It’s impossible to imagine life without a computer nowadays. We do our work, entertain ourselves, and find out what we need to know via computers. Sometimes we forget that the smartphone is just a palm-sized version of our desktop PC.

While the term computer can apply to virtually any device that has a microprocessor in it, most people think of a computer as a device that receives input from the user through a mouse or keyboard, processes it in some fashion, and displays the result on a screen. The hardware and software within computers have evolved at a circuit-snapping pace in the past few decades — the bulky desk-crushing machines from the early ’80s look nothing like the featherweight touchscreen tablets of today.

Compared to those of the late 20th-century, today’s modern computers are also a lot more interconnected thanks to the unrelenting sprawl of the internet and various web technologies. And this very connectedness has altered the computers themselves. Gone are the days of dial-up modems that beeped their way to text-based bulletin board systems. Now, computers use WiFi and broadband connections to blaze their way through multimedia content from live streaming news to movies to multi-player games and much more.

We can categorize computers in two ways: based on data handling capabilities and size. All the computers that are developed are not alike rather they have different designs and features. Some computers have a very high capacity as well as working speed; however, some are slow. Depending upon the requirements, computers are being developed.

• Analogue Computer
• Digital Computer
• Hybrid Computer

1) Analogue Computer

Analog computers are designed to process analog data. Analog data is continuous data that changes continuously and cannot have discrete values. We can say that analog computers are used where we don’t need exact values always such as speed, temperature, pressure, and current.

Analog computers directly accept the data from the measuring device without first converting it into numbers and codes. They measure the continuous changes in physical quantity and generally render output as a reading on a dial or scale. Speedometers and mercury thermometers are examples of analog computers

Advantages of using analog computers:

• It allows real-time operations and computation at the same time and continuous representation of all data within the rage of the analog machine.
• In some applications, it allows performing calculations without taking the help of transducers for converting the inputs or outputs to digital electronic form and vice versa.
• The programmer can scale the problem for the dynamic range of the analog computer. It provides insight into the problem and helps understand the errors and their effects.

Types of analog computers

• Slide Rules: It is one of the simplest types of mechanical analog computers. It was developed to perform basic mathematical calculations. It is made of two rods. To perform the calculation, the hashed rod is slid to line up with the markings on another rod.
• Differential Analysers: It was developed to perform differential calculations. It performs integration using wheel-and-disc mechanisms to solve differential calculations.
• Castle Clock: It was invented by Al-Jara. It was able to save programming instructions. Its height was around 11 feet and it was provided with a display of time, the zodiac, and the solar and lunar orbits. This device also could allow users to set the length of the day as per the current season.
• Electronic Analogue Computer: In this type of analog computer, electrical signals flow through capacitors and resistors to simulate physical phenomena. Here, the mechanical interaction of components does not take place. The voltage of the electrical signal generates the appropriate displays.

2) Digital Computer

A digital computer is designed to perform calculations and logical operations at high speed. It accepts the raw data as input in the form of digits or binary numbers (0 and 1) and processes it with programs stored in its memory to produce the output. All modern computers like laptops and desktops including smartphones that we use at home or office are digital computers.

Advantages of digital computers:

• It allows you to store a large amount of information and retrieve it easily whenever you need it.
• You can easily add new features to digital systems.
• Different applications can be used in digital systems just by changing the program without making any changes to hardware
• The cost of hardware is less due to the advancement in IC technology.
• It offers high speed as the data is processed digitally.
• It is highly reliable as it uses error correction codes.
• Reproducibility of results is higher as the output is not affected by noise, temperature, humidity, and other properties of its components.

3) Hybrid Computer

The hybrid computer has features of both analog and digital computers. It is fast like an analog computer and has memory and accuracy like digital computers. It can process both continuous and discrete data. It accepts analog signals and converts them into digital form before processing. So, it is widely used in specialized applications where both analog and digital data are processed. For example, a processor is used in petrol pumps that converts the measurements of fuel flow into quantity and price. Similarly, they are used in airplanes, hospitals, and scientific applications.

