What is computer hardware?

A computer system is made of a combination of hardware and software. The software consists of a set of instructions that instruct the computer to perform a task. It can be system software or application software. Whereas, hardware is the part of a computer that can be touched. In other words, computer hardware consists of the physical components of a computer. The internal parts of a computer are called components and the external hardware components are called peripherals.

Computer hardware consists of the following types of components:

• A central processing unit (CPU)/ processor
• Storage devices
• Input devices
• Output devices

Basic computing model

The working of a computer differs from model to model. However, the basic function of every computer remains the same. Below are the four functions that occur in every computer system:

• Receiving input: The computer receives information/ data from input devices that is, keyboard or mouse.
• Information processing: After receiving the information, the computer processes it by using arithmetic and logical operations.
• Display output: Finally, the computer displays the output to the end-user using output devices such as the monitor or printer.
• Store information: The computer stores the processed information in storage devices such as hard disks and compact disks.

The Central Processing Unit

The CPU is the central part of the computer. It is the brain of a computer. It handles all the functions such as data processing operations, storing results, and executing instructions. CPU consists of five components: control unit (CU), arithmetic logic unit (ALU), registers, buses, and clock.

Control unit

The control unit of the CPU controls the data transfer and instructions processing part. It instructs the memory, arithmetic unit, logic unit, input devices, and output devices on how to handle the instructions.

Arithmetic logic unit

The ALU is a digital circuit that handles all the arithmetic and logic operations when an instruction is passed into the computer system. It performs arithmetic operations like addition, subtraction, multiplication, logic OR, logic AND, and division. ALU works in binary digits (only 0s, and 1s).

Registers

The arithmetic logic unit is made of registers. Registers are high-speed circuits that store data, instructions, and memory addresses when the data is being processed in the ALU.

Buses

In a register, the data is stored as a unit of eight bits. Every bit is transferred from one register to another using a single wire. When eight such wires combine, a bus is formed. Buses are of three types, data bus, control bus, and address bus.

Clock

Clock calculates and allots a fixed time slot to every micro-operation performed by the CPU. The speed is measured in terms of megahertz. It is used for the synchronization of different components and instructions.

Memory

Memory is the part of the computer, typically a storage area where the computer stores the instructions before and after processing them. The computer memory is divided into smaller parts or blocks. Each part represents a unique address and the range of these addresses depends on the size of the memory. Computer memory is broadly classified into two types: primary memory and secondary memory.

Primary Memory

The primary memory is the memory that is included within the computer. That means it is a part of the computer. It can be referred to as internal memory. A computer has two types of primary memory: random-access memory (RAM) and read-only memory (ROM).

Random-access memory (RAM)

RAM is the internal memory used to store data and instructions while processing programs. It is a read/ write memory and volatile. That means, if the computer switches off or the power supply cuts off, then the data stored in RAM gets deleted. The storage capacity of RAM can be 640KB or above.

Further, there are three types of RAM: dynamic random access memory (DRAM), static random access memory (SRAM), and synchronous dynamic random access memory (SDRAM).

Read-only memory (ROM)

ROM is a nonvolatile memory which means that the data stored in ROM is not lost if the computer shuts down. It is a permanent memory. Usually, it stores the instructions required to start a computer. The size of ROM differs in every computer. The storage capacity of ROM begins at 24KB and goes up to 256KB.

Further, there are four types of ROM, masked read-only memory (MROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), and electrically erasable programmable read-only memory (EEPROM).

Secondary Memory

Apart from the internal memory, the computer also uses external storage devices (secondary memory devices) to store data. It is not compulsory to use these hardware devices. However, they help transfer data between multiple computers or store and retrieve data whenever required. Below are some of the commonly used secondary memory devices:

• Floppy disks: Floppy disks are small, flexible storage devices made of plastic and coated with magnetic material. They can be single-sided or double-sided. The data on the floppy disk is recorded in the form of magnetized particles.
• Hard disk/ hard drive: Hard disk drives are removable magnetic disks. They hold more data than floppy disks and are faster.
• Optical disk drives: It is a disk drive that reads and writes data using laser light or electromagnetic waves.
• Compact disks: Compact disks are pre-pressed optical compact disks that consist of data. They can read data but not write or erase data.
• USB: A USB (USB flash drive) or pen drive is a portable device that reads and writes data using the USB port in computers. They are compact and easy to carry.

