Classification of Computer | Computer Science Notes Grade 11

In this session here we are trying to make computer science notes grade 11 on Classification of Computer topic, in this topic we are include classification of computer on the basis of size and working principle. this notes is only educational purpose not any commercial uses.

On the basis of Size – Super, Mainframe, Mini and Micro Computers.

1. Super Computer:

The super computer is the most powerful and fastest computer among digital computers. This computer is special purpose and is capable of handling huge amounts of calculations that are beyond human capabilities. It can perform at billions of instruction per second (BIPS) and more. Some of today’s super computer has the computing capability equal to that of 40,000 micro-computers. This computer is the most expensive computer (cost around 15-20 million-dollar range). Due to it’s high cost and size, it is relatively rare. It used only by large corporations, universities, and government agencies mainly in the areas of defense and weaponry, weather forecasting, scientific research, satellite communication etc. Example: CRAY X-MP/24, NEC-500 PARAM, ANURAG etc.

Classification of Computer | Computer Science Notes Grade 11

2. Mainframe Computer:

A mainframe computer is a large computer with hundreds of processors. It can process a larger amount of smaller tasks quickly. A mainframe computer is smaller than a supercomputer. The supercomputer is the larger and fastest computer ever made.

Mainframe computers have the size of a refrigerator. Before 2000, these computers were big in size covering the whole room. But now these computers have decreased in size and improve in performance. It occupies very largely with an approximate area of 1000 sq. ft. it supports a large number of I/O terminals, more than 100 terminals.

Mainframe Computer, Classification of Computer | Computer Science Notes Grade 11

Advantages of mainframe computer

High-end scalability: They are scalable in the sense that more hardware i.e. processors and memory can be added if needed. In mainframe computer, more than 600 processors are directly managed by the operating system while many other processors are connected whose work is to move data within the mainframe computer.

Security: The security of these computers is very high. As these computers are used in banks so the security is very important. In banks, these computers are used for managing online transactions, processing of credit and debit cards.

Long-lasting performance: These computers have a minimum time limit of 10 years. So they can perform well for 10 years and after that period companies can upgrade the mainframe computer or replace it.

Continuing compatibility: Mainframe computers have their own operating system e.g. IBM have their own operating system that can manage these computers. These computers are highly compatible with the processors and other hardware and software.

Huge memory storage: Due to a high number of processors these computers have huge memory that can store and process large amount data at a time.

Virtualization: These systems have a logical partition which can help mainframe to overcome memory limitation.

Can run multiple OS: In mainframe computer, more than one operating system can be run at a time to boost the performance of the system.

Real-time monitoring and control: If any fault comes in the system then the administrator of the system is notified instantly. Suppose there is hardware failure then that hardware should be replaced to resume the work.

Disadvantages of mainframe computer

High cost: These computers have a very high price and they cannot be used in homes. Mainframes are only used by big organization, banks, large websites and government agencies.

Hardware/software is expensive: Windows and mac are not run on mainframe computers. These computers have custom software and hardware that are expensive for the normal user.

A lot of space required: Mainframe computers need a large space and also the temperature of the place should not be hot.

High technical staff: For maintaining mainframe computer specialized staff is needed. A normal computer user cannot operate and debug the system.

Command drove interface: The terminal connected to the mainframe computer have the text and a command-based interface that is difficult to understand.

Hardware crash: If any hardware crashed then the whole system stops working.

Examples of mainframe computer

  • IBM Z-series
  • BIM 1401
  • System z10 servers
  • HP mainframe

Mainframe Features

In this Mainframe tutorial, you will learn about features of Mainframe – Processing power, memory capacity, performance, computing, multiple operating system, time sharing, reliability, serviceability, availability, clustering technology and other features available in Mainframe.

Large Number of CPU with Greatest Processing Power:

The mainframe has greatest processing capacity and to support this there is large number of CPU’s with high processing power embedded within the frame.

Huge Memory Capacity:

As explained before the mainframe applications takes its presence in large scale operations and to support this facility the memory capacity embedded within mainframe is very huge, in some cases it could even be about more than 8 Gigabyte.

