Hardware can be defined as the physical and tangible components that the computer is made of.

Hardware has a permanent shape and structure that is not easily altered or changed.

It is the component of the computer that stores and executes software.

A typical computer usually has the following hardware components.

  1. CPU

  2. Main memory

  3. Secondary storage device

  4. Input device

  5. Output device

Let's take a closer look at each hardware component.

CPU(Central processing unit)

When a computer is executing the task a program instructed it to do, we say the computer is running or executing the program.

The CPU is the part when the program is executed. The CPU performs all kinds of data processing functions.

The CPU is the hardware part of the computer that carries out the instruction of the computer program.

CPU itself has two components, which are: ALU (Arithmetic Logic Unit) and control unit. 

1. Arithmetic logic unit(ALU): This is the component of the CPU that performs processing calculations. ALU is sub-divided into two sections: The arithmetic and logic section

  • Arithmetic section: This perform basic operation like addition, subtraction, multiplication, and division in computer instructions.

  • Logic section: it is responsible for performing logic operations such as selecting, comparing, matching, and merging data. The logic section determines if one value is greater, lesser, or equal to the other.

2. Control unit: As the name suggests, The control unit controls all operations of the CPU. The control unit directs the operation of other units but is not involved in the actual data processing. 

The following are functions of the control unit

  1. Controls all units of the computer

  2. It communicates with both input devices and output devices

  3. It also communicates with ALU and the main memory

Input device

Input, as you probably know,  is any information that the computer collects from input devices. An input device is a device that is used to enter data into the computer. 

An input device is any device that allows you to get data into the computer. A computer cannot only understand information from the input device.

The following are input devices:

  1. Keyboard

  2. Mouse

  3. Light pen

  4. Bar code scanner

  5. Magnetic ink character recognition (MICR)

  6. Optical Mark Recognition(OMR)

  7. Optical character recognition(OCR)

  8. Joystick

  9. Trackball

If you are not familiar with the aforementioned input devices, refer to this post

Main memory

School is the work area of the teacher. Likewise, the main memory is the work area of the computer. 

The main memory stores the program that is being executable, as well as the data the program is using. CPU can easily access data stored in the main memory.

For example, suppose you are using a presentation package to write a presentation, both the presentation package and the presentations are stored in the main memory

Main memory can be divided into ROM and RAM.

1. RAM(Random access memory): This is considered the fastest and most expensive memory. 

RAM is the computer memory that stores loaded programs. It is the temporary holding place for data and instructions

RAM is volatile, that is, data stored in RAM are lost when the computer is switched off.

As can be seen below, inside your computer, RAM is stored in Chips.

2. ROM(Read-only memory): As the name suggests, this memory is only readable by the CPU. Data stored in this memory cannot be modified.

ROM is the permanent memory that contains instructions and programs needed to start and control the operation of the system.

ROM's data are usually written by the manufacturer. ROMs are used to store special data and instructions that the computer needs for booting.

Unlike RAM, ROM is non-volatile. This means instruction and data stored in ROM are not lost or erased if the computer is unpowered. ROM is relatively cheaper than RAM.

Secondary memory

This type of memory is usually called external memory or backup memory. They are non-volatile because they are used for storing data permanently.

This kind of memory can hold data for a long period even when there is no power to the computer.

The contents of secondary memory are not directly accessible to the CPU. Rather, they are first transferred to the main memory where they are directly accessible to the CPU.

The disk drive is arguably the most popular secondary storage device. A disk drive stores data by magnetically encoding it upon a circular disk

Most computers usually have a disk drive that enables them to read instructions from a disk.

In the 20th century, a disk drive called floppy disk drive was the prevalent secondary storage. 

A floppy disk drive stores data by magnetically encoding it into a small disk called a floppy disk

Floppy disks are thin, circular disks enclosed in rigid plastic shells. Floppy disks are easily removable.

Floppy disks can only hold a small amount of data. Moreover, it is not unreliable.

For this reason, the use of floppy disk drives has declined dramatically, in favour of more superior devices like USB drives and optical disks.

USB drives are small portable devices used to store digital data. USB stored data in a special solid-state memory called flash memory.

USB drives are plugged into the computer USB port and they appear to the system as a disk drive. USB drives are inexpensive and portable in that they are small enough to be carried in your pocket. 

Another type of secondary memory is optical devices. Optical discs like CD (Compact disc) and DVD (Digital Versatile Disc) are also used for data storage.

In an optical device, data are stored on and series of pits on the disk surface. Then, CD and DVD drives detect this encoded data using laser illumination and read this data.

Output device

Once data has been input and processed, it would be of little use if it can not be easily obtained from the system. 

For this reason, a computer should be connected to an output device. An output device is a device that lets you receive data sent to the computer.

The output device is the direct opposite of the input device. So, while the input device input data into the system, the output device receive information from the computer.

More specifically, an output device is a device that converts information into a human-readable form. 

The output device, connected to the computer, allows you to transfer data from the computer in audio, text, or visual format.

Monitor and printer are two of the most popular output devices. So, let's look at both output device


This is the most popular output device. A monitor is similar to a television set. And like a television set, the monitor gives a graphical display of the computer's output. 

A monitor allows you to visualize the data from the computer. 

Various kinds of monitors exist: They include Cathode ray tubes (CRT), Liquid crystal display(LCD), Light-emitting diodes(LED), and plasma panels.

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Printers are output devices dedicated to creating paper copies from the computer.

They are usually connected to the computer and can be used to produce paper output (hard copies).

They are divided into two types: Impact and non-impact printers.

1. Impact printers: These print characters by striking them on the ribbon, which is them impacted on a paper.

Impact printers rely on typewriting printing mechanisms, in which a hammer strikes the paper through a ribbon to create paper copies.

Impact printers have the advantage of being economically efficient for bulk printing.

On the flip side, impact printers might cause nose pollution due to their noise.

Drum printers, chain printers, daisy wheel printers and dot matrix printers all are examples of impact printers 

2. Non-impact printers: These print characters without the use of ribbon.

They don't have to touch the paper to print.
These printers produce less noise than impact printers. 

In addition, non-impact printers print more quickly than impact printers.

Non-impact printers include ink-jet printers, laser printers, and thermal printers. There you have it. Do you have any questions? 

Please let me know in the comments section.

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