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Classification of Computers According to Size

Updated on July 21, 2017
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Alfred is a long-time teacher and computer enthusiast who works with and troubleshoots a wide range of computing devices.

Google exec Amanda Rosenberg modeling Google Glass.
Google exec Amanda Rosenberg modeling Google Glass. | Source

You can categorize computers by size, which leaves you with four major groups. Each group excels at their own specific function.

  • Supercomputers
  • Mainframe computers
  • Mini-computers
  • Personal computers

The supercomputer is a gigantic machine with multiple microprocessors. They are designed to perform extremely complex calculations. Miniature computers are small enough to be strung around the wrist or worn on the head. They can only perform basic functions.

Generally, larger machines have higher processing speeds while smaller ones are a better experience for personal computing.

1. Supercomputers

These are arguably the most powerful in terms of speed and accuracy. They are useful in problems that require complex mathematical computations. They are capable of trillions of instructions per second, which is calculated in floating point operations per second (FLOPS). Your personal computer is only capable of calculating millions of instructions per second (MIPS). Supercomputers can go even faster with the rate of peta FLOPS (or PFLOPS). This could bring up their processing numbers up to the quadrillion.

Supercomputers were made popular in the 1960s by Seymore Cray. They soon became the choice for complex projects. They have evolved from a grid system to a cluster system of massively parallel computing.

Cluster system computing means that machines use multiple processors in one system, rather than arrays of separate computers in a grid.

These computers are the largest in terms of size. They can occupy anything from a few feet to hundreds of feet. They also don’t come cheap as they can be priced between $200,000 to over $100 million.

Roadrunner supercomputer.
Roadrunner supercomputer. | Source

The Top Supercomputer Every Year From 2008

Name of Supercomputer
Speed in PFLOPS
Cray - USA
Tianhe - 1A
NUDT - China
K Computer
Fugitsu - Japan
Cray - USA
Tianhe - 2
NUDT - China
Tianhe - 2
NUDT - China
Tianhe - 2
NUDT - China

 Uses of Supercomputers

Because of their superiority, supercomputers are not intended for your everyday tasks. They are intended for exhaustive scientific applications that require complex and real-time processing.

  • In the field of science, researchers use these machines to compute and model properties of biological compounds like protein and human blood. They are also used to interpret new diseases and strains, and predict illness behavior and treatment.
  • The military use supercomputers to test new aircraft, tanks, and a host of weaponry and camouflage. They also use them to understand the effects they will have on soldiers and wars. These machines are also used to help encrypt and decrypt sensitive data.
  • In entertainment, supercomputers are used to help make a flawless online gaming experience. Games like World of Warcraft demand intense processing. When thousands of gamers around the world are playing, supercomputers help stabilize the game performance.
  • Meteorologists use them to simulate weather behavior. They can also be used to predict earthquakes.
  • Scientists use them to simulate and test the effects of nuclear weapon detonation.
  • Scientists also use them to simulate the events of the Big Bang and other space related projects.
  • Hollywood uses supercomputers to create realistic animations.
  • The famous supercomputers Deep Blue and Watson defeated chess Grandmaster Gary Kasparov and quiz expert Ken Jennings respectively.

Chinese Hardware Leading in Speed

2. Mainframe Computers

Mainframe computers are large and powerful machines. However, they fall short in terms of the computation ability seen in supercomputers. They are like big file servers, enabling multiple users from nearby and remote locations to access mainframe resources at the same time. Also known as big iron, these machines can handle massive amounts of of data going in and out simultaneously.

This makes them popular with businesses. They are also resilient as they are capable of operating for over 10 years without failing.

The users access the mainframe using terminals or personal computers. This can happen within the same building or via wide area network (WAN).

IBM System z9
IBM System z9 | Source

There are two types of terminals used to access mainframe computers.

