Classification Of Computer

On the basis of size:

Modern digital computers come in a variety of sizes and configurations. Based on their sizes, computers are divided into four groups:

• Microcomputers:
  A microcomputer is a compact, less expensive, single-user digital computer that includes a processor, an input device, an output device, a storage device, and software. Since they are independent machines, they may be joined to form a network of computers that can be utilized by several users. The examples use Apple Macintosh and IBM PCs with Pentium processors. Microcomputers include cellphones, notebooks, tablet computers, handheld computers, desktop computers, and laptops.
• Minicomputers:
  Smaller than mainframe computers, minicomputers are mid-range computers. Its operational environment, technology, and knowledge were all comparable to those of the mainframe. It costs less and takes up fewer office spaces. Mini computers are reasonably priced. They are used in schools, workplaces, labs, and corporate settings.
• Mainframe Computers:
  Computers with multiple users, several programs, and great performance are known as mainframes. A mainframe is a big computer that has a ton of memory and incredibly quick processing speed. Computers were exceedingly expensive, and there were only a few professionals who knew everything about them. Major corporate applications are processed in addition to their use for scientific and military purposes.
• Supercomputers:
  Supercomputers are extremely smart and potent pieces of machinery that can quickly process intricate computations. The largest and fastest computer currently in use. It has extremely huge memory and quick processing power. It is used to anticipate natural disasters including earthquakes, cyclones, weather changes, tides, etc. in addition to its conventional uses in scientific and military activities. The majority of supercomputers are capable of fault tolerance, or the ability to autonomously recover from failure.

On the basis of data:

• Analog computer:
  By creating physical conditions that are comparable to mathematical problems, an analog computer may function. It uses information in the form of physically changeable quantities that are continuously changing, such as pressure, temperature, revolution, sound speed, or voltage. Essentially, it is a measurement tool or piece of equipment. A very good example of a device that uses information in analog form is a speedometer on a car. It displays on a meter and transforms the rate of a shaft's rotation into a numerical approximation of speed. Analog computers benefit from the ability to accept data directly from the measuring equipment's without any conversion because analog data is acquired through a measurement procedure. This feature along with its ability to process data at high speeds makes these machines useful as controlling devices in oil references, paper and steel mills, military weapons system, etc.
• Digital computer:
  A digital computer uses discrete data to function (0 and 1). It uses computation and counting to function. The digital computers are perfectly suited for processing data since they can handle alphabetical and numerical data with accuracy and speed. It is a multifunctional computer. It is programmable. It is accessible to regular users. Digital devices include things like speedometers, watches, and other gadgets. Examples of digital computers include the IBM desktop PC, the Dell laptop, and the Acer notebook.
• Hybrid computer:
  A hybrid computer is a computer system that combines the capabilities of analog and digital computers into one. This capacity is most important when it is desired to process analog data that has been collected digitally. The airport's passenger check-in system is a relatively common application. The weight of the passenger's luggage is recorded by a weighing device, and the information is sent to check-in software to determine if it exceeds the weight limit or not. In this case, the check-in program produces an excess baggage fee for the traveler.

Classification of Micro-computer:

• Desktop Computer or Personal Computer (PC): 
  It is the sort of microcomputer that is most universal. It is a standalone device that may be placed on a desk, hence the name "desktop." Its three visible components are a keyboard, a display, and a CPU. It is affordable and appropriate for usage by individuals at home, small businesses, and organizations. PC makers include Apple, Microsoft, HP, Dell, and Lenovo.
• Notebook Computers or Laptop:
  The ability to move a desktop-capable computer that is the size of a notebook and rests silently on a person's lap has been made possible through technological advancement. It aims to satisfy the needs of organization executives who must carry out their duties from home. Most laptops have all the functions of desktop computers. It uses extremely little power and doesn't heat up as much. It can run on AC or DC power. There are no expansion slots on it. It's challenging to upgrade laptops.
• Handheld Computer or Personal Digital Assistant (PDA):
  Handheld computers are portable computers that are tiny enough to be held in the hand. It is made to offer features for managing personal information, such as a calendar, address book, memos, and more. Being extremely convenient to carry, these computers are widely used today. It accepts touch screen input, contains electronic writing pad and light sensitive electronic pen.

Reference

Ghishing, Er.Ashim. Computer Science. Kathmandu, Nepal: Benchmark , 2008.