Computer Hardware



Physical parts of a computer which can be seen and touched are known as Hardware. All the peripheral devices attached to the computer are hardware like keyboard, mouse, system unit, CD’s, floppies, scanners, and printers are the hardware. All the power cables, data cables, connectors, and chips are hardware.
Computer Hardware - Introduction || Motherboard - Components - Ports || Memory - Storage - Types


 The motherboard is the main component inside the system case. It holds many of the crucial electronic components of the system such as the Central Processing Unit and memory and provides connectors for other peripherals. CPU is also known as the brain of the computer which is present in the motherboard. Since the CPU is the brain of the computer, the motherboard is the central nervous system of the computer.

Components of a motherboard

Computer Hardware - Introduction || Motherboard - Components - Ports || Memory - Storage - Types


A CPU is the hardware within a computer that carries out the instructions of a computer program by performing the basic arithmetical, logical, and input/output operations of the system.


A computer bus(often simply called a bus) is an electronic pathway. Its role is to transfer data, signals, or power from one part to another part of the computer. Different types of busses are data bus, address bus and control bus.

Expansion slot

An expansion slot is a socket on the motherboard that is used to insert an expansion card(or circuit board) which allows connecting additional devices to a computer such as a video, sound, advanced graphics, ethernet, or memory.

Cooling Fan

The cooling fan is a fan present inside the system unit which keeps the computer cool by throwing the hot air outside and letting cool air into the system unit from outside.

CMOS Battery

CMOS batteries help in running the computer’s internal clock and help in changing the date of a computer regularly even if the computer is switched off. This is the reason why a computer regularly changes its date and time even when the computer is switched off. Lithium CR2032 batteries which last from 2 to 10 years depending upon the type of motherboard are best for computers. higher temperatures and longer power-off times shorten the cell life.


The ROM BIOS chip contains a small program known as firmware which holds the booting instructions of a computer. It helps in starting up the computer.

Ports of Motherboard

Computer Hardware - Introduction || Motherboard - Components - Ports || Memory - Storage - Types

Parallel port

A parallel port is a type of interface found on computers (personal and others) for containing peripherals. In computing, a parallel port is a parallel communication physical interface. It is also known as a printer port. The parallel port interface was originally known as LPT (Line Print Terminal) port.

Serial port

As the name suggests, it allows the transfer of data in a serial way. In a serial port, only one line/wire is used to transfer data. it is used for slow-speed peripherals like keyboard, mouse, modem, and others. Serial ports are slower than parallel ports.

PS/2 Port

PS/2 port was developed by IBM. It is also called a mouse port. It is used to connect a computer mouse or keyboard. It is a round connector with 6pins. A color code is used to distinguish between two ports. The keyboard port is purple and the mouse port is green.

Universal Serial Bus (USB) Port

USB was designed to standardize the connection of computer peripherals (including keyboards, pointing devices, digital cameras, printers, portable media players, disk drives, and network adapters) to personal computers, both to communicate and supply electric power. It has become commonplace on other devices such as smartphones, PDAs, and video games. USB has effectively replaced a variety of early interfaces such as serial and parallel ports as well as separate power chargers for portable devices.

FireWire Port

FireWire interface is also known as IEEE 1394 port. IEEE stands for “Institute of Electrical Engineers”. It is a serial bus interface especially created for high-speed audio and video transmission.


Computer Hardware - Introduction || Motherboard - Components - Ports || Memory - Storage - Types

It is the storage space in a computer where data and information are stored before and after processing. Data and instructions are stored in memory in the form of binary digits called bits. The bit is the smallest unit of storage and the combination of 8bits is called byte. Each byte is also referred to as a single character. The other storage capacities of memory are:
8 Bits1 Byte or 1 Character
1024 Bytes1 Kilobyte (KB)
1024 Kilobytes1 MegaByte (MB)
1024 Megabytes1 GigaByte (GB)
1024 Gigabytes1 TeraByte (TB)
1024 Terabytes1 Peta Byte (PB)
Memory is further divided into two types. They are Primary and Secondary Memory.

