Introduction to computer hardware components

Hardware is the physical part of a computer. The soft ware components executes or runs  the hardware. Computer hardware can also be seen in embedded systems in automobiles, microwave ovens, CD players, DVD players and many more devices. 

Motherboard

The motherboard is the body or mainframe of the computer. It is through motherboard all other components interface. It is the central circuit board making up a complex electronic system. A motherboard provides the electrical connections and by which the other components of the system communicate. The mother board includes many components such as: central processing unit (CPU), random access memory (RAM), firmware, and internal and external buses.

Central Processing Unit

The Central Processing Unit (CPU; sometimes just called processor) is a machine that can execute computer programs. It is sometimes referred to as the brain of the computer.

CPUs use four steps  their operation. They are, fetch, decode, execute, and write back. The first step, fetch, involves retrieving an instruction from program memory. In the decode step, the instruction is broken up into parts that have significance to other portions of the CPU. During the execute step various portions of the CPU, such as the arithmetic Logic Unit (ALU) and the Floating Point Unit (FPU) are connected so they can perform the desired operation. The final step, write back, simply writes back the results of the execute step to some form of memory.

Random Access Memory

Random access memory (RAM) is fast-access memory.  RAM is cleared when the computer is turned off. RAM attaches directly to the motherboard, and is used to store programs that are currently running. RAM is a set of integrated circuits that allow the stored data to be accessed in any order. Hence the name, random comes to it. There are  different classifications of RAM, which include, writable & read-only, static & dynamic, volatile & non-volatile, etc.

Firmware

Firmware is loaded from the Read only memory (ROM). It is a computer program that is embedded in a hardware device, for example a microcontroller. As the name suggests, firmware is an intermediate entity between hardware and software. Like software, it is a computer program which is executed by a microprocessor or a microcontroller. But at the same time it is also tightly linked to a piece of hardware. Most devices attached to modern systems are special-purpose computers in their own right, running their own software. Some of these devices store that software (“firmware”) in a ROM within the device itself.

Power Supply

The power supply is the device that supplies power to all the components in the computer.  A power supply unit holds a transformer, voltage control and usually a cooling fan. The power supply converts about 100-120 volts of AC power to low-voltage DC power for the internal components to use. The most common computer power supplies are built in compact with the ATX form factor. This enables different power supplies to be interchangable with different components inside the computer. ATX power supplies also are designed to turn on and off using a signal from the motherboard and provide support for  functions such as standby mode.

Removable Media Devices

 There are many different removable media devices. 

CD

CDs are the most common type of removable media. They are inexpensive, but having short life-span. There are a few different kinds of CDs. 

CD-ROM: It stands for Compact Disc read-only memory. They are popularly used to distribute computer software, but any type of data can be stored on them. 

CD-R : It  can only be written to once but can be read many times.

 CD-RW (rewritable) : It can be written to more than once as well as read more than once. 

Some other types of CDs that are not as popular include Super Audio CD (SACD), Video Compact Discs (VCD), Super Video Compact Discs (SVCD), PhotoCD, PictureCD, CD-i and Enhanced CD.

There are two types of devices in a computer that use CDs:

 CD-ROM drive and a CD writer. 

The CD-ROM drive used for reading a CD.

 The CD writer drive can read and write a CD. 

CD writers are much more popular  than a CD-ROM drive in modern computers. Both kinds of CD drives are called optical disc drives because the use a laser light or electromagnetic waves to read or write data to or from a CD.

DVD

DVDs (digital versatile discs) are another popular optical disc storage media format. The main uses for DVDs are video and data storage. Most DVDs are of the same dimensions as compact discs. Just like CDs there are many different variations. 

DVD-ROM has data which can only be read and not written. 

DVD-R and DVD+R can be written once and then function like a DVD-ROM. 

DVD-RAM, DVD-RW, or DVD+RW hold data that can be erased and re-written multiple times.

DVD-Video and DVD-Audio discs  refer to properly formatted and structured video and audio content respectively. 

The devices that use DVDs are very similar to the devices that use CDs. 

There are DVD-ROM drive as well as a DVD writer that work the same way as a CD-ROM drive and CD writer. Also, a DVD-RAM drive can read and write to different DVD-RAM types.