Input devices

Input devices are the physical components that send data, information, or instructions to a computer. There are two types of input devices: basic and special input devices. Basic input devices are those that are required for a computer or PC to operate. However, special input devices are not necessarily needed for a computer to operate.

Below are examples of the commonly used input devices:

• Keyboard: Keyboard is the most popular form of input device used to input data to a computer system. It consists of keys as numeric keys, alphabet keys, function keys, special character keys, and non-printable control keys.
• Mouse: A mouse is a pointing device that controls the navigation of the cursor on the computer screen. It is a tiny device that is rolled using hands and placed on a flat surface. The cursor on the screen moves as per the direction of the mouse. A mouse can be wired or wireless.
• Joystick: Joystick is a pointing device that controls the cursor position on the PC screen. It looks like a stick and has a ball with lower and upper ends. A joystick is mainly used in computer-aided designing and playing games.
• Scanner: A scanner is used to transfer information from paper to the computer system. It scans the printed material and converts it into a specific file format.

Other types of input devices include a trackball, light pen, and a bar code scanner.

Output devices

Output devices are the devices used to display or print information from the computer system. They are connected externally or built-in the computer system.

Some of the commonly used output devices include:

• Monitor or visual display unit (VDU): A monitor is the main output device in a computer. It creates images using dots (pixels) arranged in rectangular form. Monitors can be monochrome or colorful.
• Printer: Printers are used to print information on paper. There are several types of printers such as daisy wheel printer, inkjet printer, dot matrix printer, and drum printer.
• Speakers: Speakers are output devices that produce audio in the form of sound waves. They can be wired or wireless.
• Plotter: Plotters are used to print high-quality images, graphics, and drawings. The common types of plotters are flatbed plotters, drum plotters, and inkjet plotters.

Context and Applications

Fundamentals of hardware concepts are studied in grade 10 under the information and technology subject. However, the basic concepts of this topic are also asked in several competitive exams.

Practice Problems

Q1) Which of the following are the examples of output devices?

1. Monitor, blu-ray, CD-ROM
2. Monitor, printer
3. Speaker, low-level scanner, solid-state drives (SSD)
4. Joystick, dual in-line memory module (DIMM)

Answer: Option b

Explanation: Output devices return or display the result obtained after the computer processes a task. Monitor, printer, speaker, plotter are examples of output devices. From the above options, only option b lists output devices. The rest options have a combination of output devices, input devices, or memory devices.

Q2) Which of the following is a function of input devices?

1. They interact directly with the computer.
2. They display the data stored on the mainframe computer.
3. They interpret the stored program from the operating system and sound card.
4. They print data on DIMM 

Answer: Option a

Explanation: Input devices take input from users and directly interact with the computer to send the instructions.

Q3) When a computer shuts down, in which type of memory the content stored is lost?

1. RAM
2. UEFI ROM
3. Operating system
4. Wikiversity storage

Answer: Option a

Explanation: RAM is volatile. Consequently, its content is erased when the computer switches off.

Q4) Which hardware component is included in a CPU?

1. ALU
2. CU
3. Buses
4. All of the above

Answer: Option d

Explanation: A CPU comprises five components that are, arithmetic logic unit, control unit, registers, buses, and clock.

Q5) Which of the following is not an example of computer hardware?

1. Excel
2. Monitor
3. Printer
4. Scanner

Answer: Option a

Explanation: Excel is a software application used to store data in the form of tables.

Common Mistakes

Learners often get confused between input and output devices. Consequently, it is necessary to learn the basic difference between input and output devices and remember it using an example.

Related Concepts

• Basic concepts of system software
• Motherboard circuitry
• Difference between computer hardware and software
• Network and internet