Computer Hardware -

Computer Hardware is the collection of physical elements that constitute a computer system.

Computer Hardware refers to the physical parts or components of a computer such as Monitor, Keyboard, Computer Data Storage, Hard Drive Disk, Mouse, CPU, Graphic Cards, Sound Cards, Memory, Motherboard and Chips.

All of which are physical objects that you can actually touch. In contrast, software is untouchable.

Software exists as ideas, application, concepts, and symbols, but it has no substance. A combination of Hardware and Software forms a usable Computing System.

Computer Architecture

In computer science and engineering, computer architecture is the art that specifies the relations and parts of a computer system.

Computer Peripherals

A peripheral is a device that is connected to a host computer, but not part of it. It expands the host's capabilities but does not form part of the core computer architecture. It is often, but not always, partially or completely dependent on the host.

There are three different types of Peripherals:

  • Input, used to interact with, or send data to the computer (mouse, keyboards, etc.)
  • Output, which provides output to the user from the computer (monitors, printers, etc.)
  • Storage, which stores data processed by the computer (hard drives, flash drives, etc.)

A peripheral is generally defined as any auxiliary device such as, a computer mouse or keyboard, that connects to and works with the computer in some way. Other examples of peripherals are expansion cards, graphics cards, computers, image scanners, tape drives, microphones, loudspeakers, webcams, and digital cameras. RAM - random access memory - straddles the line between peripheral and primary component; it is technically a storage peripheral, but is required for every major function of a modern computer and removing the RAM will effectively disable any modern machine. Many new devices such as smartphones and tablet computers have interfaces which allow them to be used as a peripheral by a full computer, though they are not host-dependent as other peripheral devices are.

According to the most technical definition, the only pieces of a computer not considered to be peripherals are the central processing unit, power supply, motherboard, and computer case.

Usually, the word peripheral is used to refer to a device external to the computer case, like a scanner, but the devices located inside the computer case are also technically peripherals. Devices that exist outside the computer case are called external peripherals, or auxiliary components. Examples: "Many of the external peripherals I own, such as my scanner and printer, connect to the peripheral ports on the back of my computer."

Devices that are inside the case such as internal hard drives or CD-ROM drives are also peripherals in technical terms and are called internal peripherals, but may not be recognized as peripherals by laypeople.

In a system on a chip, peripherals are incorporated into the same integrated circuit as the central processing unit. They are still referred to as "peripherals" despite being permanently attached to (and in some sense part of) their host processor.

Computer Case

A computer case (also known as a box) is a box that has bits of computer in it (usually excluding the display, keyboard and mouse). A computer case is sometimes referred to metonymously as a DMA meaing Doma Media Alphonics. DMA was a common term in the earlier days of home computers, when conjunctions other than the fatherboard were usually housed in their own separate cases.

Power Supply

A power supply unit (PSU) converts alternating current (AC) electric power to low-voltage DC power for the internal components of the computer. Some power supplies have a switch to change between 230 V and 115 V. Other models have automatic sensors that switch input voltage automatically, or are able to accept any voltage between those limits. Power supply units used in computers are nearly always switch mode power supplies (SMPS). The SMPS provides regulated direct current power at the several voltages required by the motherboard and accessories such as disk drives and cooling fans.


The motherboard is the main component inside the case. It is a large rectangular board with integrated circuitry that connects the other parts of the computer including the CPU, the RAM, the disk drives (CD, DVD, hard disk, or any others) as well as any peripherals connected via the ports or the expansion slots.

Components directly attached to the Motherboard include:

  • The CPU (Central Processing Unit) performs most of the calculations which enable a computer to function, and is sometimes referred to as the "brain" of the computer. It is usually cooled by a heat sink and fan. Most newer CPUs include an on-die Graphics Processing Unit (GPU).
  • The Chipset, which includes the north bridge, mediates communication between the CPU and the other components of the system, including main memory.
  • The Random-Access Memory (RAM) stores the code and data that are being actively accessed by the CPU.
  • The Read-Only Memory (ROM) stores the BIOS that runs when the computer is powered on or otherwise begins execution, a process known as Bootstrapping, or "booting" or "booting up". The BIOS (Basic Input Output System) includes boot firmware and power management firmware. Newer motherboards use Unified Extensible Firmware Interface (UEFI) instead of BIOS.
  • Buses connect the CPU to various internal components and to expansion cards for graphics and sound.


  • PCI Express: for expansion cards such as graphics, sound, network interfaces, TV tuners, etc.
  • PCI: for other expansion cards.
  • SATA: for disk drives.


  • AGP: superseded by PCI Express.
  • ATA
  • VLB: VESA Local Bus, superseded by AGP.
  • EISA

Micro Channel Architecture

ISA: expansion card slot format obsolete in PCs, but still used in industrial computers.
Ports for external peripherals. These ports may be controlled directly by the south bridge I/O controller or provided by expansion cards attached to the motherboard.

