Generation of Computer

Generation of computer

Introduction

The development of electronic computers had clearly helped to visualize the concept of computer.  The computer system has taken a big leaf forward with each technological breakthrough during the development process. The functions performed and speed of computer in continuously changing. There is great variations in size and cost and great breakthrough in hardware and software which result more and more advance computer. In depth, there are altogether six major stages in the continuous development process of the computer. These stages are called generations of computers.

1. First Generation Computers (1937-1953)

The computers developed during 1937 to 1953 are known as first generation computer. This generation is characterized by vacuum tube. Vacuum tube is electronic component for their hardware component. The size of this generation computer was very high. Following are the important features of first generation computers.

- Vacuum tubes were used for electronic and magnetic drums which were used for primary storage medium.

- Storage capacity was limited (e.g. 1 Kilobytes to 4 Kilobytes)

- The operating speed was slow. (e.g. in millisecond)

-  Large in size.

- This generation computer use low level language or machine level language.

- These computers were used for scientific calculations and record keeping.

- They produce more heat during operation.

- These computers need more electricity to work.

Three machines have been promoted at various times as the first electronic computers. These machines used electronic switches, in the form of vacuum tubes, instead of electromechanical relays. In principle the electronic switches would be more reliable, since they would have no moving parts that would wear out, but the technology was still new at that time and the tubes were comparable to relays in reliability. Electronic components had one major benefit, however: they could "open" and "close" about 1,000 times faster than mechanical switches.

The earliest attempt to build an electronic computer was by J.V. Atanasoff, a professor of physics and mathematics at Lowa state in 1937. Atanasoff set out to build a machine that would help his graduate students solve systems of partial differential equations. By 1941 he and graduate student Clifford Berry had succeeded in building a machine that could solve 29 simultaneous equations with 29 unknowns. However, the machine was not programmable, and was more of an electronic calculator.

The first general purpose programmable electronic computer was the Electronic Numerical Integrator and Computer (ENIAC), built by J. Presper Eckert and John V. Mauchly at the University of Pennsylvnia. Another new concept developed was EDVAC (Electronic Discrete Variable Automatic Computer). The main contribution of EDVAC was, the notion of stored program. EDVAC was able to run orders of magnitude faster than ENIAC. By storing instructions in the same medium as data, designers could concentrate on improving the internal structure of the machine without worrying about matching it to the speed of an external control.

Software technology during this period was very primitive. The first programs were written out in machine code, i.e. programmers directly wrote down the numbers that corresponded to the instructions they wanted to store in memory. By the 1950s programmers were using a symbolic notation, known as assembly language, then hand. Translation the symbolic notation into machine code. Later programs known as assemblers performed the translation task.

2. Second Generation (1954-1962)

In 1948-1949, scientists invented another electronic component called transistor which was used instead of vacuum tube in first generation computers. The compute using transistor as storage media are classified as Second Generation Computers. One transistor could do task.

The second generation saw several important developments at all levels of computer system design, from the technology used to build the basic circuits to the programming languages used to write scientific applications. Important innovations in computer architecture include index register for controlling loops and floating point units for calculations based on real numbers.

During this generation many high level programming languages were introduced, including FORTRAN (Formula Translation) in 1956, ALGOL (Algorithm Language) in 1958, and COBOL (Common Business Oriented Language) in 1959. Important commercial machines of this era include the IBM 704 and its successors, the 709 and 7049. The later introduced I/O processors for better throughput between I/O devices and main memory.

The second generation also saw the first two supercomputers designed specifically for numeric processing in scientific applications. The term "supercomputer" is generally reserved for a machine that is an order of magnitude more powerful than other machines of its era. Two machines of the 1950s deserve this title. The Livermore Atomic Research Computer (LARC) and the IBM 7030 (aka Stretch) were early examples of machines that overlapped memory operations with processor operations and had primitive form of parallel processing.

3. Third Generation (1963-1972)

The third generation brought huge gains in computational power. Innovations in this era include the use of integrated circuits, or ICs (semiconductor devices with several transistors built into one physical component), semiconductor memories starting to be used instead of magnetic cores, microprogramming as a technique for efficiently designing complex processors, the coming of age of pipelining and other forms of parallel processing and the introduction of operating systems and time-sharing.

The first ICs were based on small-scale integrations (SSI) circuits, which had around 10 device per circuit (or "chip"), and evolved to the used of medium-scale integrated  (MSI) circuits, which had up to 100 devices per chip. Multilayered printed circuits were developed and core memory was replaced by faster, solid state memories.

This generation computer can perform parallel processing perfectly which cause fast processing in computer system. In parallel processing, more than one process can be performed at same time. Another important feature of this generation computer was multiprocessing and multiprogramming where multiprocessing means more than one process can be process can be performed at same time by same processor where as multiprogramming means more than one programming can run at same time by same processor.

