Charles Babbage
(younger days)

Charles Babbage
(slightly older)

IBM 's Original Building

The first mechanical calculator ever built was constructed by Willhelm Schichard (1592-1633) in Tübingen, Germany, in 1623. Schichard made two copies both entirely in wood. The first one was made for the astronomer Kepler and the second one for himself. None of these machines exist today.

A similar, but far more famous calculator was built in 1642 by Blaise Pascal (1623 - 1662). This calculator could do simple calculations, such as addition and subtraction on six digit numbers. The rumour is that Pascal constructed the calculator for his father, who was a tax collector.

In the year 1671 Gottfried Leibniz (1646 - 1716) constructed a calculating machine. Not only did this machine include an addition unit, which was identical to Pascal's machine, but it also included an automatic multiplication and division unit. Leibniz's machine was therefore the first calculator which could handle the four rules of arithmetic. Like all other mechanical calculators before the 19th century, it became used only for academic interest.

Not until 1820 did Tomas of Comlar construct a mechanical calculator which became a commercial success.

Charles Babbage (1791 - 1871) is usually given credit for the mechanical computer but this is not entirely correct. He designed two computers during his lifetime; the 'Difference Engine' and the 'Analytical Engine'.

He began the construction of the Difference Engine in 1822, but he never concluded it. Furthermore, the Analytical Engine was thought out in 1834 yet only realized to some extent.

The purpose of the Difference Engine was to calculate mathematical tables and print them out automatically on paper. The current British government at that time, realized the importance of impeccable tables so they granted him 17.000 pounds for the development.

When completed, the Difference Engine was going to be able to calculate sixth grade polynomials with the precision of twenty digits. In 1842, after nineteen years of work, Babbage abandoned the project. One reason was probably that the precision of mechanics in that time was not accurate enough in order to clarify Babbage's demands.

It should be pointed out that a Swede, Georg Scheutz (1785 - 1873), with help from his son in 1843, after 16 years of work, completed a working Difference Engine. It could manage third grade polynomials and fifteen digit numbers. Three copies of the machine were produced and two of them were sold and shipped abroad. The first working computer in the world was accordingly Swedish, which is rarely noticed.

The Analytical Engine, which was Babbage's second machine, was more general than the Difference Engine. The machine was supposed to automatically perform all kinds of diffent mathematical operations.

Introducing the idea about a general machine, which was constructed without a specific purpose, was one of the most important contributions to computer science that Babbage made. Another contribution was the idea of a program that would control the general machine. The idea of changing the purpose of a machine simply be changing its program, was completely new at this time.

Unfortunately, Babbage's plans were too magnificent for that time. Therefore the Analytical Engine was only partially built during Babbage's lifetime. However, it is uncertain if a mechanical machine with this capacity could have ever been constructed.

Enter Electronics

The greatest disadvantage of mechanical calculators was their calculating speed which was limited by the moving parts. Furthermore their memory was much too complex to be reliable.

In 1906 Lee de Forest (1873 - 1961) invented the Electron tube, a component which is not only used in calculations but is also suitable for binary storage of numbers. The electron tube is the foundation of the first generation of electronic computers and which improved their speed compared to the mechanical generation.

The dawn of modern computers

In the late 1930's, about 30 years after de Forest's invention of the electron tube, Joh V Atanasoff (born in 1903) tried to build the first electronic computer at Iowa State University. It was called the ABG computer. The machine was never completed but it played an importand part in the birth of ENIAC.

ENIAC, which stands for Electronic Numerical Integrator And Calculator, is the computer that John W Mauchly (1907 - 1980) and J Presper Echert built for the US Army. They built it together at the Moore School between the years 1943 and 1946.

ENIAC became a large construction. Its weight was about 30 tons and it was almost 30 meters long. Furthermore the machine consisted of about 18.000 electron tubes and 500.00 solderings. The purpose of ENIAC was the same as Babbage's machines, which was to calculate tables. In ENIAC's case these tables were for balistic missiles.

