Information Technology Infrastructure – Overview of Computers

Computer

An electronic, programmable device that accepts input, processes data, stores data, and produces output based on instructions.

Four Basic Functions of a Computer

Input, Processing, Storage, and Output.

Microcomputer

A small, low-cost, single-user digital computer containing a CPU, input/output units, storage, and software; can operate stand-alone or in a network.

Personal Computer (PC)

A general-purpose microcomputer intended for direct use by an individual; PCs typically run Windows, while Macs run macOS.

Desktop Computer

The most common type of PC; a stand-alone system designed to sit on a desk, consisting of a monitor, keyboard, and system unit.

Portable Computer

Any computer designed to be moved easily and that includes a built-in display and keyboard.

Laptop / Notebook

A portable PC with full desktop functionality, battery power, and small size that can rest on a user’s lap.

Netbook

A lightweight, low-cost notebook optimized for web-based tasks such as email, streaming, and web surfing.

Ultrabook

Intel-branded class of high-end, thin, and light sub-notebooks designed for reduced bulk without sacrificing performance or battery life.

Chromebook

A personal computer running Chrome OS, built to work primarily online with applications and data stored in the cloud; an example of a thin client.

Personal Digital Assistant (PDA)

Also called a palmtop; a handheld device that served as a personal information manager—now largely replaced by smartphones.

Tablet

A mobile computer with screen, circuitry, and battery in one unit, operated mainly through a touchscreen and virtual keyboard.

Smartphone

A mobile phone that includes advanced computing capability and connectivity beyond basic feature phones.

Minicomputer

Mid-range computer smaller and cheaper than a mainframe yet more powerful than a PC; used for scientific, engineering, and business tasks.

Mainframe

A very large, expensive computer capable of supporting hundreds or thousands of concurrent users and executing multiple programs simultaneously.

Supercomputer

One of the fastest, most expensive computers, used for intensive calculations such as weather forecasting and scientific simulations.

Server (Functionality Class)

A computer that provides services, resources, or data to other computers over a network.

Workstation (Functionality Class)

A high-performance computer designed for technical or scientific applications, typically used by one person at a time.

Information Appliance

A device specialized for a specific digital task (e.g., e-readers, smart speakers) with a user-friendly interface.

Embedded Computer

A computer integrated into another device to control functions, often with real-time constraints (e.g., in cars, appliances).

Analog Computer

A computer that represents data with continuously variable physical quantities.

Digital Computer

A computer that processes data represented in discrete binary form (0s and 1s).

Hybrid Computer

A system combining features of analog and digital computers to exploit advantages of both.

General-Purpose Computer

A computer designed to perform a wide variety of tasks using stored programs.

Special-Purpose Computer

A computer built to perform a specific, dedicated task.

Speed (Computer Capability)

The ability of a computer to process data at very high rates, measured in microseconds or faster.

Accuracy (Computer Capability)

The high precision with which computers perform calculations and operations.

Reliability (Computer Capability)

The consistent performance of computers with minimal errors or failures.

Versatility (Computer Capability)

The ability of computers to perform a broad range of tasks and applications.

Storage (Computer Capability)

The capacity of computers to store vast amounts of data for immediate or future use.

Limitations of a Computer

Dependent on user input, cannot make independent decisions, lacks feelings, and cannot implement actions by itself.

First-Generation Computers (1946-1959)

Used vacuum tubes and magnetic drums; large, costly, generated much heat, calculated in milliseconds.

Vacuum Tube

Glass electronic component used in first-generation computers to control electric current; bulky and heat-producing.

Second-Generation Computers (1959-1965)

Replaced vacuum tubes with transistors, reducing size and heat; introduced magnetic storage and assembly language.

Transistor

A semiconductor device that amplifies or switches electronic signals; key component of second-generation computers.

Third-Generation Computers (1964-1971)

Employed Integrated Circuits (ICs), improving speed, reliability, and storage while reducing size.

Integrated Circuit (IC)

A chip containing many transistors and electronic components; invented by Jack Kilby and Robert Noyce.

Fourth-Generation Computers (1971-1980)

Based on microprocessors, enabling miniaturization, multiprocessing, and graphical user interfaces (GUI).

Microprocessor

A single chip integrating CPU functions, performing arithmetic and logic operations in a computer system.

Fifth-

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