Module One: The computer evolution (Notes)

The computer evolution is indeed an interesting topic that has been explained in some different ways over the years, by many authors. According to the Computational Science Education Project, US, the computer has evolved through the following stages: 

The Mechanical Era (1623-1945)

Trying to use machines to solve mathematical problems can be traced to the early 17th century. Wilhelm Schickhard, Blaise Pascal, and Gottfried Leibnitz were among 8 mathematicians who designed and implemented calculators that were capable of addition, subtraction, multiplication, and division included, The first multi-purpose or programmable computing device was probably Charles Babbage's Difference Engine, which was begun in 1823 but never completed.

The US Census Bureau was one of the first organizations to use the mechanical computers which used punch-card equipment designed by Herman Hollerith to tabulate data for the 1890 census. In 1911 Hollerith's company merged with a competitor to found the corporation which in 1924 became International Business Machines (IBM). 

First Generation Electronic Computers (1937-1953)

These devices used electronic switches, in the form of vacuum tubes, instead of electromechanical relays. The earliest attempt to build an electronic computer was by J. V. Atanasoff, a professor of physics and mathematics at Iowa 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 Pennsylvania. Research work began in 1943, funded by the Army Ordinance Department, which needed a way to compute ballistics during World War II. The machine was completed in 1945 and it was used extensively for calculations during the design of the hydrogen bomb. 

Eckert, Mauchly, and John von Neumann, a consultant to the ENIAC project, began work on a new machine before ENIAC was finished. The main contribution of EDVAC(Electronic Discrete Variable Automatic Computer), their new project, was the notion of a stored program. ENIAC was controlled by a set of external switches and dials; to change the program required physically altering the settings on these controls. EDVAC was able to run orders of magnitude faster than ENIAC and by storing instructions in the same medium as data. Eckert and Mauchly later designed what was arguably the first commercially successful computer, the UNIVAC; in 1952. Software technology during this period was very primitive. 

Second Generation (1954-1962)

The second generation witnessed several important developments at all levels of computer system design, ranging from the technology used to build the basic circuits to the programming languages used to write scientific applications. Electronic switches in this era were based on discrete diode and transistor technology with a switching time of approximately 0.3 microseconds. The first machines to be built with this technology include TRADIC at Bell Laboratories in 1954 and TX-0 at MIT's Lincoln Laboratory. Index registers were designed for controlling loops and floating point units for calculations based on real numbers 10

A number of high level programming languages were introduced and these include FORTRAN (1956), ALGOL (1958), and COBOL (1959). Important commercial machines of this era include the IBM 704 and its successors, the 709 and 7094. In the 1950s the first two supercomputers were designed specifically for numeric processing in scientific applications 

Third Generation (1963-1972)

Technology changes in this generation include the use of integrated circuits, or ICs (semiconductor devices with several transistors built into one physical component), semiconductor memories, microprogramming as a technique for efficiently designing complex processors and the introduction of operating systems and time-sharing.

Early in this third generation, Cambridge University and the University of London cooperated in the development of CPL (Combined Programming Language, 1963). CPL was, according to its authors, an 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 Computer Programming Language, 1967). 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. 

Fourth Generation (1972-1984)

Large scale integration (LSI - 1000 devices per chip) and very large scale integration (VLSI - 100,000 devices per chip) were used in the construction of the fourth generation computers. Whole processors could now fit onto a single chip, and for simple systems the entire computer (processor, main memory, and I/O controllers) could fit on one chip. Gate delays dropped to about 1ns per gate. Core memories were replaced by semiconductor memories.

In 1972, Dennis Ritchie developed the C language from the design of the CPL and Thompson's B. Thompson and Ritchie then used C to write a version of UNIX for the DEC PDP-11. Other developments in software include very high level languages such as FP (functional programming) and Prolog (programming in logic). IBM worked with Microsoft during the 1980s to start what we can really call PC (Personal Computer) life today. IBM PC was introduced in October 1981 and it worked with the operating system (software) called ‘Microsoft Disk Operating System (MS DOS) 1.0. Development of MS DOS began in October 1980 when IBM began searching the market for an operating system for the then proposed IBM PC and major contributors were Bill Gates, Paul Allen and Tim Paterson. In 1983, the Microsoft Windows was announced and this has witnessed several improvements and revision over the last twenty years. 

Fifth Generation (1984-1990)

This generation brought about the introduction of machines with hundreds of processors that could all be working on different parts of a single program. The scale of integration in semiconductors continued at a great pace and by 1990 it was possible to build chips with a million components - and semiconductor memories became standard on all computers. Computer networks and single-user work stations also became popular. Parallel processing started in this generation. Both wide area network (WAN) and local area network (LAN) technology developed rapidly. 

Sixth Generation (1990)

Most of the developments in computer systems since 1990 have not been fundamental changes but have been gradual improvements over established systems. This generation brought about gains in parallel computing in both the hardware and in improved understanding of how to develop algorithms to exploit parallel architectures. Workstation technology continued to improve, with processor. Wide area networks, network bandwidth and speed of operation and networking capabilities have kept developing tremendously.

Personal computers (PCs) now operate with Gigabit per second processors, multi-Gigabyte disks, hundreds of Mbytes of RAM, color printers, high-resolution graphic monitors, stereo sound cards and graphical user interfaces. Thousands of software (operating systems and application software) are existing today and Microsoft Inc. has been a major contributor. Microsoft is said to be one of the biggest companies ever, and its chairman – Bill Gates has been rated as the richest man for several years.