Minicomputer

A minicomputer (colloquially, mini) is a class of multi-user computers that lies in the middle range of the computing spectrum, in between the largest multi-user systems (mainframe computers) and the smallest single-user systems (microcomputers or personal computers). The class at one time formed a distinct group with its own hardware and operating systems, but the contemporary term for this class of system is midrange computer, such as the higher-end SPARC, POWER and Itanium -based systems from Sun Microsystems, IBM and Hewlett-Packard.

It is a midsize computer. A minicomputer is a multi-processing system capable of supporting from up to 250 users simultaneously.

The term "minicomputer"evolved in the 1960s to describe the smaller computers that became possible with the use of transistors and core memory technologies, minimal instructions sets and less expensive peripherals such as the ubiquitous Teletype Model 33 ASR. They usually took up one or a few 19-inch rack cabinets, compared with the large mainframes that could fill a room.

WorkStation

A workstation is a high-end microcomputer designed for technical or scientific applications. Intended primarily to be used by one person at a time, they are commonly connected to a local area network and run multi-user operating systems. The term workstation has also been used to refer to a mainframe computer terminal or a PC connected to a network.

Both being microcomputers, workstations had offered higher performance than desktop computers, especially with respect to CPU and graphics, memory capacity, and multitasking capability. They are optimized for the visualization and manipulation of different types of complex data such as 3D mechanical design, engineering simulation (e.g. computational fluid dynamics), animation and rendering of images, and mathematical plots. Typically, consoles consist of a high resolution display, a keyboard and a mouse at a minimum, but also offer multiple displays, graphics tablets, 3D mice (devices for manipulating 3D objects and navigating scenes), etc.

PC (Personal Computer)

Personal computers are now a very common item in many houses yet in 1955, there were only 250 computers in use throughout the world. In 1980, more than one million personal computers had been sold and by the mid-1980’s, this figure had risen to 30 million. How did this come about? 

A computer in 1955 was very large and could not have fitted into a normal room in a normal sized house. They frequently burned out and had a tendency to attract moths into the system which short-circuited them. (Getting a computer ‘bug’ now refers back to the time when moths were a problem to the early computers).

Types of Computer

Computer can be broadly classified by their speed and computing power.

Sl. No.	Type	Specifications
1	PC (Personal Computer)	Single user computer system. Moderately powerful microprocessor.
2	Work Station	Single user computer system. Similar to Personal Computer but have more powerful microprocessor.
3	Mini Computer	Multi-user computer system. Capable of supporting hundreds of users simultaneously.
4	Main Frame	Multi-user computer system. Capable of supporting hundreds of users simultaneously. Software technology is different from minicomputer.
5	Supercomputer	An extremely fast computer which can perform hundreds of millions of instructions per second.

Fifth Generation (The period of Fifth Generation is 1980-till date)

In the fifth generation, the VLSI technology became ULSI (Ultra Large Scale Integration) technology, resulting in the production of microprocessor chips having ten million electronic components. This generation is based on parallel processing hardware and AI (Artificial Intelligence) software. AI is an emerging branch in computer science, which interprets means and method of making computers think like human beings. All the Higher level languages like C and C++, Java, .Net etc. are used in this generation.

Fourth Generation (Period of Fourth Generation was 1971-1980)

The fourth generation of computers is marked by the use of Very Large Scale Integrated (VLSI) circuits.VLSI circuits having about 5000 transistors and other circuit elements and their associated circuits on a single chip made it possible to have microcomputers of fourth generation. Fourth Generation computers became more powerful, compact, reliable, and affordable. As a result, it gave rise to personal computer (PC) revolution.

Third Generation (The period of third generation was 1965-1971)

The third generation of computer is marked by the use of Integrated Circuits (IC's) in place of transistors.A single I.C has many transistors, resistors and capacitors along with the associated circuitry.The I.C was invented by Jack Kilby. This development made computers smaller in size, reliable and efficient.

Second Generation (The period of second generation was 1959-1965)

This generation using the transistor were cheaper, consumed less power, more compact in size, more reliable and faster than the first generation machines made of vaccum tubes.In this generation, magnetic cores were used as primary memory and magnetic tape and magnetic disks as secondary storage devices.
In this generation assembly language and high level programming language like FORTRAN, COBOL were used.
There were Batch processing and Multiprogramming Operating system used.

First Generation (The period of first generation : 1946-1959. Vaccum tube based.)

The period of first generation was 1946-1959.

First generation of computer started with using vacuum tubes as the basic components for memory and circuitry for CPU(Central Processing Unit). These tubes like electric bulbs produced a lot of heat and were prone to frequent fusing of the installations, therefore, were very expensive and could be afforded only by very large organisations.

Modern Computers Defined

Modern computers are electronic and digital. The actual machinery -- wires, transistors, and circuits -- is called hardware; the instructions and data are called software.

All general-purpose computers require the following hardware components:

1. Memory: enables a computer to store, at least temporarily, data and programs. 
2. Mass Storage Device: allows a computer to permanently retain large amounts of data. Common mass storage devices include disk drives and tape drives. 
3. Input Device: usually a keyboard and mouse, the input device is the conduit through which data and instructions enter a computer. 
4. Output Device: a display screen, printer, or other device that lets you see what the computer has accomplished. 
5. Central Processing Unit (CPU): the heart of the computer, this is the component that actually executes instructions.

The History of Computers

"Who invented the computer?" is not a question with a simple answer. The real answer is that many inventors contributed to the history of computers and that a computer is a complex piece of machinery made up of many parts, each of which can be considered a separate invention.

This series covers many of the major milestones in computer history (but not all of them) with a concentration on the history of personal home computers.

The computer as we know it today had its beginning with a 19th century English mathematics professor name Charles Babbage. He designed the Analytical Engine and it was this design that the basic framework of the computers of today are based on. Generally speaking, computers can be classified into three generations. Each generation lasted for a certain period of time,and each gave us either a new and improved computer or an improvement to the existing computer.

What is a Computer?

A computer is a programmable machine. The two principal characteristics of a computer are: it responds to a specific set of instructions in a well-defined manner and it can execute a prerecorded list of instructions (a program). Computer is a general purpose device that can be programmed to carry out a finite set of arithmetic or logical operations. Since a sequence of operations can be readily changed, the computer can solve more than one kind of problem.