Blu-ray

Blu-ray is comparatively a newer optical disc storage media format. Its main uses are high-definition video and data storage. The disc has the same dimensions as a CD or DVD. The term “Blu-ray” comes from the blue laser used to read and write to the disc. The Blu-ray discs can store much more data than CDs or DVDs. A dual layer Blu-ray disc can store up to 50GB, which is almost six times the capacity of a dual layer DVD . Like CD and DVD drives, Blu-ray discs have similar devices used to read  and write. A BD-ROM drive can only read a Blu-ray disc and a BD writer can read and write a Blu-ray disc.

Floppy Disk

A floppy disk is a type of data storage that is composed of a disk of thin, flexible(“floppy”) magnetic storage medium encased in a square or rectangular plastic shell. Floppy disks are read and written by a floppy disk drive. Floppy disks are nowadays replaced by the optical and flash drives. Floppy disks were available in cheap rate, but had comparatively large data storage capacity during their time of dominance.  

Internal Storage

Computer hardware  keeps data inside the computer for later use and remains persistent even when the computer has no power. Such memory parts of a computer hardware is known as Internal storage . There are different types of internal storage. Hard disks are the most popular type of internal storage. Others are Solid-state drives , disk array controller etc.

Hard Disk Drive

A hard disk drive (HDD) is a non-volatile storage device which stores digitally encoded data on rapidly rotating platters with magnetic surfaces. Typical desktop hard disk drives store between 120 and 400 GB data, rotate at 7,200 rpm and have a media transfer rate of 1 Gbit/s or higher. Hard disk drives are accessed over one among a number of available bus types such as parallel ATA (also called IDE), Serial ATA (SATA), SCSI, Serial Attached SCSI, and Fibre Channel.

Solid-State Drive

A solid-state drive (SSD) is a data storage device that uses solid-state memory to store persistent data. An SSD is very similar to a hard disk drive. SSDs are used in laptops because they can be smaller than HDDs. However, SSDs are currently more expensive per unit of capacity than HDDs.

Disk Array Controller

A disk array controller is a device which manage the physical disk drives and presents them to the computer as logical units. It  implements hardware RAID. RAID means Redundant Array of Independent Drives. RAID is a technology that employs the simultaneous use of two or more hard disk drives to achieve greater levels of performance, reliability, and larger data volume sizes. A disk array controller also provides additional disk cache.

Computer Hardware Peripherals

A peripheral is a part of computer hardware that is added to a computer in order to expand its abilities. The term peripheral is used to describe those devices that are optional in nature. There are all different kinds of peripherals. The main distinction among peripherals is the way they are connected to computer. They can be connected internally or externally.

Buses

A bus is a subsystem that transfers data between computer components inside a computer or between computers. Unlike a point-to-point connection, a bus can logically connect several peripherals through the same set of wires. Each bus defines its set of connectors to physically plug devices, cards or cables together. 

There are two types of buses: internal and external

Internal buses are connections to various internal components. External buses are connections to various external components. There are different kinds of slots to which internal and external devices can connect .

Internal

Types of Slots

There are many different kinds of internal buses. Different computers come with different kinds and number of slots. It is important to know the kind and number of slots on computer before inserting a card that matches up to a slot.

PCI

PCI (Peripheral Component Interconnect) is common internal bus in modern PCs. Typical PCI cards used in PCs include: network cards, sound cards, modems, extra ports such as USB or serial, TV tuner cards and disk controllers. Video cards have outgrown the capabilities of PCI because of their higher bandwidth requirements.

PCI Express

PCI Express was introduced by Intel in 2004. It was designed to replace the general-purpose PCI expansion bus and the the used AGP graphics card interface. PCI express is not a bus but instead a point-to-point connection of serial links called lanes. PCI Express cards have faster bandwidth than PCI cards which make them more ideal for high-end video cards.

PCMCIA

PCMCIA (also referred to as PC Card) is the type of bus used for laptop computers. The name PCMCIA comes from the group who developed the standard: Personal Computer Memory Card International Association. PCMCIA was originally designed for computer memory expansion. Its useful general standard for notebook peripherals further led to many kinds of devices being made available in this form. Typical devices include network cards, modems and hard disks.

AGP

AGP (Accelerated Graphics Port) is a high-speed point-to-point channel for attaching a graphics card to a computer’s motherboard, primarily to assist in the acceleration of 3D computer graphics. AGP has been gradually replaced by PCI Express.

