Chapter: Computer Fundamentals Notes

Secondary Storage Devices

  • Secondary storage devices store data for long-term retention and hold data permanently until needed; data is loaded into main memory when required.
  • Primary memory (RAM) vs secondary storage: RAM is volatile; secondary storage maintains data without power.
  • Types of secondary storage discussed:
    • Disk drive
    • Magnetic encoding of data on a spinning circular disk.
    • Data is stored on a magnetically encoded spinning disk; access involves reading/writing to the disk as it rotates.
    • SSD (Solid State Drive)
    • Faster than disk drives; no moving parts; data stored in solid-state memory.
    • Typically more expensive than hard disks.
    • Flash memory
    • Portable and does not rely on a physical disk.
    • Examples include USB drives, memory cards used in cameras and mobile devices; highly portable and durable.
  • Notes on examples of flash memory:
    • USB flash drives, memory cards for cameras and mobile devices; portable devices with no moving parts.
  • Encoding and access concept:
    • Data is encoded into a readable form, then converted to a form suitable for storage (unreadable during storage, readable on access).
  • Summary: secondary storage provides non-volatile, long-term data retention and load-time access to programs and data when needed.

Input, Output, and Peripheral Devices

  • Input devices: collect data from users or other devices and pass it to the processor.
    • Examples: keyboard, mouse, touchscreen, scanner, cameras.
    • Other data sources: Bluetooth/wireless input, voice data.
    • Disk drives can be considered input devices because they load programs into main memory.
    • Data flow: user or device provides data -> input device -> processor via RAM.
  • Output devices: receive data from the computer and present it (display, projection, physical reproduction).
    • Computer can operate without an output device, but you cannot observe what it’s doing without one.
    • Output formats: hard copy (printed on paper) vs soft copy (on screen/monitor).
    • Disk drives and USB drives can be considered as output devices in the sense that data is written to them (saved) after processing.
    • Examples: video displays, printers.
  • Basic function of input/output in data presentation:
    • Hard copy vs soft copy distinction: soft copy is display on screen; hard copy is printed on paper.
    • Output devices help demonstrate results and provide a tangible record of results.
  • The disk drives/USB drives role as storage devices: act as storage for data, which can be read (input) or written (output).

The Computer’s Basic Function Diagram

  • Core components involved: Input devices, Memory (RAM), Central Processing Unit (CPU), Control Unit, and Output devices.
  • Data path and storage flow:
    • Input devices provide data to the computer; inputs and intermediate results are stored in memory.
    • CPU processes data based on user instructions.
    • Control Unit manages operations of computer components.
    • Output devices display results to the user.
  • Disk drives/SSD as data sources for programs: program instructions stored on disk/SSD are loaded into main memory when executed.

Examples of Input-Process-Output

  • Example 1: Calculator use
    • Input: numbers 1 to 9 from keyboard.
    • Processing: calculator computes results in a fraction of a second.
    • Output: result displayed on screen.
  • Example 2: Video calling
    • Inputs: audio data (microphone) and video data (webcam).
    • Processing: CPU handles data, packets are prepared for transmission over the Internet.
    • Outputs: audio played through speaker; video displayed on monitor.
  • Diagrammatic flow: inputs (audio/video) -> CPU -> data packets -> Internet -> recipient’s device; outputs (audio/video) on receiving end.

Short Activity Prompts (Note for Students)

  • Activity 1: Which peripheral is the most recent invention? Obtain details of its functionality and cost.
  • Activity 2: Explain or draw the architecture diagram as shown (the computer’s architecture).
  • Activity 3: Identify the processor that is the heart of your computer, its speed, and research the history and today’s most popular chips, including basic characteristics.
  • Submission method: GitHub server will be used for submitting activities; a link will be provided.
  • Deadlines for first assessment: 27 October to 9 November (dates may indicate window).

Software and Data Handling

  • Software is divided into two major categories:
    • Application software: programs that make the computer useful for everyday tasks (e.g., Gmail, games, web browsers).
    • System software: controls and manages the computer’s operations (e.g., operating systems, utility software).
  • Utility software: enhances computer operations and safeguards data (e.g., antivirus software).
  • Software development tools: used to create, modify, and test software; categorized as system software.
  • The distinction: Application software vs System software; the latter controls hardware operations.

Data Representation: Bits, Bytes, and Character Encoding

  • Computers do not understand human-readable text directly; they understand binary numbers (zeros and ones).
  • Key data units:
    • Bit: the smallest unit of digital information; holds a value of 0 or 1.
    • Byte: a collection of 8 bits; storage unit for characters and small numbers; 1 byte = 8 bits.
    • Common statement from the lecture: 1 byte = 8 bits.
  • Binary number representation: bits are weighted by powers of two.
    • If a binary number has bits b0, b1, …, b{n-1}, its value is: $$ ext{Value} = igsqcup{i=0}^{n-1} bi \, 2^i = b0 2^0 + b_1 2^1 + \