some core components:

This simplified model highlights the core components of a computer architecture and their primary functions.

Interaction with Peripherals

This interaction ensures seamless communication between the computer and its peripherals.

Memory Access

Memory access is managed efficiently by the CPU and MMU, abstracting physical memory details from programmers.

Benefits of Hardware Transparency

Hardware transparency simplifies programming and enhances the portability of software across different systems.

Data Representation

Data representation refers to the various ways computers store and manipulate information. Numbers are a fundamental type of data, and computers use different number systems to represent them. Here's a breakdown of the four common number systems:

  1. Decimal Number System (Base-10):
    • This is the most common number system used in everyday life.
    • It uses ten digits (0-9) to represent numbers.
    • The value of each digit depends on its position within the number.
    • Example: In the number 321, the digit "3" represents three hundreds (3 x 10^2), "2" represents two tens (2 x 10^1), and "1" represents one unit (1 x 10^0).
  2. Binary Number System (Base-2):
    • This is the fundamental number system used by computers.
    • It uses only two digits (0 and 1) to represent numbers.
    • Each digit represents a power of 2. The rightmost digit is the 2^0 (one's) place, the next digit is the 2^1 (two's) place, and so on.
    • Example: The binary number 1011 represents one eight (1 x 2^3), zero fours (0 x 2^2), one two (1 x 2^1), and one unit (1 x 2^0).
  3. Octal Number System (Base-8):
    • This system uses eight digits (0-7) to represent numbers.
    • It is less common than binary but can be a convenient way to represent large binary numbers in a more compact form.
    • Each digit represents a power of 8. The rightmost digit is the 8^0 place, the next digit is the 8^1 place, and so on.
    • Example: Octal numbers are often used in computer permissions settings.
  4. Hexadecimal Number System (Base-16):
    • This system uses 16 digits (0-9 and A-F) to represent numbers.
    • It is another way to represent large binary numbers more concisely than binary itself.
    • Each digit represents a power of 16. The rightmost digit is the 16^0 place, the next digit is the 16^1 place, and so on.
    • Example: Hexadecimal numbers are commonly used in computer memory addresses and machine code.

These number systems are fundamental to how computers represent and manipulate data.

Summary Table of Number Systems

This table summarizes the key characteristics of the four common number systems used in computing.

Number System Base Digits Example
Decimal 10 0-9 321
Binary 2 0, 1 1011
Octal 8 0-7 143
Hexadecimal 16 0-9, A-F B7F

Conversions Between Decimal, Binary, Octal, and Hexadecimal Number Systems

Decimal to Binary Conversion

There are two common methods to convert a decimal number to binary:

Method 1: Repeated Division by 2

  1. Divide the decimal number by 2.
  2. Write down the remainder (0 or 1) as the rightmost digit of the binary equivalent.
  3. Continue dividing the quotient (the result of the previous division) by 2, ignoring any decimal remainder.
  4. Write down the remainder (0 or 1) for each division as the next digit to the left in the binary equivalent.
  5. Repeat steps 3 and 4 until the quotient becomes 0.
  6. The binary equivalent is the sequence of remainders read from bottom (rightmost) to top (leftmost).

Example: Convert decimal 23 to binary.

  1. 23 / 2 = 11 (remainder 1)
  2. 11 / 2 = 5 (remainder 1)
  3. 5 / 2 = 2 (remainder 1)
  4. 2 / 2 = 1 (remainder 0)
  5. 1 / 2 = 0 (remainder 1)

Reading the remainders from bottom to top: 10111 (binary equivalent of 23).

Method 2: Using Powers of 2

  1. Find the highest power of 2 that is less than or equal to the decimal number.
  2. If that power of 2 can be subtracted from the decimal number without going negative, write down a 1 in the binary equivalent and subtract that power of 2 from the number.
  3. Repeat step 2 with the remaining number and progressively lower powers of 2 until you reach 1.
  4. Write down 0s for any powers of 2 that weren't used in the subtraction process.
  5. The binary equivalent is the combination of 1s and 0s obtained.

