Comprehensive Computer Fundamentals Notes

What Is a Computer?

  • Electronic device for processing data.
    • Accepts input, stores data, processes it and delivers output based on user requirements.

Advantages

  • Works efficiently and quickly.
  • Useful in virtually every field.
  • Provides millions of pieces of information in seconds.
  • Facilitates reliable data storage and retrieval.
  • High accuracy even with large volumes of data.
  • Performs repetitive tasks without fatigue.
  • Acts as a dedicated “data-processor.”
    • Gather → Merge → Sort → Print.

Characteristics of Computers

  • Speed
    • Performs mathematical calculations in μs\mu s (microseconds) or nsns (nanoseconds).
  • Accuracy: 100%100\% precise if input and program are correct.
  • Diligence: Can execute millions of operations without loss of concentration or fatigue.
  • Versatility: Capable of handling diverse tasks concurrently.
  • Reliability: Consistently supplies complete, correct information.
  • Memory
    • Long-term, high-capacity storage.
  • Automation: Executes instructions automatically once programmed.
  • Consistency & Storage Capacity: Delivers identical results; can store huge data volumes.
  • Resilience Power (failure recovery) and other minor traits.

History of Computing

  • Ancient Tools & Abacus (≈3000 BCE – 100 BCE): manual arithmetic aids.
  • Mechanical Calculators (17th–19th C): automated arithmetic devices.
  • Analytical Engine (1833–1843)
    • Designed by Charles Babbage; used punched cards for programs → conceptual “first computer.”
  • Punched-Card Systems (late-19th – early-20th C): data/program encoding.
  • First Electronic Computers (1930s–1940s)
    • Konrad Zuse Z3 (1941): electromechanical programmable.
    • Colossus (1944): first digital electronic code-breaking machine.
    • ENIAC (1945): general-purpose electronic digital; vacuum tubes for processing.
  • Stored-Program Concept (late 1940s–1950s): data & instructions share same memory.
  • Transistors & Integrated Circuits (1950s–1960s)
    • Jack Kilby, Robert Noyce; smaller, faster, energy-efficient.
  • Microprocessors & Miniaturization (1960s–1970s)
    • Intel → rise of personal computers.
  • Personal-Computer Revolution (1970s–1980s)
    • Apple, IBM popularize PCs.
  • Mobile Internet & WWW (1990s) – Tim Berners-Lee.
  • Mobile Computing & Smartphones (21st C).
  • Cloud Computing & AI (2000s–present).

Computer Generations

  • 1st (1940s–1950s): Vacuum tubes, magnetic drums/tapes, machine & assembly language; large, hot, power-hungry; examples: ENIAC, UNIVAC 1.
  • 2nd (1950s–1960s): Transistors; magnetic core memory; assembly + early high-level (FORTRAN, COBOL); IBM 1401, UNIVAC 1107.
  • 3rd (1960s–1970s): Integrated Circuits (ICs); RAM/ROM; high-level languages (BASIC, Pascal, C); IBM 360.
  • 4th (1970s–present): VLSI microprocessors; desktops, laptops; languages: Java, C#, Python; Apple II, IBM PC.
  • 5th (present & future): AI, ULSI, parallel processing, natural-language interface; smartphones, tablets.

Classification by Size/Power

Microcomputers

  • One microprocessor (CPU) + I/O + memory on micro-chips.
  • Word length up to 16 bits.
  • Limited storage; inexpensive, portable, low-power; slower than larger systems.

Minicomputers

  • Mid-size between micro & mainframe; more powerful; serve multiple users (≈20 terminals).
  • Word sizes 16, 24, 32 bits; storage ≈2 MB words.
  • Inexpensive relative to mainframes; but higher maintenance and power requirements.

Mainframes

  • 32-bit+ processors, huge storage, high speed, can manage WAN nodes.
  • Examples: DEC, ICL, IBM 3000 series.

Workstations

  • High-performance single-user systems; used for CAD/CAM, DTP, software dev.
  • Large graphics memory (≈64 MB); stand-alone; OSs: UNIX, Windows NT.

Supercomputers

  • Extremely costly; execute few programs at incredible speeds via massive parallelism.
  • 8–64 MB (historical) primary memory; used for scientific simulations, animated graphics.

Network Computers / Thin Clients

  • Diskless desktops relying on servers; cheaper and easier to manage than full PCs.

Laptops

  • Battery-powered portable computers; same functions as desktops; integral display, keyboard, pointing stick/trackpad; energy-efficient.

Fundamental Operations

  • Input → Processing → Output → Storage → Communication.
    • Input devices (keyboard, mouse) feed data.
    • CPU manipulates data via algorithms.
    • Output devices present results (text, graphics).
    • Storage retains information (HDD/SSD).
    • Communication exchanges data between systems.

Core Components

  • CPU (Central Processing Unit): executes instructions, arithmetic/logic, control.
  • RAM: volatile primary memory.
  • Storage: HDD (magnetic, moving parts) or SSD (flash, no moving parts).
  • Motherboard: main circuit board housing CPU, RAM; connectors for GPU, storage.
  • GPU: accelerates graphics & complex math.
  • Power Supply: converts & distributes electrical power.
  • I/O Devices: keyboards, mice, monitors, printers, speakers.