In this third generation, Cambridge and the University of London cooperated in the development of CPL (Combined Programming Language, 1963). CPL was, according to its authors, and attempt to capture only the important features of the complicated and sophisticated ALGOL. However, like ALGOL, CPL was large with many features that were hard to learn. In an attempt at further simplification, Martin Richards of Cambridge developed a subset of CPL called BCPL (Basic Combined Programming Language) in1967. In 1970 Ken Thompson of Bell Labs Developed yet another simplification of CPL called simply B, in connection with an early implementation of the UNIX operating system.

4. Fourth Generation (1972-1984)

The next generation of computer systems saw the use of large scale integration (LSI) 1000 devices per chip and very large scale integration (VLSI - 100,000 devices per chip) in the construction of computing elements. At this scale entire processors will fit onto a single chip, and for simple systems the entire computer (processor, main memory and I/O controllers) can fit on one chip. Gate delays dropped to about 1 ns (nanosecond) per gate.

During this generation computer microprocessor was developed. Microprocessor is that type of chip where AL, Control Unit and Main memory and related small memories are integrated inside single chip.

Semiconductor memories replaced core memories as the main memory in most systems; unit this time the use of semiconductor memory in most systems was limited to register and cache. During this period high speed vector processors, such as the CRAY1, CRAY X-MP and CYBER 205 dominated the high performance computing scene. Computers with large main memory, such as the CRAY 2, began to emerge. A variety of parallel architectures began to appear; however, during this period the parallel computing efforts were of a mostly experimental nature and most computational science was carried out on vector processors microcomputers and workstations were introduced and saw wide use as alternatives to time shared mainframe computers.

Developments in software include very high level languages such as FP (Functional Programming) and Prolog (Programming in logic). These languages tend to use a declarative programming style as opposed to the imperative style of Pascal, C, FORTRAN, etc. two important events marked the early part of the third generation: the development of the C programming language and the UNIX operating system, both at Bell Labs. In 1972, Dennis Ritchie, seeking to meet the design goals of CPL and generalize Thompson's B, developed the C language. Thompson and Ritchie then used C to write a version of UNIX for the DEC-11.

5. Fifth Generation (1984-1990)

The development of the next generation of computer systems is characterized mainly by the acceptance of parallel processing. Until this time parallelism was limited to pipelining and vector processing, or at most to a few processors sharing jobs. The fifth generation saw the introduction of machines with hundreds of processors that could all be working o different parts of a single program. The scale of integration in semiconductors are continued at an incredible pace - by 1990 it was possible to build chips with a million components and semiconductor memories became standard on all computers.

Other new developments were the widespread use of computer networks and the increasing use of single-user workstations. Prior to1985 large scale parallel processing was viewed as a research goal, but two systems introduced around this time are typical of the first commercial products to be based on parallel processing.

Computer network is another new concept used in this generation computer. Computer network means connection of computer with each other to exchange information and to share the resources.

Intel connected each processor to its own memory and used a network interface to connect processors. This distributed memory architecture meant memory was no longer a large systems (using more processors) could be built. Toward the end of this period a third type of parallel processor was introduced to the market. In this style of machine, known as data-parallel or SIMD, there are several thousand very simple processors. All processors work under the direction of a single control unit; i.e. if the control unit says 'add a to b" then all processors find their local copy of a and add it to their local copy of b.

Scientific computing in this period was still dominated by vector processing. Most manufactures of vector processors introduced parallel models, but there were very few (two to eight) processors in this parallel machine. In the area of computer networking, both Wide Area Network (WAN), Local Area Network (LAN) technology developed at a rapid pace, stimulating a transition from the traditional mainframe computing environment toward a distributed computing environment in which each user has their own workstation for relatively simple tasks (editing and compiling programs, reading mail) but sharing large, expensive resources such as file servers and supercomputers. RISC (Reduced Instruction Set Computer) technology ( a style of internal organization of the CPU) and plummeting costs for RAM brought tremendous gains in computational power of relatively low cost workstations and servers. This period also saw a market increase in both the quality and quantity of scientific visualization.

6. Sixth Generation (1990-)

Transitions between generations in computer technology are hard to define, especially as they are taking place. Some changes, such as the switch from vacuum tubes to transistors, are immediately apparent as fundamental changes. But others are clear only in retrospect. Many of the developments in computer systems since 1990 reflect gradual improvements over established systems, and thus it is hard to claim they represent a transition to a new "generation", but other developments will prove to be significant changes.

This generation is beginning with many gains in parallel computing, both in the hardware area and in improved understanding of how to develop algorithms to exploit diverse, massively parallel architectures. Parallel systems now complete with vector processors in terms of total computing power and most expect parallel systems to dominate the future.

Workstation technology has continued to improve, with processor designs now using a combination of RISC, pipelining, and parallel processors. As a result it is now possible to purchase a desktop workstation for about $30,000 that has the same overall computing power (100 megaflops) as fourth generation supercomputers. This development has sparked an interest in heterogeneous computing: a program started on one workstation can fine idle workstations elsewhere in the local network to run parallel subtasks.

The expected features of computers are natural language processing, artificial intelligence, problem solving techniques, pattern recognition and speech recognition.