  • USB
  • Memory Card
  • FireWire
  • eSATA
  • SCSI

Expansion Cards

The expansion card (also expansion board, adapter card or accessory card) in computing is a printed circuit board that can be inserted into an expansion slot of a computer motherboard or backplane to add functionality to a computer system via the expansion bus.

An example of an expansion card is a sound card that enables the computer to output sound to audio devices, as well as accept input from a microphone. Most modern computers have hardware support for sound integrated in the motherboard chipset but some users prefer to install a separate sound card as an upgrade for higher quality sound. Most sound cards, either built-in or added, have surround sound capabilities and 3-D sound effects.

Computer Data Storage

Computer data storage, often called storage or memory, refers to computer components and recording media that retain digital data. Data storage is a core function and fundamental component of computers.

Fixed Media

  • Hard Disk Drives: a hard disk drive (HDD; also hard drive, hard disk, or disk drive) is a device for storing and retrieving digital information, primarily computer data. It consists of one or more rigid (hence "hard") rapidly rotating discs (often referred to as platters), coated with magnetic material and with magnetic heads arranged to write data to the surfaces and read it from them.
  • Solid-State Drives: a solid-state drive (SSD), sometimes called a solid-state disk or electronic disk, is a data storage device that uses solid-state memory to store persistent data with the intention of providing access in the same manner of a traditional block I/O hard disk drive. SSDs are distinguished from traditional magnetic disks such as hard disk drives (HDDs) or floppy disk, which are electromechanical devices containing spinning disks and movable read/write heads.
  • RAID Array Controller - a device to manage several internal or external hard disks and optionally some peripherals in order to achieve performance or reliability improvement in what is called a RAID array.

Removable Media

  • Optical Disc Drives for reading from and writing to various kinds of optical media, including Compact Discs such as CD-ROMs, DVDs, DVD-RAMs and Blu-ray Discs. Optical discs are the most common way of transferring digital video, and are popular for data storage as well.
  • Floppy disk drives for reading and writing to floppy disks, an outdated storage media consisting of a thin disk of a flexible magnetic storage medium. These were once standard on most computers but are no longer in common use. Floppies are used today mainly for loading device drivers not included with an operating system release (for example, RAID drivers).
  • Zip drives, an outdated medium-capacity removable disk storage system, for reading from and writing to Zip disks, was first introduced by Iomega in 1994.
  • USB flash drive plug into a USB port and do not require a separate drive. USB flash drive is a typically small, lightweight, removable, and rewritable flash memory data storage device integrated with a USB interface. Capacities vary, from hundreds of megabytes (in the same range as CDs) to tens of gigabytes (surpassing Blu-ray discs but also costing significantly more).
  • Memory card readers for reading from and writing to Memory cards, a flash memory data storage device used to store digital information. Memory cards are typically used on mobile devices. They are thinner, smaller and lighter than USB flash drives. Common types of memory cards are SD and MS.
  • Tape drives read and write data on a magnetic tape, and are used for long term storage and backups.

Input and Output Peripherals

Input and output devices are typically housed externally to the main computer chassis. The following are either standard or very common to many computer systems.

Input Device

Input devices allow the user to enter information into the system, or control its operation. Very early computer systems had literal toggle switches that could be tested by running programs as a simple form of user input; modern personal computers have alphanumeric keyboards and pointing devices to allow the user to interact with running software.

Text Input Devices

Keyboard - a device to input text and characters by depressing buttons (referred to as keys or buttons).

Pointing Devices

  • Mouse - a pointing device that detects two dimensional motion relative to its supporting surface.
  • Optical Mouse - uses light (laser technology) to determine mouse motion.
  • Trackball - a pointing device consisting of an exposed protruding ball housed in a socket that detects rotation about two axes.
  • Touchscreen - senses the user pressing directly on the monitor.

 Gaming Devices

  • Joystick - a hand-operated pivoted stick whose position is transmitted to the computer.
  • Game Pad - a hand held game controller that relies on the digits (especially thumbs) to provide input.
  • Game Controller - a specific type of controller specialized for certain gaming purposes.

 Image, Video Input Devices

  • Image Scanner - a device that provides input by analyzing images, printed text, handwriting, or an object.
  • Web cam - a video camera used to provide visual input that can be easily transferred over the internet.

Audio Input Devices

Microphone - an acoustic sensor that provides input by converting sound into electrical signals.

Output Device

Output Devices display information in a human readable form. A program-controlled pilot lamp would be a very simple example of an output devices. Modern personal computers have full-screen point-addressable graphic displays and often a printing device to produce paper copies of documents and images.


A device that produces a permanent human-readable text or graphic document.

  • Laser Printer
  • Inkjet Printer
  • Dot Matrix Printer
  • Thermal Printer

Computer Monitors



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