  • Dumb Terminal: These do not normally have their own CPU and storage devices. This type of terminal uses the processing resources and storage within the mainframe machine. Typically, a dumb terminal consists of a monitor, a keyboard, and a mouse.
  • Intelligent Terminal: These have their own processor and can perform some tasks. For example, personal computers in banking institutions are normally used as intelligent terminals. They can access data and other services from a mainframe computer, and can also store and process data locally.

 Uses of Mainframe Computers

These machines are used in large organizations where thousands of clients have to access data simultaneously.

Examples include:

  • Performing ATM cash withdrawals and deposits. During the process, communication between the mainframe and remote computer will help accomplish the financial transactions at hand.
  • Business transactions that use credit card or pre-paid card.
  • Online electronic transactions.
  • Cloud storage.
  • Handling of patient records in major hospitals.
  • Making reservations and travel schedules for airline companies.
  • Manipulation and tallying of data for census and electoral purposes.

The price of mainframe computers, especially from IBM, start at $75,000 and can go up to $1 million.

3. Minicomputers

Minicomputers are general purpose devices without the monumental expenses associated with a larger systems. Their processing power is below that of mainframe systems but above the capabilities of personal computers.

Prototyp 1990, MicroVAX II Clone Minicomputer
Prototyp 1990, MicroVAX II Clone Minicomputer | Source

Also known as mid-range computers, these became popular in late 1960s and saw a reduction in usage by the 1990s. The first minicomputer was unveiled in 1967 by Digital Equipment Corporation and was followed later by designs from IBM and other companies.

They became popular for control related functions as opposed to computing prowess. Over the years, their usage was limited to dedicated control assignments in mid-range organizations.

Minicomputers are intended for a number of activities that include:

  • Switchboard control.
  • Dedicated applications for graphic and computer design.
  • Time-sharing, allowing multiple users to interact concurrently on a single system.
  • Control and monitoring of manufacturing activities.
  • Monitoring and control of laboratory equipment.

4. Microcomputers

Microcomputers are the smallest and least expensive systems. They have small memory, less processing power, are physically smaller, and permit fewer peripherals to be attached. They are more commonly known as personal computers or simply PCs. The term was initially used to refer to IBM compatible computers.

They became popular in the 70s and 80s, at the dawn of the microprocessor chips. These chips meant that a machine being used by one individual was now feasible.

The advent of PCs meant cheaper alternatives to more expensive and centralized systems. They were more affordable for office use and created cheaper networking environments. By the mid 1990s, they became the de facto computer of choice for offices and homes. The last 20 years have seen the proliferation of even smaller systems.

This signaled the start of the mobile age, which continued to go with the trend of smaller devices as the new century progressed. This ultimately gave birth to wearable computers and gadgets.

Categories of personal computers include:

  • Desktop computers.
  • Mobile computers.
  • Wearable computers.

An example of a personal computer as a desktop.
An example of a personal computer as a desktop.

Desktop Systems

Desktop computers are made up of separate components such as:

  • The system unit; a rectangular case that contains important parts like the motherboard, microprocessor, memory modules, disk drive, and optical drive.
  • The monitor.
  • A mouse.
  • A keyboard.

 Single Unit Systems

Single unit computers, also known as all-in-one PCs, are a subtype of desktop machines. They integrate the monitor and system unit within a single unit.

They also have connectivity to a mouse, keyboard, and other peripherals, usually through USB ports.

Nettop Systems

Nettop, which are sometimes called mini PCs, are small and cheap system units. They use less power and perform less processing.

Common features of Nettops include the Intel Atom microprocessor, 1-2 GB memory, and Wi-Fi connectivity.

Just like any other desktop, they attach to peripheral accessories via USB ports.

A nettop computer
A nettop computer

Mobile Computers

Mobile hardware have become the norm in recent years. Most users have opted for laptops and tablets due to the ease of using them on the go and not having to rely on bigger machines back home. Whereas desktop computers limit the user to local disk storage, mobile devices take advantage of online cloud storage.

Particular features that make mobile systems a favorite include:

  • Extended battery use.
  • Wi-Fi capabilities.
  • Mobility.

The most common types of mobile computers include:

  • Laptop computers.
  • Tablets.
  • Smartphones.
  • Personal Digital Assistants (PDA).