1. Primary Memory

The primary memory is the main memory of a computer. This is the place where our data and instructions are stored before processing and results are stored before displaying output. Memory which stores data and information currently being used by the computer is known as primary memory. It is further divided into RAM and ROM.

a. RAM (Random Access Memory)

It is a memory where data and instructions are stored temporarily. it is also known as volatile memory as data and instructions remain only till electricity is supplied there. If power is switched off, the data stored in RAM is erased by itself. A user can read from and write onto RAM. hence, it is also known as Read and Write Memory.
There are two types of RAM. They are: 
  • SRAM (Static RAM)
  • DRAM (Dynamic RAM)


SRAM stands for Static Random Access Memory and it is made up of transistors. It is called Static because it can remember or retain its memory contents without being refreshed or recharged as long as there is power. SRAM does not need to be refreshed or recharged periodically like DRAM. It is faster than DRAM but is more expensive, bigger in size, and consumes more electricity than DRAM.

ii. DRAM

DRAM stands for Dynamic Random Access Memory. It is the most common and cheapest type of memory chip. It is made of capacitors that are capable of storing the electric charge. Due to leakage of charges, the capacitors discharge gradually, and the memory cells lose their contents. DRAM has to be refreshed periodically by recharging the capacitors to retain its memory contents. it is slower than SRAM and consumes less electricity and is less expensive too.

b. ROM (Read Only Memory)

It is the memory where data and instructions are stored permanently. It is also known as non-volatile memory as data and instructions remain there even when there is no electricity supply. Data is stored in the ROM chip during the manufacturing time. The program present in ROM is known as “Firmware” and is responsible to boot the computer.
Different types of ROM are:
  • PROM (Programmable ROM)
  • EPROM (Erasable Programmable ROM)
  • EEPROM (Electrically Erasable Programmable ROM)


PROM stands for Programmable Read-Only Memory. Initially, it is the blank chip that can be written or programmed only once by using a special machine called ROM programmer or ROM burner. Once the PROM is written, it cannot be modified and becomes ROM.


EPROM stands for Erasable Programmable Read-Only Memory. It is a special chip that can be re-programmed to record different information. The data and information are erased by exposing them to intensive ultraviolet light. EPROM chips are used in product development and experimental projects.


EEPROM stands for Electrically Erasable Programmable Read-Only Memory. This type of chip can be erased and reprogrammed repeatedly with special electric pulsed. it doesn’t require a special device to write onto it. EEPROM can be reprogrammed without removing it from the computer.

2. Secondary Memory

Memory which stores data and instructions permanently for further reference is known as secondary memory. it is the permanent memory where data and information remain forever. it has a huge storage capacity of up to GB and TB. it is a non-volatile memory in nature where data and instructions remain even if there is no electricity. Different secondary storage media are Magnetic storage media, optical storage media, and flash storage media.

a. Magnetic Storage

It is a storage media in which data are stored onto the disk in the form of magnetic spots. A coating of magnetic metallic oxide like ferric oxide is done over the disks which attract the data to be deposited over them. Some of the magnetic storage media are magnetic tapes, floppy disks, hard disks, and so on.

i. Hard Disk

A hard disk is a secondary storage device of a computer. It is an air-tight sealed unit consisting of a number of magnetic disks (platters) mounted on a spindle. it was introduced by IBM in 1956 AD. At first, it was called “Winchester Disk”. Unlike floppy disks, the platters cannot be bent so they are hard disks. It is mainly used to store large volumes of data and programs permanently as it is also non-volatile in nature. The disk is divided into a number of concentric circles called tracks and these tracks are divided into invisible segments called sectors.

ii. Floppy disk

It is around and flat disk that is made up of a mylar (a plastic material) coated with magnetic material. it is read/write memory as we can read from it as well as write onto it. We can access the information from a floppy randomly. We can use floppy disks to store data and programs, backup files, transfer data from one computer to another computer, and so on. It is also called a diskette.

b. Optical Storage

It is also a nonvolatile secondary storage medium. it is a flat round disk made up of plastic polycarbonate material coated with aluminum alloy. A very fine laser beam is projected on the reflecting surface to read data from the disk. Some of the examples of optical disks are CD-ROM and DVD.


 CD-ROM stands for Compact Disk Read-Only Memory. As it is an optical storage medium, the laser beam is used to access data from the disk. It can store about 700MB of data or 80minutes of video. It is very useful in storing large amounts of data like computer software, movies, audio or video songs, and so on. Other types of CD-ROM are CD-R (Compact Disk Recordable) and CD-RW (Compact Disk Rewritable).

ii. DVD

DVD stands for Digital Versatile Disk or Digital Video Disk. It is also a type of optical memory device which has a very large storage capacity. it is also considered as the improved form of CD ROM. DVD also uses the same technology as that of CD-ROM for reading and writing data. The storage capacity of one DVD is almost 6 times more than a CD.

c. Flash Memory

It is a non-volatile, erasable, and programmable, solid-state memory that is made of semiconductor chips. it was introduced at first in the mid-1980s by Fujio Masuoka at Toshiba Corporation, Japan. it can be reprogrammed at high speed and hence the name flash. It is derived from EEPROM. In flash memory, the entire memory can be erased in a few seconds by using electric technology. Flash memory is used in many input/output and storage devices. It is also used to store data and programs in cell phones, digital cameras, and MP3 music players.

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