Advantages of using hybrid computers:

• Its computing speed is very high due to the all-parallel configuration of the analog subsystem.
• It produces precise and quick results that are more accurate and useful.
• It can solve and manage big equations in real-time.
• It helps in the online data processing.

Based on the size, the computer can be of five types:

1) Supercomputer

Supercomputers are the biggest and fastest computers. They are designed to process a huge amount of data. A supercomputer can process trillions of instructions in a second. It has thousands of interconnected processors.

Supercomputers are particularly used in scientific and engineering applications such as weather forecasting, scientific simulations, and nuclear energy research. The first supercomputer was developed by Roger Cray in 1976.

Characteristics or applications of supercomputers:

• It can decrypt your password to enhance protection for security reasons.
• It produces excellent results in animations.
• It is used for virtual testing of nuclear weapons and critical medical tests.
• It can study and understand climate patterns and forecast weather conditions. It can run in NOAA’s system (National Oceanic and Atmospheric Administration) that can execute any type of simple and logical data.
• It helps in designing flight simulators for pilots at the beginner level for their training.
• It helps in extracting useful information from data storage centers or cloud systems. For example, in insurance companies.
• It has played a vital role in managing the online currency world such as the stock market and bitcoin.
• It helps in the diagnosis of various critical diseases and in producing accurate results in brain injuries, strokes, etc.
• It helps in scientific research areas by accurately analyzing data obtained from exploring the solar system, satellites, and movement of Earth.
• It is also used in a smog control system where it predicts the level of fog and other pollutants in the atmosphere.

2) Mainframe computer

Mainframe computers are designed to support hundreds or thousands of users simultaneously. They can support multiple programs at the same time. It means they can execute different processes simultaneously. These features of mainframe computers make them ideal for big organizations like the banking and telecom sectors, which need to manage and process a high volume of data.

Mainframe computers are designed to support hundreds or thousands of users simultaneously. They can support multiple programs at the same time. It means they can execute different processes simultaneously. These features of mainframe computers make them ideal for big organizations like banking and telecom sectors, which need to manage and process a high volume of data that requires integer operations such as indexing, comparisons, etc.

Characteristics of Mainframe Computers:

• It can process a huge amount of data, e.g. millions of transactions in a second in the banking sector.
• It has a very long life. It can run smoothly for up to 50 years after proper installation.
• It gives excellent performance with large-scale memory management.
• It can share or distribute its workload among other processors and input/output terminals.
• There are fewer chances of error or bugs during processing in mainframe computers. If any error occurs it can fix it quickly without affecting the performance.
• It can protect the stored data and other ongoing exchanges of information and data.

Applications of mainframe computers:

• In health care, it enabled hospitals to maintain a record of their millions of patients to contact them for treatment or related to their appointment, medicine updates, or disease updates.
• In the field of defense, it allows the defense departments to share a large amount of sensitive information with other branches of defense.
• In the field of education, it helps big universities store, manage, and retrieve data related to their courses, admissions, students, teachers, employees, and affiliated schools and colleges.
• In the retail sector, the retail companies that have a huge customer base and branches use mainframe computers to handle and execute information related to their inventory management, customer management, and huge transactions in a short duration.

It is a midsize multiprocessing computer. It consists of two or more processors and can support 4 to 200 users at one time. Mainframe computers are used in institutes and departments for tasks such as billing, accounting, and inventory management. A minicomputer lies between the mainframe and microcomputer as it is smaller than the mainframe but larger than a microcomputer.

Characteristics of mainframe or minicomputer:

• It is lightweight which makes it easy to carry and fit anywhere.
• It is less expensive than mainframe computers.
• It is very fast compared to its size.
• It remains charged for a long time.
• It does not require a controlled operational environment.

Applications of minicomputers:

A minicomputer is mainly used to perform three primary functions, which are as follows:

• Process control: It was used for process control in manufacturing. It mainly performs two primary functions that are collecting data and feedback. If any abnormality occurs in the process, it is detected by the minicomputer and necessary adjustments are made accordingly.
• Data management: It is an excellent device for small organizations to collect, store and share data. Local hospitals and hotels can use it to maintain the records of their patients and customers respectively.
• Communications Portal: It can also play the role of a communication device in larger systems by serving as a portal between a human operator and a central processor or computer.