Increased Performance by Sharing workload:

Mainframes systems have the ability to share the workload among different processors and input and output devices. This makes its processing ability and power to be efficient and increases its performance.

Centralized Computing:

The mainframe system handles centralized computing by which all the operations takes place in the processor section of mainframe and the results are seen in the desktop monitor with the help of a utility or program running on the mainframe background.

Ability to Run in Multiple Operating System:

Mainframes have the ability to run multiple operating systems and by this feature it is possible to function mainframe systems not as a single computer but as a number of virtual machines.

Supports Time Sharing Ability:

By the feature of Time Sharing Ability supported by mainframes it is possible for thousands of users to operate and use the machine simultaneously with efficiency.

Supports Sophisticated Operating system:

Mainframe system supports sophisticated operating systems like UNIX, Linux and VMS and IBM operating systems like Z/OS, Z/VM, and VSE/ESA.


The main important feature of mainframe system was its Reliability which made its usage wide spread among commercial customers. Mainframe systems are Reliable systems which gives high performance, which is essential for reasonable operations against a database.


As we have seen the mainframe system and application takes its presence in critical and complex business applications which requires the system to be available at all times with 100% throughput. This is completely achievable and provided by mainframe system and it’s really impossible to hear any system outage for any reasons in a mainframe system making its availability for applications throughout. The above is achieved by mainframe system by its great design where Memory chips, memory busses, I/O channels and power supplies are provided with a pair more, ensuring the system availability throughout.


It is possible to replace most of the components in the mainframe system with the system operating concurrently. Certain components like CPU if needed to be replaced of course requires the system operation to be shut down in which case this is done during the scheduled outage as per the users convenience.

Note: IBM 1401 was the first computer brought to Nepal

3. Mini Computer:

First released in the 1960s, minicomputer got its name because of its smaller size and cost compared to a mainframe computer. The capabilities of a minicomputer are somewhere between mainframe and microcomputer. For this reason, a minicomputer is often called a midrange computer. It is a work group computer system, a smaller but powerful multiuser system computer with excellent memories and processing speed. Like mainframe, minicomputer can handle much more input and output than a microcomputer. It can support about 50 terminals and requires an area of around 100 sq ft. users can access a central minicomputer through a terminal or a standard PC. Example: Prime 9755, VAX 7500, HP3000 series etc.

Mini Computer, Classification of Computer | Computer Science Notes Grade 11

4. Micro Computer:

A computer, which is based on a microprocessor is called a microcomputer. It is a small, low cost digital compute. It requires small space, can be placed on a table, or even kept inside a briefcase. This computer has a central processing unit on a single chip. It is mainly used in office, house, school, shop, and store. The smallest of this category are laptop, notebook, palmtop, and PAD. Example: IBM PC, Apple/ Macintosh.

Micro Computer, Classification of Computer | Computer Science Notes Grade 11

On the basis of Working Principle (Function) – Analog, Digital and Hybrid computers.

1. Analog Computer:

 It works on continuous data. It is used to measure natural or physical values.
 It is specific to a particular task. It is not versatile.
 Accuracy of analog computer is not so high in comparison to digital computer.
 Generally analog computer does not have storage capacity as it works on real time basis
 It also gives the output in the form of curve line or graph so it may not be meaningful to all.

2. Digital Computer:

 Digital computer operates by counting rather than measuring.
 Digital computer is based on digital signal.
 They are the general purpose computer.
 They have storage capacity. They can store data internally or in external device also.
 These computers are programmable and can be used for multipurpose.
 The accuracy of digital computer is very high.
 It has faster processing speed.

3. Hybrid Computer:

Hybrid means the production of something by mixing two or more different components. Hybrid computer is also the combination of two distinct analog computer and digital computers. Generally, hybrid computer used in Aeroplan, Industries, Hospital etc.
 It works on continuous as well as discrete value.
 It also specific to a particular work and not versatile machine.
 It converts the analog values to digital values and vice-versa.
 It is not easily reprogrammable computer.
 It is very high cost.
 The examples: CT scan, Ultra Sonogram etc.

check here to find more notes

source: local books;

Leave a Reply

Your email address will not be published.

error: Content is protected !!