1.1- input, output, and storage

Input, Output, and Storage Devices

  • Input Devices

    • Supply the CPU with data.

    • Allow users to instruct the computer.

    • Examples: keyboard, mouse, touchscreen.

  • Output Devices

    • Provide data/information to the user.

    • Examples: monitors, printers, headphones.

  • Input/Output Devices

    • Devices that can both input and output data.

    • Examples: touchscreen, game controller (with vibration), headphones (mic + speakers), keypad (with screen), calculators.

Primary Memory

  • General Memory Function

    • Memory is where binary data is stored in a computer.

  • RAM (Random Access Memory)

    • Also known as main memory.

    • Stores programs currently in use.

    • Enables multi-tasking by allowing multiple programs to run simultaneously.

    • Works by copying necessary data to RAM for quick CPU access.

    • Stores instructions and data needed for processing by the CPU.

    • Volatile memory: loses data when power is off.

    • Data is loaded from hard disk to RAM for faster access.

  • ROM (Read Only Memory)

    • Non-volatile memory; retains data without power.

    • Stores essential boot sequence instructions for starting the computer and loading the OS.

    • Data on ROM cannot be easily overwritten by users.

  • Virtual Memory

    • Allows for multitasking when RAM is full by relocating less-used programs to the hard disk.

    • Virtual memory uses hard disk space, which is slower than RAM, but helps maintain system speed when multitasking.

Secondary Storage

  • Magnetic Storage

    • Data is stored through patterns of magnetization.

    • Examples: hard disks, magnetic tapes.

    • Represents binary as magnetized (1) and demagnetized (0) points.

  • Optical Storage

    • Uses laser technology; data is recorded as pits (1) and lands (0) on a shiny surface.

    • Examples: CDs, DVDs, Blu-rays.

  • Solid State Storage

    • Stores data by trapping electrons in position, using electric currents.

    • Includes USB drives, SSDs, and SD cards.

Comparison of Storage Types

  • Capacity

    • Magnetic (largest), Solid-state (middle), Optical (smallest: CD ~ 700MB, DVD 4.3GB, Blu-ray 50GB).

  • Speed of Access

    • Solid-state (fastest: 600MB/s+), Magnetic (middle: 300MB/s), Optical (slowest: 10-36MB).

  • Portability

    • Optical (good, light, requires reader), Solid-state (good), Magnetic (bad).

  • Durability

    • Solid-state (good), Optical (can scratch but tough), Magnetic (bad: mechanical issues).

  • Reliability

    • Magnetic (best, long-lasting), Optical (okay), Solid-state (good but limited read/write).

  • Cost per GB

    • Magnetic (best: 2p/GB), Optical (okay), Solid-state (worst: 5p/GB).

Boot Process

  • The BIOS performs a Power-On Self-Test (POST) immediately after startup.

    • It identifies, configures, tests, and connects to the OS.

    • These steps collectively are referred to as the boot process.