Comprehensive Overview of Computer Systems, Evolution, and Classification

INTRODUCTION TO COMPUTER OVERVIEW

• Integration into Everyday Life: Computers have integrated into daily thinking and activities, serving applications from complex frontline research calculations and engineering simulations to teaching, book printing, and recreational gaming.

• Ease of Use: The ability to process, store, and retrieve data painlessly has made computers unavoidable in business and office environments.

• Boundaries of Application: The areas of application are limited only by human imagination and creativity. Any task that can be carried out systematically can be performed by a computer.

• Essential Knowledge: For an educated person today, understanding a computer's strengths, weaknesses, and internal structure is essential.

THE PERVASIVENESS OF COMPUTERS

• Universal Presence: Computing technology surrounds modern life in the form of smartphones, sophisticated gadgets, and ATMs. The term "Internet" is familiar even to school beginners.

• Industrial and Domestic Control: Automation has evolved from computer-controlled factories to cars, and now computer-controlled homes are a reality.

• Modern Context: Literacy in computer terminology is now a standard trait of the "computer-kid of today."

FORMAL DEFINITION OF A COMPUTER

• Definition: A computer is an electronic device capable of performing various operations according to a set of instructions known as a program.

• Capabilities:

  • Process data millions of times faster than humans.

  • Store data and information in its memory.

  • Produce desired results based on processed input.

  • Tasks include playing games, railway reservations, weather forecasting, error detection, and controlling spacecraft flight.

DATA VS. INFORMATION

• Primary Use: A computer functions essentially as a data processor.

• Data: Refers to raw facts and figures. Examples include names like 'Mohan', dates like $1977$, or grades like 'A', and numbers such as $-162.9$ and $+752$. Data is processed to form information.

• Information: Meaningful data derived after aggregation and summarization. For instance, "Mohan, whose roll number is 1977, has got grade A" is information because it conveys meaning.

• Relationship: Data represents what enters the computer (input), and Information represents what leaves it (output).

• Information Processing Cycle: The systematic process of transforming data into information.

THE FUNCTIONING OF A COMPUTER: THE IPO CYCLE

• Human Analogy: Humans function by receiving a request or ingredient (input), performing the task (process), and delivering the result (output).

  • Activity 1: Mother's request for cake/pastries (Input) -> Going to bazaar and purchasing (Process) -> Purchased items (Output).

  • Activity 2: Desire to call friend (Input) -> Dialing and connecting (Process) -> Chatting with friend (Output).

  • Activity 3: Ingredients like $\frac{1}{2}$ cup water, $\frac{1}{2}$ tsp tea-leaves, $\frac{1}{2}$ tsp sugar, $\frac{1}{2}$ cup milk (Input) -> Boiling and adding ingredients (Process) -> Prepared tea (Output).

• Universal Rule: Every task follows the Input-Process-Output (IPO) cycle. Computers are no exception; they require input, process it, and produce output.

FUNCTIONAL COMPONENTS OF A COMPUTER

• Input Unit: Responsible for taking input and converting it into binary form ($1$ and $0$) so the computer can understand it.

• Central Processing Unit (CPU): Often called the "brain" of the computer, it guides, directs, and governs performance. It consists of the Arithmetic Logic Unit (ALU) and the Control Unit (CU).

• Output Unit: Converts electronic binary signals from the CPU into human-understandable forms (characters, graphics, audio, or visuals).

• Main Memory: Holds the input and intermediate output during processing.

DETAILED COMPONENTS OF THE SYSTEM

Input Unit

• Hardware Devices: Keyboard, Mouse, Magnetic Ink Character Reader (MICR), Optical Mark Reader (OMR), Optical Character Reader (OCR), Joystick, etc.

• Binary Language: Computers operate on electricity and understand only two stages: ON ($1$) or OFF ($0$), also described as High or Low voltage.

• Input Composition: Consists of both Data (the object of action) and Instructions (the action to be taken). For example: "Add $2$ and $3$" where $2$ and $3$ are data and "Add" is the instruction.

• GIGO Principle: "Garbage In, Garbage Out." This signifies that the correctness of the output is directly dependent on the correctness and aptness of the input.

Central Processing Unit (CPU)

• Arithmetic Logic Unit (ALU): Performs arithmetic operations ($+$, $-$, $*$, $/$) and logical operations (<, >, $=$, $\le$, $\ge$, $\neq$). Logical operations return results as either TRUE or FALSE, enabling decision-making capabilities.

• Control Unit (CU): Acts as the supervisor. It controls the flow of data between input/output devices and memory. It fetches instructions from memory, decodes them to determine the operation, and coordinates the ALU and memory until the operation is complete. It executes instructions one after the other in sequence.

