1. CLASSIFICATION OF DIGITAL COMPUTERS

2. INTRODUCTION
Computers are classified into different types based on the performance:
Microcomputers
Minicomputers
Mainframe Computers
Super Computers
Network Computers

3. MICROCOMPUTERS The most familiar type of computer.
It uses a microprocessor.
It is the least powerful among all.
In the past, microcomputers have been considered to be of two types – Personal computers and workstations.

4. Personal Computers (PCs)
PC’s are portable or desktop machines.
These systems could run simple applications like word processors, spreadsheets etc.
They were cheaper than workstations.
They had less processing power compared to Workstations
They had less sophisticated video display screens, operating systems and networking capabilities.
Example: Acer’s Aspire, Compaq Presario etc.

5. Personal Computers (PCs)

6. Workstations
These are powerful machines and more expensive until recently.
They were mainly used by engineers, scientists and other professionals who processed a lot of data.
People who used complex application programs and needed high quality graphics display screen used Workstations.
Workstations used display screens with high resolutions color graphics and operating systems that permitted multitasking.
They used a powerful processor.
They were also used for networking purposes.

7. WORKSTATIONS

8. Portable Computers
Personal computing market is seeing the miniaturization phenomena.
Now computers are becoming smaller and yet more powerful.
There are three categories of portable computers: laptops or notebooks PCs, Mini Notebooks and Personal Digital Assistant(PDA).

9. Portable Computers

10. Advantages of Portable Computers
Can be either AC-powered or battery-powered or both.
Useful for people who have to work away from their offices.
The user can be an executive, a student, a journalist, a salesperson etc.
These computers combine the power of a PC with mobility.
PDA’s combine Pen input, Writing recognition, personal organizational tools and communication capabilities in a very small package.

11. MINI COMPUTERS First released in the 1960's .
Mini computers got their name because of their small size compared to other computers of the day.
The capabilities of a minicomputer are some where between mainframes and personal computers.
Although some "minis" are designed for a single user, most are designed to handle multiple terminals.
The most powerful minicomputers can serve the input and output needs of hundreds of users at a time.

12. MINI COMPUTERS continued…..
Mini computers are commonly used as servers in the network environments that handle  the data sharing needs of other computers on the network .
Dozens or hundreds of personal computers can be connected to a network with a minicomputers acting as a server.
Like mainframes, midrange computers are used more and more as web servers, handling thousands of transactions per day. single - user mini computers are commonly applied to sophisticated design tasks, such as animation and video editing etc.
Mini computers cost  anywhere from $18000 to $500,000 and are ideal for many organizations and companies that cannot afford or do not need a mainframe system.

13. MINI COMPUTERS continued…..

14. MAINFRAME COMPUTERS
Mainframe computers can process several million instructions per second.
Large companies rely on large room-size systems to handle large programs with lots of data.
Mainframes are mainly used by insurance companies, banks, airline and railway reservation systems etc.
More powerful than MINICOMPUTERS.

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MAINFRAME COMPUTER
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16. SUPERCOMPUTERS Fastest calculating device ever invented.
A desktop PC operates on data and instructions in millionth of a second, where as a supercomputer can operate at speeds measured in nanoseconds or picoseconds – one thousand to one million times as fast as a micro computer.
Most supercomputers are used by government agencies.
Example of the uses of supercomputers are weather forecasting, oil exploration, weapons research, large-scale simulations etc.

17. SUPERCOMPUTERS
The main difference between a supercomputer and a mainframe computer is that, a supercomputer channels all its power into executing a few programs as fast as possible, where as a mainframe uses its power to execute many programs concurrently.
The Japan’s K-computer is the latest and the world’s powerful Supercomputer.
The speed is eight quadrillion instructions per second.

18. K - COMPUTER

21. NETWORK COMPUTERS
These are computers with minimal memory, disk storage and processor power, designed to connect to a network, especially internet.
The idea behind network computers is that many users who are connected to a network don’t need all the computing power from a typical computer system. Instead, they can rely on the power of the network server.
Network computers designed to connect to internet is sometimes called as Internet boxes, Net Pc’s.

22. REVIEW QUESTIONS
What are the different categories of digital computers?
Distinguish between the four kinds of computer systems.
How is a PC different from a workstation?
What are the different types of portable computers?
what is a PDA?
What are minicomputers?
What is the difference between a mini computer and a microcomputer?

23. REVIEW QUESTIONS
What is a mainframe computer and what are its typical applications?
What are supercomputers and where are they used?