The personal computer has developed rapidly because of its small size, convenient use, low production cost, and low price. PC computing speed can reach hundreds of thousands to millions of instructions per second, which can meet the requirements of data processing and scientific computing in production, scientific research, and life.

PC can also be subdivided into the following types:

• Desktop computers—a case put under or on a desk. The display may be optional, depending on use. Very small computers of this kind may be integrated into the monitor.
• Rackmount computers—the cases of these computers fit into 19-inch racks and maybe space-optimized and very flat. A KVM switch or built-in remote control (via LAN or other means) can be used to gain console access.
• In-car computers (carputers)—built into automobiles, for entertainment, navigation, etc.
• Laptop Computers and notebook computers—portable and all in one case.
• Tablet computers—like laptops, but with a touch-screen, entirely replacing the physical keyboard.
• Smartphones, smartbooks, and Palmtop computers—small handheld personal computers with limited hardware specifications.
• Programmable calculator—like small handhelds, but specialized in mathematical work.
• Video game consoles—fixed computers built specifically for entertainment purposes.
• Handheld game consoles—the same as game consoles, but small and portable.

4) Workstation

A workstation is a single-user computer that is designed for technical or scientific applications. It has a faster microprocessor, a large amount of RAM, and high-speed graphic adapters. It generally performs a specific job with great expertise; accordingly, they are of different types such as graphics workstations, music workstations, and engineering design workstations.

Characteristics of workstation computer:

• It is a high-performance computer system designed for a single user for business or professional use.
• It has a larger storage capacity, better graphics, and a more powerful CPU than a personal computer.
• It can handle animation, data analysis, CAD, audio and video creation, and editing.

Any computer that has the following five features, can be termed as a workstation or can be used as a workstation.

• Multiple Processor Cores: It has more processor cores than simple laptops or computers.
• ECC RAM: It is provided with Error-correcting code memory that can fix memory errors before they affect the system’s performance.
• RAID (Redundant Array of Independent Disks): It refers to multiple internal hard drives to store or process data. RAID can be of different types, for example, there can be multiple drives to process data or mirrored drives where if one drive does not work then the other starts functioning.
• SSD: It is better than conventional hard-disk drives. It does not have moving parts, so the chances of physical failure are very less.
• Optimized, Higher-end GPU: It reduces the load on the CPU. E.g., the CPU has to do less work while processing the screen output.

5) Microcomputer

The microcomputer is also known as a personal computer. It is a general-purpose computer that is designed for individual use. It has a microprocessor as a central processing unit, memory, storage area, input unit, and output unit. Laptops and desktop computers are examples of microcomputers. They are suitable for personal work that may be making an assignment, watching a movie, or an office for office work.

Characteristics of a microcomputer:

• It is the smallest in size among all types of computers.
• A limited number of software can be used.
• It is designed for personal work and applications. Only one user can work at a time.
• It is less expensive and easy to use.
• It does not require the user to have special skills or training to use it.
• Generally, comes with a single semiconductor chip.
• It is capable of multitasking such as printing, scanning, browsing, watching videos, etc.

Computer Components

There are 5 main computer components that are given below:

• Input Devices
• CPU
• Output Devices
• Primary Memory
• Secondary Memory

The operations of computer components are given below:

• 1) Inputting: It is the process of entering raw data, instructions, and information into the computer. It is performed with the help of input devices.
• 2) Storing: The computer has primary memory and secondary storage to store data and instructions. It stores the data before sending it to the CPU for processing and also stores the processed data before displaying it as output.
• 3) Processing: It is the process of converting the raw data into useful information. This process is performed by the CPU of the computer. It takes the raw data from storage, processes it, and then sends back the processed data to storage.
• 4) Outputting: It is the process of presenting the processed data through output devices like monitors, printers, and speakers.
• 5) Controlling: This operation is performed by the control unit that is part of the CPU. The control unit ensures that all basic operations are executed in the right manner and sequence.