The Ever-Changing Computers

Computer

A programmable device that processes, stores, and retrieves data based on software instructions; turns the modern world into a “global village.”

Origin of the word “Computer”

Originally referred to a person who manually calculated numbers, before it became associated with machines.

Digital Computer

Processes data step by step using binary (0s and 1s); most modern computers belong to this type.

Analog Computer

Represents data as continuous physical quantities (like voltage); used for tasks like tide prediction before being phased out.

James Thomson

19th-century inventor who worked on analog computation; developed mechanical devices like the wheel-and-disc integrator.

Vannevar Bush

Developed the Differential Analyzer, a large analog computer for solving differential equations.

First Generation Computers

Used vacuum tubes (1940s–1950s); huge machines like ENIAC and UNIVAC I that filled entire rooms but had limited power.

Vacuum Tube

A three-terminal device (cathode, grid, plate) that controlled current in first-generation computers.

Second Generation Computers

Used transistors instead of vacuum tubes (1950s–1960s); smaller, faster, cheaper, and more reliable.

Transistor

A three-terminal solid-state electronic device that controls electric current or voltage; revolutionized electronics.

Third Generation Computers

Based on integrated circuits (1960s); introduced keyboards, monitors, and operating systems for multitasking.

Integrated Circuit (IC)

Invented by Jack Kilby in 1958; combines multiple electronic circuits into one small semiconductor chip.

Fourth Generation Computers

Based on microprocessors (1970s–present); tiny chips containing CPU, memory, and input/output controls.

Microprocessor

First introduced by Intel 4004 (1969); placed the functions of a computer on a single silicon chip.

Input Unit

Devices like keyboard and mouse that allow users to send instructions to the computer in digital form.

Output Unit

Devices like monitors and printers that display or present the results of computer processing.

Central Processing Unit (CPU)

The “brain” of the computer; interprets, processes, and executes instructions through its components.

Memory Unit

Stores input data, instructions, and output results; uses bits and bytes as measurement.

Control Unit

Directs the flow of data inside the CPU and converts human language into machine language.

Arithmetic Logic Unit (ALU)

Handles mathematical calculations and logical operations like comparisons and decision-making.

Operating System (OS)

A set of programs that manage hardware and software resources, making computers usable.

Advantages of OS

Provides abstraction, allows execution of programs, and offers a user-friendly environment.

Disadvantages of OS

Can be volatile (data loss), expensive, and vulnerable to security threats.

Microsoft Windows

A family of graphical OS introduced in 1985; dominates the PC/laptop market worldwide.

Mac OS

Apple’s desktop OS designed for Macintosh computers; offers GUI, multitasking, and memory security.

Android

A mobile OS developed by Google (2008); the most widely used mobile operating system.

iOS

Apple’s mobile OS (2007); known for smooth performance and secure ecosystem.