A 17 inch laptop and 10 inch netbook side by side.
A 17 inch laptop and 10 inch netbook side by side.


Laptops are lightweight mobile PCs with a thin screen. They were initially called notebook computers because of their small size. They operate on batteries.

Unlike desktops, these systems combine the microprocessor, screen, and keyboard in a single case. The screen folds down onto the keyboard when not in use.

 Ultrabooks

Ultrabooks are special laptops specifically designed to be thin and lightweight. They usually have longer lasting batteries (5 hours minimum) and have strong hardware and processing power to run any software around.

Ultrabooks also ship with the faster SSD storage in place of the slower hard disk drives that are commonly used.

 Chromebooks

Chromebooks are low-end laptops that only runs the web-based Chrome operating system. After the installation of Chrome OS, additional software can only be installed via the Chrome Web Store.

The OS allows you to achieve traditional PC functionality online. You can type documents, edit them, implement group discussions, have teleconferencing, and use basic online tools like search engines and e-mail.

These devices are increasingly targeted for users that spend most of their time online for social activities. Their hardware includes the Intel Atom microprocessor, Wi-Fi and wired network connectivity, solid state disks (SSD), and an average of five hours of battery life. They usually do not have optical drives.


 Netbooks

Netbooks can be thought of as mini laptops. They are smaller in size, price, and processing power. Just like Chromebooks, they are primarily designed for web browsing, electronic communication, and cloud computing. They are catered to users who require less powerful client computers.

Their specs are similar to Chromebooks. The biggest difference is that they can run the lightweight Linux operating system.


A tablet is a mobile computer equipped with a touch screen or hybrid screen, which allows the user to operate it by use of a digital pen or fingertip.

Most tablets today are both multi-touch and multi-tasking, making it possible to manipulate them using multiple fingers and accomplishing multiple tasks simultaneously.

Tablets are handy, especially when normal notebooks and laptops are simply too bulky for the mobile user.

An iPad mini tablet
An iPad mini tablet

 Smartphones

Back in 1996, a company called Palm Computing developed a gadget called Palm 1000. It was revolutionary in conception but did not actually build consumer excitement.

While the idea of a miniaturized computer was not new, the fact that someone had actually been able to make a device with an operating system that could work within its limitations was a huge leap forward. It was one of the biggest innovations in the tech industry.

The iPhone, released in 2007, was the first true smartphone. It became an instant hit with consumers worldwide. It started the smartphone industry that still persists today.

An iPhone.
An iPhone.

Most smartphones today use an operating system such as IOS and Android. They often have the ability to add applications. This is in contrast to regular cellular phones which only support sandboxed applications like Java games. In terms of features, smartphones support full email capabilities as well as multiple functions to serve as a complete personal organizer.

Depending on the manufacturer, other functions might include additional interfaces such as miniature QWERTY keyboards, touch screens, built-in cameras, contact management, built-in navigation software, ability to read office documents in PDF and Word file formats, media software for playing music, browsing photos, and viewing video clips.

 Personal Digital Assistants

Personal digital assistants (PDAs), also called handheld computers, pocket PCs, or palm top computers, are battery-powered devices that are small enough to carry almost anywhere.

While weaker to larger systems, these are useful for scheduling appointments, storing addresses and phone numbers, and playing games. Some have more advanced capabilities, such as making telephone calls or accessing the Internet.

PDAs seem to have been overtaken by tablets and smartphones, almost rendering them obsolete.

Wearable Computers

Like the term suggests, wearable computers, or simply wearables, are miniature devices that are designed to be worn or attached onto your body.

Wearables are designed to function as smart devices similar to smartphones. They typically provide specific functions like health monitoring.

Whereas general purpose wearables offer a fuller computing experience that includes reading emails, the lesser systems will ship as embedded devices capable of minimal functions.

Examples of these devices include smartwatches, smartglasses, smartclothes, smartshoes.