Output Unit

• Function: Translates binary code into human-readable characters or visuals.

• Examples: Visual Display Unit (VDU/Monitor), Printer, Plotter, Speakers, Speech Synthesizer, Coder, etc.

Computer Memory

• Characteristics: Unlike human memory, computer primary memory is temporary (volatile). It clears when power is switched off or after a task is completed to make room for new tasks.

• Memory Cells: Basic devices capable of storing a symbol selected from a set. Bits (Binary Digits $0$ or $1$) are the most elementary units.

• Measurement Units:

  • $1$ Nibble = $4$ Bits

  • $1$ Byte = $8$ Bits (Smallest unit representing a character)

  • $1$ KB = $2^{10} = 1024$ Bytes

  • $1024$ KB = $1$ MB ($2^{20}$ Bytes)

  • $1024$ MB = $1$ GB ($2^{30}$ Bytes)

  • $1024$ GB = $1$ TB ($2^{40}$ Bytes)

  • $1024$ TB = $1$ PB (Peta Byte)

  • $1024$ PB = $1$ EB (Exa Byte)

  • $1024$ EB = $1$ ZB (Zetta Byte)

  • $1024$ ZB = $1$ YB (Yotta Byte)

  • $1024$ YB = $1$ Bronto Byte

  • $1024$ Bronto Bytes = $1$ Geop Byte

Secondary Memory

• Used for permanent storage because primary memory is volatile. Examples include Hard Disks, CD-RWs, and Pen Drives.

HARDWARE AND SOFTWARE

Hardware

• The physical and tangible components (electronic, electrical, and mechanical equipment).

• Peripherals: Devices surrounding the system unit (Keyboard, mouse, printer, etc.).

• Core Hardware Categories: Input devices, memory, storage devices, CPU, and output devices.

Software

• Sets of programs that govern operations and make hardware run.

• Operating System (OS): An interface between the user and the hardware. It manages resources, controls components, and provides a user interface. Metaphorically, it acts as a "secretary" who decides how, when, and what to do based on the "boss's" (user's) orders. Major versions include Single-user, Multiuser, Batch processing, and Multiprocessing.

• Language Processors: Necessary because computers only understand machine language ($0, 1$).

  • Assembler: Converts assembly language to machine language.

  • Interpreter: Converts High Level Language (HLL) line-by-line. Reports errors immediately. Must remain in memory during execution.

  • Compiler: Converts the entire HLL program at once. Reports all errors with line numbers. Produces an "object program," after which the compiler is no longer needed in memory.

• Application Software: Programs for specific tasks (e.g., railway reservation).

  • Customized (Bespoke): Tailor-made for a specific user's requirements.

  • General (Generic): Developed for widespread use (e.g., Office packages).

STRENGTHS AND WEAKNESSES OF COMPUTERS

Strengths

• Speed: Modern computers execute millions of instructions per second.

  • Storage: High capacity in small spaces (e.g., a $4.7$-inch CD-ROM can hold $33$ volumes of Encyclopedia Britannica; Blu-Ray discs can hold up to $100$ GB).

• Accuracy: Calculations and comparisons are precise if hardware functions correctly.

• Reliability: Immune to tiredness, boredom, and fatigue.

• Versatility: Capable of repetitive tasks, hazardous jobs in hostile environments, and handling diverse data types (graphics, audio, visual).

Weaknesses

• Lack of Decision-Making: Computers cannot decide for themselves.

• IQ Zero: They are "dumb machines" requiring minute-by-minute instructions for every step.

Additional Terminology

• Firmware: Prewritten programs permanently stored in Read-Only Memory (ROM) (e.g., BIOS). They are not easily modified by users.

• Liveware: Refers to the people associated with or benefiting from computer systems.

EVOLUTION OF COMPUTING DEVICES

• Abacus ($3000$ BC): Developed by Mesopotamians/Chinese. Uses beads on rods to perform addition and multiplication using place value.

• Napier’s Logs and Bones ($1550$-$1617$): Numbered rods used for multiplication.

• Pascal’s Adding Machine ($1642$): Gear-based wheels for quick addition/subtraction with automatic carry-transfer.

• Leibnitz Calculator ($1671$): Improved Pascal's machine to include multiplication and division.

• Jacquard’s Loom ($1801$): Used punched cards to automate weaving; introduced the era of storing/retrieving information.

• Babbage’s Difference Engine ($1822$): Designed by Charles Babbage to calculate logarithmic tables and mathematical functions using finite differences.

• Analytical Engine ($1833$): The conceptual ancestor of modern computers with a central processor, memory, and input/output. It featured stored information modification and comparisons.

• First Programmer ($1834$): Ada Byron, Lady Lovelace, created plans to calculate Bernoulli numbers using the Analytical Engine.