Types of Cards

Video Card

A video card (also known as graphics card) is an expansion card whose function is to generate and display images. Some video cards offer additional functions such as video capture, TV tuner adapter, ability to connect multiple monitors etc. They include a graphics processing unit (GPU) which is a dedicated microprocessor optimized for 3D graphics rendering. It also includes a video BIOS that contains the basic program which governs the video card’s operations and provides the instructions. These instructions allow the computer and software to interface with the card. If the video card is integrated in the motherboard, it may use the computer RAM memory. Otherwise, the cards have their own video memory called Video RAM. This kind of memory can range from 128 MB to 2 GB. A video card also has a RAMDAC (Random Access Memory Digital-to-Analog Converter) which takes responsibility for turning the digital signals produced by the computer processor into an analog signal which can be understood by the computer display. They  have outputs such as an HD-15 connector (standard monitor cable), DVI connector, S-Video, composite video or component video.

Sound Card

A sound card is an expansion card that facilitates the input and output of audio signals to/from a computer under control of computer programs. Typical uses for sound cards include providing the audio component for multimedia applications such as music composition, editing video or audio, presentation/education and entertainment. Many computers have built in sound capabilities, while others require additional expansion cards to provide for audio capability.

Network Card

A network card is an expansion card that allows computers to communicate through a network. It allows users to connect to each other either by using cables or wireless. Among various  network technologies Ethernet is popular. Every Ethernet network card has a unique 48-bit serial number called a MAC address, which is stored in ROM carried on the card. 

External

Types of Connections

USB

USB means Universal Serial Bus. It is a serial bus standard to interface devices. USB was designed to allow many peripherals to be connected using a single standardized interface socket. It improves the plug-and-play capabilities by allowing devices to be connected and disconnected without rebooting the computer. One of the other convenient features include providing of power to low-consumption devices without the need for an external power supply. Further,  USBs allow many devices to be used without requiring manufacturer specific, individual device drivers to be installed. USB is nowadays the dominating bus for connecting external devices to  computers.

Firewire

Firewire is a serial bus interface standard for high-speed communications and is a real-time data transfer component used in a personal computers. It has been adopted as the High Definition Audio-Video Network Alliance (HANA) standard connection interface for A/V (audio/visual) component communication and control. Almost all modern digital camcorders have firewire connections in them.

PS/2

The PS/2 connector is used for connecting  keyboards and mike to a PC compatible computer system. The keyboard and mouse interfaces are similar in connection with  noted difference. Open collector outputs are required on both ends of the keyboard interface to allow bidirectional communication. If a PS/2 mouse is connected to a PS/2 keyboard port, the mouse may not be recognized by the computer depending on configuration.

Devices

Removable Storage

Similar to the built-in hardware components of computers,  external CD and DVD drives can also be attached to computers. An external CD writer can be connected to the computer through USB port and acts the same way as if it was built-in to the computer. The same is true for DVD writers, Blu-ray drives and floppy drives. 

Flash drives have become very popular form of removable storage. Flash drives are usually connected through USB. They are available either in the form of USB sticks or very small and portable devices. USB flash drives are small, fast, removable, re-writable and long-lasting. Storage capacities range from 64 MB to 32 GB or more. A flash drive does not have any mechanically driven parts, so compared to a hard drive. This makes it more durable and smaller.

Non-removable Storage

Non-removable storage can be a hard drive that is connected externally. External hard drives have become very popular for backups, shared drives among many computers. External hard drives come in many shapes and sizes like flash drives . An external hard drive is usually connected by USB. A networked hard drive can  allow all computers on that network to access the drive for storage.

Input

Input devices are absolutely crucial to computers. The most common input devices are mike and keyboards. A new popular input device  replacing the mouse is touch screen. Other popular input devices include microphones, webcams and fingerprint readers. These devices are in fact built in to modern laptops and desktops. A scanner is another popular input device that might be built-in to  printer.

Output

There are lots of different kinds of output devices for a computer. The absolute most common external output device is a monitor. Other very popular output devices are printers and speakers. There are  different kinds of printers and different sizes of speakers. Monitors are connected usually through the HD-15 connector on video card. Printers are usually connected through a USB port. Speakers have their own audio out port built-in to the sound card.