Primary Storage vs Secondary

  • Primary (RAM): volatile, fast, temporary.
  • Secondary: non-volatile, larger, slower (magnetic tape/disk, optical, SSD, USB).
Magnetic vs Semiconductor Memory
  • Magnetic Core (historical): non-volatile, heavy, slow, high power.
  • Semiconductor: volatile (RAM), light, fast, low power, cheaper—best for small/fast memory.
Secondary Media Types
  • Magnetic Tape: sequential access; cheap archives.
  • Magnetic Disk (HDD): direct/random access; platters.
  • Floppy Disk: flexible, low-capacity removable.
  • Magnetic Drum: rotating cylinder, very fast random access (historic).

Input Devices

  • Keyboard, Mouse, Touchscreen, Scanner, Microphone, Webcam, Joystick.

Output Devices

  • Monitor, Printer, Speaker, Projector, Headphones, LED/LCD indicator lights.

Memory Hierarchy & Types

Main Categories

  • Internal / Primary (fast, small) vs External / Secondary (large, persistent).
RAM (Random Access Memory)
  • Volatile, read/write.
  • Types: SRAM (static, faster, costlier, no refresh), DRAM (dynamic, slower, needs refresh), SDRAM, RDRAM, DDR (SDRAM, DDR2/3/4…)
ROM (Read-Only Memory)
  • Non-volatile; data written once or few times.
  • Masked ROM (MROM): programmed at fabrication.
  • PROM: programmable once by user.
  • EPROM: erasable with UV light, then rewritable.
  • EEPROM/Flash: electrically erasable byte-wise; convenient updates.
Cache Memory
  • Very small, high-speed buffer storing frequently accessed data to shorten average access time.
Virtual Memory
  • Secondary storage (disk) used to simulate additional RAM, allowing larger programs to run.
Sequential Access Concept
  • Data read/written linearly (e.g., tape); contrasts with random/direct access (disk).

Software Categories

System Software

  • Operating System (OS): manages hardware, provides platform (Windows, macOS, Linux).
  • Device Drivers: translate OS commands to hardware-specific actions (printers, GPUs).
  • Utilities: maintenance tools (disk cleanup, backups).

Application Software

  • Productivity (MS Office, Google Workspace).
  • Graphics (Adobe Photoshop, Illustrator).
  • Multimedia (VLC, Adobe Premiere Pro).
  • Database (MS Access, MySQL front-ends).
  • Web Browsers (Chrome, Edge).
  • Communication (Outlook, Zoom, Slack).
  • Gaming (Fortnite, Steam).
  • Educational (learning management, tutorial games).
  • Entertainment (media players, streaming, VR apps).

Operating System Functions

  1. Process Management
    • Create/schedule/terminate processes; allocate CPU & other resources; enable multitasking.
  2. Memory Management
    • Track usage of RAM, allocate & deallocate; implement virtual memory.
  3. File System Management
    • Organize directories, control access, metadata.
  4. Device Management
    • Interface with peripherals via drivers.
  5. User Interface
    • CLI, GUI, touch, voice—enables interaction.
  6. Security & Access Control
    • Authentication, authorization, encryption, auditing.
  7. Networking
    • Protocol stacks, resource sharing, internet connectivity.

Multiprogramming

  • Technique where multiple programs reside in memory simultaneously; CPU switches among them to increase utilization and throughput.

Multitasking

  • Rapid context switches give illusion of concurrent execution on single CPU; users interact with several apps simultaneously.

Concurrent Execution

  • Overlapping execution timelines (multitasking, multiprocessing, parallelism).

Context Switch

  • OS saves state (registers, PC, stack) of current process and loads state of next; essential for multitasking.

Process Termination

  • Normal exit, user kill, error/crash; OS reclaims resources.

Process Scheduling Concepts

  • Selects next process from Ready Queue and allocates CPU.
  • Goals: maximize performance, fairness, resource utilization.
  • Algorithms mentioned: First-Come-First-Served (FCFS), Shortest Job/Shortest Remaining, Round-Robin, Priority Scheduling.
Key Scheduling Metrics
  • Arrival Time (AT): when process enters ready queue.
  • Burst Time (BT): CPU time needed for execution.
  • Completion Time (CT): when process finishes.
  • Turn-Around Time (TAT): TAT=CT−ATTAT = CT - AT or TAT=BT+WTTAT = BT + WT.
  • Waiting Time (WT): total time spent in ready queue awaiting CPU.
  • Response Time (RT): first time CPU is allocated minus arrival (initial latency).

Example table (sample values from transcript):

  • ΣCT=90\Sigma CT = 90 for 5 processes → Average CT=18\text{Average CT} = 18 etc. (full computation referenced but not explicitly required).

Digital Security Basics

  • Protect systems/networks/data from unauthorized access/attacks.
  • Measures: strong passwords, encryption, timely updates/patches.

Practical & Ethical Considerations

  • Automation and AI increase efficiency but raise concerns over job displacement and bias.
  • Data reliability and accuracy crucial for critical fields (medicine, finance).
  • Security lapses can cause privacy breaches; ethical duty to safeguard data.
  • Environmental impact: energy usage of large data centers vs efficiency gains from miniaturization.