History of Calculator,  Computing Systems and Computers From Ancient to 1950's

Term “Computers” was originally referred to people who did the thousands of calculations needed to produce the navigation and tide tables as well as astronomical almanacs needed by burgeoning sail born trade. The biggest problem then was that the calculations were very slow and inaccurate. As humans are the tool-making species, it’s natural that we worked for hundreds of years to find a way to mechanize math calculations.

Mechanical Computers

The abacus, invented in 300 B.C., really helped simple calculations such as addition and subtraction. The oldest abacus used pebbles in slots, where the five pebbles in the lower frame represented the fingers and two above represented two hands.

John Napier of Scotland invented logarithms in 1617. Logarithms allowed multiplication using addition. Each operand was looked up in a log table. The idea led directly to the slide rule which was invented in 1632 in England and used by engineers during the Apollo program.

Leonardo da Vinci came up with a design for a gear-driven computing machine. Blaise Pascal of France built the first gear-driven calculator, an adder to say precisely, in 1962. That primitive calculator always made mistakes as gears were not precise enough back then.

German mathematician Gottfried Leibniz built a multi-function calculator that could add, subtract, multiply, and divide in 1960. He even suggested the possible uses of binary numbers in calculating and invented the modern binary numbering system.

In 1801, Joseph Jacquard from France invented a powered loom that used wooden punch cards to automatically weave the detailed patterns including pictures and text, which was considered as the first “read only memory”. Certainly, it buried a foundation the computer punch card that became available many years later.

In 1830, the English mathematician Charles Babbage proposed a steam-driven calculating machine. That calculating machine had a size of a room. He named it “Difference Engine”. It could compute number tables, like logarithms or navigation tables. He got a big government funding for the project as the project had military and commercial significance. The project was never finished, so Babbage came up with an even bigger project called the Analytic Engine. It would have been powered by 6 steam engines and programmable with help of Jacquard’s punch cards. Babbage even proposed to use punched paper instead of wooden cards.

Babbage’ friend Ada Byron, daughter of famous poet Lord Byron, began “writing programs” for the un-built machine. The British government refused to get involved in this project, but Ada became the first computer programmer. She invented the subroutine and used “looping”, the re-use of a group of instructions. The computer programming language, computer Ada, was named after her.

Boolean Algebra

In 1847, a fellow started working on "symbolic logic". He felt that we could use mathematical reasoning to make some decisions. "If Suzy is off work AND I have $5 OR I can borrow it, we can go to the movies". Digital computers rely on the functions or operations of Boolean Algebra like AND, OR, XOR and NOT. George Boole hoped for the possibilities of human’s logical actions, just like what computers did a century later.

The next big thing actually came from America. Tabulating the US census results in 1880 took seven and a half years. It was predicted that results for the 1890 census might not be available before the 1900 census was taken if using the traditional tabulating technique. So Herman Hollerith invented a process using Jacquard's punched cards to do the work. A card reader sensed holes in the cards, a gear driven counter made from Pascal's idea kept results, and a wall full of dial indicators displayed the numbers. Hollerith established a company which eventually became IBM. IBM’s “Hollerith” cards became ubiquitous.

Electro-mechanical computers

IBM’s initial mechanical calculators could only add and subtract. Multiplication was done by repeated addition. After World War II began, the U.S. military needed a calculator capable of scientific calculations in order to make ballistic firing tables for big naval guns among other things. So Harvard and IBM built the Mark I computer in 1944 to do the job. That was a programmable mechanical-electrical digital computer through punched tape. That computer did not use binary arithmetic. It used switches, relays, rotating shafts, and clutches instead. It weighed 5 tons and measured 50 feet long. The Mark I computer could make addition or subtraction in three-tenths of a second, multiplication in four seconds, and division in ten seconds. The computer had nearly 750,000 components although it could store only 72 numbers.

Grace Hopper was a programmer on the Mark I. It was she who developed the first real computer language, COBOL, abbreviation for Common Business Oriented Language, in the early 1950s. She is also credited with having found the first actual computer bug, a dead moth blocking the paper tape reader, which made her the first debugger.

Since WWII began, Germany had used a class of electro-mechanical cipher machines, Enigma, to encode and decode shortwave radio transmissions. If the allies could decrypt the code they would know what instructions were sent to the Wermacht, the location to the Nazi U-Boatsn. By 1938 the Polish had developed an electro-mechanical device they called a bomb to speed comparison of thousands of possible solutions to the code used in a given message. They gave British intelligence a copy of an Enigma machine and a bomb in 1939. At the British code-breaking center Bletchley Park, Mathematician Alan Turing continued the development of much larger and more complicated bombs, which were now called “bombe”.

Another candidate for the grandfather of modern computers was the Colossus, also built by the British code breakers at Bletchley Park. Colossus was completed in 1944. Britain was the world leader in mechanical-electrical-electronic machines for code breaking. Colossus was a digital, partially electronic computer but it was certainly not a general purpose, programmable machine.

Electronic Computers

The father of the all-electronic digital computer ought to be ENIAC - Electronic Numerical Integrator and Calculator built by the University of Pennsylvania in 1943-45 by John Mauchly and J. Presper Eckert. Mauchly and Eckert promised the war department that they could replace all the women employed calculating the firing tables for the army's artillery guns.

ENIAC was huge, and it worked, although not before the end of the war. It filled a 20 by 40 foot room, weighed 30 tons, and used 17,468 vacuum tubes. It was silent, but hot with 150 kW of power. At the beginning it required about 8 hours of maintenance for every 8 hours of use. IBM paper card readers fed data into the computer that was reprogrammed by hundreds of patch cords and setting 3000 switches.

ENIAC could only hold 20 numbers at a time, but with a system clock of 2.8ms and no moving parts involved it was significantly faster than the Mark I - a multiplication operation only required 2.8 ms. ENIAC’s first task was computations in the development of the hydrogen bombs.

ENIAC was difficult to reprogram, requiring changes to all those patch cords and switches, which could take days even weeks. Eckert and Mauchly later teamed up with mathematician John von Neumann to design EDVAC, which perhaps was the first stored program computer. After ENIAC and EDVAC came ILLIAC, JOHNNIAC, and, not surprisingly MANIAC.

Importance of Transistors to Modern Computers

In 1947, IBM commissioned a study and concluded that six electronic digital computers would be sufficient to satisfy the computing needs of the entire United States. Unfortunately that conclusion was short sighted. There are six computers in an ordinary car today, all more powerful and much, much faster than the ENIAC.

Another important event took place in 1947 was that William Shockley and others at Bell Labs built the first transistor, which virtually changed everything. The British call electron tubes “valves” because a small electrical input voltage controls a much larger output current. Transistors are electronic valves too, but are much smaller and more reliable than tubes, consume much less power. Since the transistors became available, the development of computers had moved toward the integrated circuit, which consists of many transistors on a single piece of silicon. It was the integrated circuit that made a computer revolution possible.