Example: Convert decimal 23 to binary (using powers of 2).

  1. The highest power of 2 less than or equal to 23 is 2^4 (16).
  2. 23 - 16 = 7. Since 7 is greater than 0, we write down 1 and subtract 16.
  3. 7 - 2^3 (8) = -1. Since subtracting 8 would result in a negative number, we skip 2^3 and move to the next power of 2.
  4. 7 - 2^2 (4) = 3. We write down 1 and subtract 4.
  5. 3 - 2^1 (2) = 1. We write down 1 and subtract 2.
  6. 1 - 2^0 (1) = 0. We write down 1.

Combining the 1s and 0s: 10111 (binary equivalent of 23).

Decimal to Octal Conversion

  1. Divide the decimal number by 8 (octal is base-8).
  2. Write down the remainder (0-7) as the rightmost digit of the octal equivalent.
  3. Continue dividing the quotient by 8, ignoring any decimal remainder.
  4. Write down the remainder for each division as the next digit to the left in the octal equivalent.
  5. Repeat steps 3 and 4 until the quotient becomes 0.
  6. The octal equivalent is the sequence of remainders read from bottom to top.

Example: Convert decimal 23 to octal.

  1. 23 / 8 = 2 (remainder 7)
  2. 2 / 8 = 0 (remainder 2)

Reading the remainders from bottom to top: 27 (octal equivalent of 23).

Decimal to Hexadecimal Conversion

  1. Divide the decimal number by 16 (hexadecimal is base-16).
  2. Write down the remainder (0-9 or A-F) as the rightmost digit of the hexadecimal equivalent. A represents 10, B represents 11, and so on until F represents 15.
  3. Continue dividing the quotient by 16, ignoring any decimal remainder.
  4. Write down the remainder for each division as the next digit to the left in the hexadecimal equivalent.
  5. Repeat steps 3 and 4 until the quotient becomes 0.
  6. The hexadecimal equivalent is the sequence of remainders read from bottom to top.

Example: Convert decimal 23 to hexadecimal.

  1. 23 / 16 = 1 (remainder 7)
  2. 1 / 16 = 0 (remainder 1)

Reading the remainders from bottom to top: 17 (hexadecimal equivalent of 23).

Conversions in Reverse (Other Systems to Decimal)

Binary to Decimal Conversion

  1. Each digit in the binary number represents a power of 2.
  2. Multiply each digit by its corresponding power of 2 (starting from the rightmost digit with 2^0 and moving left with increasing powers of 2).
  3. Add the products of all digits together.

Example: Convert binary 11011 to decimal.

  1. 1 (rightmost digit) * 2^0 = 1
  2. 0 * 2^1 = 0
  3. 1 * 2^2 = 4
  4. 0 * 2^3 = 0
  5. 1 (leftmost digit) * 2^4 = 16

Add all the products: 1 + 0 + 4 + 0 + 16 = 21 (decimal equivalent of 11011).

Octal to Decimal Conversion

  1. Each digit in the octal number represents a power of 8.
  2. Multiply each digit by its corresponding power of 8 (starting from the rightmost digit with 8^0 and moving left with increasing powers of 8).
  3. Add the products of all digits together.

Example: Convert octal 27 to decimal.

  1. 7 (rightmost digit) * 8^0 = 7
  2. 2 (leftmost digit) * 8^1 = 16

Add the products: 7 + 16 = 23 (decimal equivalent of 27).

Hexadecimal to Decimal Conversion

  1. Each digit in the hexadecimal number represents a value based on its position. Digits 0-9 represent their corresponding decimal values, and A represents 10, B represents 11, and so on until F represents 15.
  2. Multiply each digit by its corresponding value based on its position (starting from the rightmost digit with 16^0 and moving left with increasing powers of 16).
  3. Add the products of all digits together.

Example: Convert hexadecimal 17 to decimal.

  1. 7 (rightmost digit) * 16^0 = 7
  2. 1 (leftmost digit) * 16^1 = 16

Add the products: 7 + 16 = 23 (decimal equivalent of 17).

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