ABACUS

The abacus (plural Abaci or Abacuses), also called a counting frame, is a calculating tool used primarily in parts of Asia for performing arithmetic processes. Today, abaci are often constructed as a bamboo frame with beads sliding on wires, but originally they were beans or stones moved in grooves in sand or on tablets of wood, stone, or metal. The abacus was in use centuries before the adoption of the written modern numeral system and is still widely used by merchants, traders and clerks in Asia, Africa, and elsewhere. The user of an abacus is called an abacist.

NAPIER'S BONE

Napier's bones, also called Napier's rods, are numbered rods which can be used to perform multiplication of any number by a number 2-9. By placing "bones" corresponding to the multiplier on the left side and the bones corresponding to the digits of the multiplicand next to it to the right, and product can be read off simply by adding pairs of numbers (with appropriate carries as needed) in the row determined by the multiplier. This process was published by Napier in 1617 an a book titled Rabdologia, so the process is also called rabdology.
There are ten bones corresponding to the digits 0-9, and a special eleventh bone that is used the represent the multiplier. The multiplier bone is simply a list of the digits 1-9 arranged vertically downward. The remainder of the bones each have a digit written in the top square, with the multiplication table for that digits written downward, with the digits split by a diagonal line going from the lower left to the upper right. In practice, multiple sets of bones were needed for multiplication of numbers containing repeated digits.

CHARLES BABBAGE

Charles Babbage (1791-1871), computer pioneer, designed two classes of engine, Difference Engines, and Analytical Engines. Difference engines are so called because of the mathematical principle on which they are based, namely, the method of finite differences. The beauty of the method is that it uses only arithmetical addition and removes the need for multiplication and division which are more difficult to implement mechanically.

SCHICKARD CALCULATING CLOCK

A 1623 letter from William Schickard to astronomer Johannes Kepler is the only surviving record of Schickard’s calculator.
Schickard combined Napier’s Bones, for multiplication and division, with a toothed-wheel system to add and subtract. It is the earliest known mechanical four-function calculator.

SLIDE RULE

The slide rule (often nicknamed a "slipstick") is a mechanical analog computer, consisting of calibrated strips, usually a fixed outer pair and a movable inner one, with a sliding window called the cursor. It was the most commonly used calculation tool in science and engineering. Their use began to wane as computers were introduced, starting in the 1950s, and the scientific calculator made them largely obsolete by the early 1970s. Despite their similar appearance, a slide rule serves a purpose different from that of a standard ruler: a ruler measures physical distances and aids in drawing straight lines, while a slide rule performs mathematical operations.

THE PASCALINE

Blaise Pascal is credited with inventing a calculator, advanced for its time, called the Pascaline.
In 1642, Blaise Pascal, while only eighteen years old invented a device to help his father who worked as a tax collector do his job. Pascal invented one of the first calculators called the Pascaline. The Pascaline was only able to do addition with ease. It used 8 dials to add numbers up to 8 figures long. As one dial moved to 10 notches it moved the next dial up a notch. The photo to the right is an actual Pascaline signed by Blaise Pascal himself.

PUNCHED CARD

In 1881, Herman Hollerith began designing a machine to tabulate census data more efficiently than by traditional hand methods. The U.S. Census Bureau had taken eight years to complete the 1880 census, and it was feared that the 1890 census would take even longer. Herman Hollerith invented and used a punched card device to help analyze the 1890 US census data. Herman Hollerith's great breakthrough was his use of electricity to read, count, and sort punched cards whose holes represented data gathered by the census-takers. His machines were used for the 1890 census and accomplished in one year what would have taken nearly ten years of hand tabulating. In 1896, Herman Hollerith founded the Tabulating Machine Company to sell his invention, the Company became part of IBM in 1924.
Herman Hollerith first got his idea for the punch-card tabulation machine from watching a train conductor punch tickets. For his tabulation machine he used the punchcard invented in the early 1800s, by a French silk weaver called Joseph-Marie Jacquard. Jacquard invented a way of automatically controlling the warp and weft threads on a silk loom by recording patterns of holes in a string of cards.
Hollerith's punch cards and tabulating machines were a step toward automated computation. His device could automatically read information which had been punched onto card. He got the idea  and then saw Jacquard's punchcard. Punch card technology was used in computers up until the late 1970s. Computer "punched cards" were read electronically, the cards moved between brass rods, and the holes in the cards, created a electric current where the rods would touch.