Unit 1: Introduction to Computer

Introduction

A computer is an electronic device that accepts input, processes it according to a set of instructions called a program, and produces meaningful output. It can also store data for future use. The word computer comes from the Latin word computare, meaning to calculate.

A computer system has three core capabilities:

• Input — accept data from the user or another device.
• Processing — perform calculations or logical operations on the data.
• Output — present the result in a usable form (screen, file, sound, etc.).

Digital and analog computers

Computers are broadly classified by how they represent data:

Type	How it represents data	Example uses
Analog	Continuous physical quantities (voltage, etc.)	Thermometer, speedometer, ECG machine
Digital	Discrete values, typically 0s and 1s	Laptops, smartphones, servers
Hybrid	Combines analog inputs with digital processing	Medical scanners (CT/MRI), avionics

Most computers we use today are digital because of their speed, accuracy, and ability to store huge amounts of data.

Characteristics of computer

• Speed — performs billions of operations per second.
• Accuracy — produces correct results as long as input is correct (GIGO: Garbage In, Garbage Out).
• Diligence — never gets tired or bored.
• Versatility — performs different types of tasks (calculations, communication, graphics).
• Storage — stores massive amounts of data for future use.
• Automation — can run programs without continuous human help.
• Reliability — operates consistently over long periods.

History of computer

The development of computers happened in stages over centuries:

• Abacus (~2400 BC) — the earliest known calculating tool.
• Pascaline (1642) — Blaise Pascal’s mechanical adder.
• Difference Engine (1822) and Analytical Engine (1837) — designed by Charles Babbage, the Father of the Computer.
• Ada Lovelace — wrote the first algorithm for Babbage’s machine, considered the first programmer.
• Tabulating Machine (1890) — Herman Hollerith used punched cards for the US census.
• ENIAC (1946) — first general-purpose electronic digital computer.
• UNIVAC (1951) — first commercial computer.
• Microprocessor (1971) — Intel 4004, the first single-chip CPU.

Generations of computer

Computers evolved through five major generations:

Generation	Period	Technology	Example
First	1940 – 1956	Vacuum tubes	ENIAC, UNIVAC
Second	1956 – 1963	Transistors	IBM 1401, IBM 7090
Third	1964 – 1971	Integrated Circuits (ICs)	IBM 360, PDP-8
Fourth	1971 – 1985	Microprocessors	IBM PC, Apple Macintosh
Fifth	1985 – now	AI, ULSI, parallel	Modern PCs, servers, AI

Each new generation made computers smaller, faster, cheaper, and more powerful.

Classification of computer

Computers can be classified by size and capability:

• Supercomputer — extremely fast, used for weather forecasting, simulations (e.g. Frontier, Fugaku).
• Mainframe — large machines used by banks, airlines, and governments for bulk data processing.
• Minicomputer — mid-range, used in research and small businesses.
• Microcomputer — personal computers, laptops, desktops.
• Workstation — high-performance PC used by engineers and designers.
• Embedded systems — special-purpose computers inside cars, TVs, washing machines.

Data and program representation in computer

Internally, a computer represents everything in binary — sequences of 0s and 1s.

• Bit — a single binary digit (0 or 1).
• Byte — 8 bits, stores one character.
• Number systems used by computers:
  • Binary (base 2) — only 0 and 1.
  • Octal (base 8) — 0–7.
  • Decimal (base 10) — 0–9 (used by humans).
  • Hexadecimal (base 16) — 0–9, A–F.

Programs are also stored in binary, as machine code that the CPU can execute.

Character codes

• ASCII — 7-bit code for English characters.
• Unicode (UTF-8) — represents almost every language on Earth.

Applications of computers

Computers are used in nearly every field today:

• Education — e-learning, online classes, virtual labs.
• Healthcare — patient records, imaging (CT, MRI), telemedicine.
• Banking — ATMs, online banking, fraud detection.
• Business — accounting, inventory, customer relationship management.
• Entertainment — movies, games, music, streaming.
• Science and engineering — simulations, research, design.
• Government — citizen services, taxation, e-governance.
• Communication — email, chat, video conferencing.
• Transportation — GPS, ticket booking, autonomous vehicles.