• Hollerith’s Machine ($1887$): Electromechanical tabulator using punched cards for the $1880$ US Census; reduced processing time from $10$ years to $3$ years. Led to the founding of IBM.

• Stored Program Concept ($1946$): Proposed by Dr. John von Neumann; data and instructions stored in the same read-write memory addressable by location.

GENERATIONS OF MODERN COMPUTERS

• First Generation ($1940$-$1956$): Used Vacuum Tubes. Huge, expensive, and unreliable. Generated high heat requiring large air conditioners. Used Machine Language. Examples: ENIAC, EDVAC, EDSAC, UNIVAC-I.

• Second Generation ($1956$-$1963$): Used Transistors. Smaller, faster, and consumed less electricity. Used Assembly Language. Examples: IBM $1400$ and $7000$ series.

• Third Generation ($1964$-$1971$): Used Integrated Circuits (ICs) on silicon chips. Introduced $256$-bit RAM. High-level languages were developed. Examples: IBM-$360$, ICL-$1900$.

• Fourth Generation ($1971$-Present): Used LSI and VLSI (Large and Very Large Scale Integration) microprocessors. Development of the personal computer (PC) and portable devices. Storage reached Tera Byte ($TB$) levels.

• Fifth Generation (Present and Beyond): Focused on Artificial Intelligence (AI), parallel processing, and superconductors for faster information transfer. Applications include voice recognition and advanced robotics.

EVOLUTION OF STORAGE AND DISPLAY

Storage Technologies

• Punched Card ($1890$): Mechanical reading.

• Magnetic Drum ($1932$): Early memory using electromagnetic pulses.

• Magnetic Tape ($1951$): Popular backup media replacing thousands of punched cards.

• Hard Disk Drive ($1958$): Magnetized circular platters. Became popular in the $1990$s.

• Floppy Disk ($1969$): Flexible magnetic disk. Sizes: $8$, $5\frac{1}{2}$, $1.44$ inches. Capacity around $80$ KB initially.

• Optical Media ($1980$s-$1990$s): CD followed by DVD ($8$-$10$ times CD capacity).

• Flash Drive ($1998$): Solid state memory.

• Cloud (21st Century): Data stored on multiple 3rd party servers over the Internet.

Display Technologies

• CRT ($1897$): Cathode Ray Tube used in early TVs and computers.

• LCD ($1963$): Liquid Crystal Display; prominent in the $1990$s.

• Plasma ($1964$): Wide range of contrasts/colors.

• Touchscreen ($1965$): Mass adoption post-iPhone ($2007$).

• OLED ($1987$): Introduced to consumers in $2009$.

CLASSIFICATION OF COMPUTERS

By Purpose

• Special-Purpose: Designed for a specific task (e.g., embedded controllers). Efficient but not versatile.

• General-Purpose: Can run different programs for countless applications.

By Operation Principle

• Analog: Operates on continuous physical quantities (voltage, temperature). Lower accuracy. Use case: electronic weighing scales.

• Digital: Operates on discrete binary data ($0, 1$). Faster and more accurate.

• Hybrid: Combines both (e.g., medical monitors for vital signs, weather forecasting).

Digital Computers by Configuration

• Embedded: Tiny chips in appliances (TVs, washing machines).

• Microcomputers (PCs): Single-microprocessor systems. Categories include Handheld/Mobile (Smartphones), Portable (Laptops, PDA), Desktop, and Workstations (higher math/memory for industrial use).

• Minicomputers: Mid-range servers, multiuser systems with more power than microcomputers.

• Mainframe: Multiuser, multiprocessor systems for huge data volumes (e.g., banks, hospitals).

• Supercomputers: Most powerful. Use parallel processors for billions of instructions per second. Examples: CRAY X-MP, PARAM.

SUPERCOMPUTING IN INDIA

• Political Context: In the mid-$1980$s, the US refused to sell India a second supercomputer. This spurred Indian scientists to develop indigenous models.

• Key Laboratories and Models:

  • NAL (Bangalore): Developed Flosolver Mk3 (half as powerful as CRAY but $\frac{1}{10}$ the cost).

  • ANURAG (Hyderabad): Developed PACE (Processor for Aerodynamic Computation and Evaluation).

  • C-DAC (Pune): Developed the PARAM series. PARAM $8000$ ($1991$) achieved $1$ Gigaflop performance at a fraction of the world market cost ($2$ crore).

• Successors: PARAM $8600$, $9000$, PADMA, Cluster, and YUVA-II.

• Current Standing: PARAM YUVA-II was listed as the $9^{th}$ fastest in Asia Pacific and $44^{th}$ in the world.