 Smartwatches

These became popular around 2013, when Samsung launched Gear, a wristwatch fitted with sensors to communicate directly with a smartphone.

Dubbed the smartphone and phablet companion, a smartwatch gives features like internet connectivity and text messaging among others.

It also provides communication between the user and other devices.

The leading tech companies in the world are all scrambling for opportunities in manufacturing smartwatches. Samsung launched Gear in 2013 and Apple has the Apple Watch. Other competitors include Sony, LG, and Google.

 Head Mounted Display

Another wearable being developed is the heads up display unit (HUD) or head mounted display unit (HMD).

This device is meant to be worn or attached to the head and uses a transparent glass display that interfaces with the human eye. It does not interfere with the users sight.

Earlier HUDs were used for military purposes. They went from using a cathode ray tube to a liquid crystal display. The technology eventually embraced laser-based projection for images and motion pictures.

The current leader in this tech is Google Glass, which permits a number of functions like voice communication and reading tweets.


 Smartware

Smartshoes and smartclothes are intended for health-related functions like measuring heart rate and waveform measurement. These devices are intended to encourage the wearer to have an active lifestyle.

Nike shoe showing the transmitter that communicates with the iPod
Nike shoe showing the transmitter that communicates with the iPod | Source

Smartshoes and smartclothes can also be used for competitive purposes, such helping athletes keep track of their running distance and speed.

One of the first initiatives into developing these devices was the partnership between Apple and Nike. They created the Nike+iPod Sports Kit, a device for measuring distance and pace by the user. It worked by having the iPod communicate to the Nike show via voice prompts.

5. Embedded Systems

Embedded devices have specialized computer chips which are built into standalone electronic hardware. This allows specific computing tasks. Embedded computers are pre-programmed and can be re-programmed to suit changing demands.

Firmware on these systems are written on permanent read-only memory (ROM) chips. An example would be the special chip embedded within a cable box that allows it provide TV services.

Embedded systems are seen in the devices and gadgets listed below:

  • Set top boxes.
  • MP3 players.
  • DVD players.
  • Printers.
  • Antilock breaking systems.
  • USB devices like internet dongles.
  • Streaming players like Google Chromecast and Roku.
  • Thermostats.
  • Calculators.
  • Digital cameras.
  • ATM machines.
  • Video game consoles.
  • Routers and network peripherals.
  • Computer add-on cards and peripherals.
  • Digital watches.


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    • profile image

      shinde shubham ramesh 4 weeks ago

      very nice and superbbb information I like this information

    • profile image

      Agwu chioma 5 weeks ago

      WOW,thanks for the tips

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      Pratik raj 3 months ago

      Nice hub,well done that really worked for me, thanks

    • profile image

      Emmah 4 months ago

      Thenks for that

    • amuno profile image

      Alfred Amuno 8 months ago from Kampala

      Thanks for appreciating Ali

    • profile image

      ali hassan 8 months ago

      thanks this article is very nice

    • amuno profile image

      Alfred Amuno 22 months ago from Kampala

      Thanks Lizzie

    • profile image

      lizzie 22 months ago

      Awesome text

    • amuno profile image

      Alfred Amuno 3 years ago from Kampala

      Thanks Techpower.

    • Techpower profile image

      Techpower 3 years ago

      Nicely explained -Followed

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      bfilipek 3 years ago

      @amuno future seems to be quite near :) It would be great to predict the future and create some new device or app for new kind of devices.

    • amuno profile image

      Alfred Amuno 3 years ago from Kampala

      Thanks Thief for that.

    • Thief12 profile image

      Thief12 3 years ago from Puerto Rico

      Pretty good hub. Voted Up and Interesting.

    • amuno profile image

      Alfred Amuno 3 years ago from Kampala

      True bfilipek, wearable devices will be the next wave in computing. In as far as flexible devices are concerned, I bet we wait to see how realistic and flexible they actually get.

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      bfilipek 3 years ago

      good hub! I think that wearable devices will become more and more popular. Also the world is waiting for "flexible displays" and will also bring new kinds of devices.