The two biggest limitations of ENIAC were the limited memory and the complicated programming; the greatest one being, of course, the programming. ENIAC's first program consisted of one million punchcards, which did calcultations for the hydrogen bomb.

To solve these problems Mauchly and Echert contact the Hungarian mathematician, John von Neumann (1903 - 1957). Von Neumann worked out how a program could be electronically stored in the computer's memory and be represented in numbers. Von Neumann also introduced binary representation of numbers.

Another mystical computer pioneer who deserves a mention was the Briton, Alan Turing (1912 - 1954). After brilliant studies in mathematics, logic and computer science, Turing wrote several ground-breaking reports about the so-called Turing Machine, which was a simple theoretic computer.

Once he had turned down the job as von Neumann's assistant, Turing served at the State Code and Cryptography school in Bletchley Park during the Second World War. With a whole staff of code-breakers, Turing succeeded in cracking several German codes. Alan Turing died in 1954 under mysterious circumstances. However, it is now commonly accepted that he was severly depressed by medicine which was supposed to cure him from his homosexuality and committed suicide by eating an apple covered with cyanide.

THE NEXT STEP FORWARDS

The second generation of computers stretches between the years 1955 and 1964. The most distinctive sign is the transition from electron tubes to transistors. The transistor was invented by Schockley, Bardeen and Brattain in 1948 at AT&T Bell Labs which later gave them the Nobel Prize in physics.

Now people started to talk about computer systems and high level languages like FORTRAN (FORmula TRANslation, 1954) and COBOL (COmmon Business Oriented Language, 1959) were developed. Some typical examples of second generation computer systems are IBM 7090 AND IBM 7094, which both became major commercial successes.

After gaining greater performance through improvements in technology, the search for system improvements and completely new alternative architechtures began.

Von Neumann laid the theoretical foundation for the design on an array-processor, which is a special kind of processor that is used in some parallel computer systems.

Stage Three - Enter the Heavyweights

The boundary towards the third generation of computer is not completely clear but it is usually distinguished by the use of integrated circuits - IC. These circuits superceded transistors and magnetic memories. The breakthrough for the so-called micro programming is another sign of the third generation.

There were a great number of third generation computers but IBM's System/360 was one of the most popular computer systems of that time. At the time of its launch in 1965, its makers - Amdahl, Blaauw and Brook, minted the term "computer-architecture"

In 1964, Control Data Corporation (CDC), delivered the first Super Computer, DCD 6600. Thornton and Cray were the heavy names behind it. The CDC machines were significantly faster than the IBM 360 family therefore IBM lost the larger part of the Super Computer market to Control Data Corporation.

Step Four - The Incredible Shrinking Hardware

The Transition to the fourth generation of computers was in the first half of the 70's which was emphasized by the breakthrough of the micro-processor and the increased number of developed parallel architectures. Both occurrences were completely dependent on the new compact IC circuit.

The first commercial micro-processor, I4004, was introduced in 1971 by the Intel Corporation.

Three years later Motorola introduced their 6800 processor.

In 1972, Seymour Cray left Control Data Corporation and started his own company, Cray Research Inc. To many, this resulted in Cray-1 becoming synonymous with Super Computer.

Due to a short developing time of about four years, and a very late selection of components, Cray could get the latest technology available. Consequently he could deliver a very fast computer to the market. This is one main reason for its success.

What was the next step?

Some people are of the opinion that we have not reached the fifth generation of computers yet, since there has not been any large steps in technology or architecture. Furthermore, it is difficult to know if new trends will be a future technology or just a sidetrack.

Conclusion

There is a continuous development of both technology and architecture, which makes new things possible. Technology from yesterday's Super Computers is adjusted and squeezed, with newer and more compact circuit technologies, into today's micro-processors. Massive parallelism with thousands of simple processors and special networks are explored. New compilers and operating systems for parallel systems are developed which makes it easier for the programmer to develop programs for new architectures etc.