The Era of Mechanical Computing: When Computers were Bigger than a Room

The Babbage Engine

During the time when Boole was defining Boolean logic, Charles Babbage was developing his 'analytical engine', the muse for today's computer. Charles Babbage (1791-1871) designed the first automatic computing engines but failed to build them. The first complete Babbage Engine was finished in London in 2002, 153 years after it was designed.

Babbage had designed two types of engine, Difference Engine, and Analytical Engine. Difference engine is so called because of the mathematical principle on which they are based, namely, the method of finite differences, which uses only arithmetical addition and removes multiplication and division that are more difficult to implement mechanically. Difference engine is largely a calculator. It crunches numbers by repetitive addition according to the method of finite differences. They cannot be used for general arithmetical calculations.­

Analytical Engine is much more than a calculator and marks the progression from the mechanized arithmetic of calculation to full-fledged general-purpose computation. Despite its importance, analytical engine was never completed. It failed due to lack of precision machining techniques at the time. It is also believed that Babbage was working on a solution that was much ahead of its time and so no one could understand its importance. After him, there was a temporary loss of interest in automatic digital computers.

Lady Augusta Ada

Augusta Ada King, countess of Lovelace, was an English mathematician often credited as the first computer programmer for her writings about Charles Babbage's Analytical Engine. Her notes were republished in 1953, as the only description or explanation of the Babbage engine and the software to use it.

Her notes were labelled alphabetically from A to G. In note G, the Countess describes an algorithm for the analytical engine to compute Bernoulli numbers. This algorithm is considered the first ever algorithm to be implemented on a computer, and for this reason she is often cited as the first computer programmer. To her great disappointment, the engine was never actually constructed to completion during Lovelace's lifetime.

Herman Hollerith- Census Tabulating machine

In 1881, Herman Hollerith, widely regarded as the father of modern automatic computation, began working on a machine to tabulate census data. With the traditional method the 1880 census had taken eight years to complete. He invented punched cards that used electricity to read, count, and sort punched cards with holes representing data gathered by the census-takers. The census data was coded onto cards using a keypunch. Then these cards were taken to a tabulator for counting and tallying to be arranged alphabetically. His invention was used for the 1890 census that was completed in only a year by the US Census Bureau.

Hollerith, realising the potential of tabulating and sorting machines, left the U.S. Census Bureau in 1896 to found the Computer Tabulating Recording Company. His punch-card machines became national bestsellers and in 1924 it became part of IBM. The punched card formed the basis for storing and processing information. He did not stop at his original 1890 tabulating machine and sorter, but produced many other innovative new models. He also invented the first automatic card-feed mechanism, the first key punch, and took what was perhaps the first step towards programming by introducing a wiring panel in his 1906 Type I Tabulator.

Hollerith's designs dominated the computing landscape for almost 100 years. Punch card technology was used in computers up until the late 1970s. In computers they were read electronically, moving between brass rods, with the holes in the cards, creating an electric current where the rods would touch.

Vacuum Tube

A vacuum tube is basically a glass tube surrounding a vacuum with electrical contacts on the ends for flowing current through it. Thomas Edison noticed this first in 1883, when he was working on lightbulbs. He found that electric current doesn't need a wire to move through. It can travel right through a gas or even a vacuum. Popularly known as Edison effect, this theory was a precursor to the invention of transistor. Edison's discovery that current can travel through a vacuum didn't turn out to be very useful information until 1904, when British scientist John A. Fleming made a vacuum tube known as valve, now called diode. This valve forced current in the tube to travel exclusively in one direction, an attribute considered critical for radio sets which needed to turn alternating current into direct current.

However, the full-blown invention of Vacuum tube is attributed to American physicst Lee Dee Forest, who, in 1946 not only made force current to move in a single direction, but also increase the current along the way. De Forest put a metal grid in the middle of the vacuum tube. By using a small input current to change the voltage on the grid, De Forest could control the flow of a second, more powerful current, through the tube. Vacuum tube played an important role in the development of electronic technology that led to the expansion and commercialization of radio broadcasting, television, radar, large telephone networks, and eventually analog and digital computers.

Harvard Mark- IBM ASCC

In 1931 the U.S. Navy and IBM teamed up to build an all-purpose computer that could be used to calculate logistics in case of a large scale battle. The Second World War provide the perfect stage for its deployment. The computer, called Mark 1, was completed in 1944 and was the first computer to use the base-2 binary system, was programmable, and made of vacuum tubes, relays, magnets, and gears. The Mark 1 had a memory for 72 numbers and could perform 23-digit multiplication in 4 seconds. It was operational for 15 years and performed many calculations for the U.S. Navy during Second World War.

The Mark I was followed by the Harvard Mark II in 1948, Mark III in 1949, and Mark IV in 1952. Mark III was the first in the series that used mostly electronic components, using vacuum tubes and crystal diodes. But, it was Mark IV that was all-electronic, using solid state components, besides having magnetic drum memory. Mark computers were reliable, much more so than early electronic computers, and have been called as "the beginning of the era of the modern computer"

ABC computers- Atanasoff Berry Computer

ABC or the Atanasoff—Berry Computer was the first electronic digital computing device that was not programmable and could only solve systems of linear equations. It was invented by Atanasoff in collaboration with Clifford Berry in 1937 and was successfully tested in 1942. ABC was 1,000 times more accurate than the then-reigning Vannevar Bush differential analyser which did calculus by rotating gears and shafts, whereas, ABC worked on a binary system, working in logic rather than enumeration, operating predominantly by means of electron devices such as vacuum tubes; later with transistors and now, microchips.

ABC easily ran systems with up to twenty-nine equations, a tough task then. The machine could be fed two linear equations with up to twenty-nine variables and a constant term and eliminate one of the variables. This process would be repeated manually for each of the equations, which would result in a system of equations with one fewer variable. Then the whole process would be repeated to eliminate another variable. The later genres of computers were considered as the logical improvement of Atanasoff's invention, employing the same principles of logic.

The Turing machine 1936

Turing machine is a theoretical computing device conceived by Alan Turing in 1937. It started as an abstract computational device meant to investigate the extent and limitations of what can be computed. Turing intended the device to be used as a "universal machine" that could be programmed to duplicate the function of any other existing machine.In its simplest form, a Turing machine is composed of an infinitely long tape, made of paper. There is a head that can read the symbol, choose to write a new symbol in place, and then move left or right.

The machine resembled an automatic typewriter that used symbols for math and logic instead of letters. Turing was intended to be an universal machine that could be programmed to duplicate the function of any other existing machine. Turing's machine was the theoretical precursor to the modern digital computer.