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Wiki Entry #1: Chinese Abacus

The Chinese abacus or the suan-pan was first documented around 1200 A.D. It, like all abaci, was created to help with calculations. An abacus is a mechanical aid for counting. An abacus is made of a wooden frame with a upper and lower deck separated by a horizontal beam. Vertical poles run from top to bottom through this beam. Beads, used for counting, are located on these poles and can be slid up or down on them. The Chinese abacus differs from other abaci because of the distribution of its beads. The suan-pan is a 2/5 abacus. This means that there are two beads in the upper deck and five in the lower. The beads in the upper deck have a value of 5 and the beads of the lower deck have a value of 1. Like our numbering system today the first pole was the ones position, the next to the right the tens, and hundreds and so forth. If one wished to use decimal places they chose a pole other then that of the far right as the ones position. The second bead on the upper deck was used temporarily when dividing, allowing for up to fifteen on one pole. When using a Chinese abacus one uses the thumb to slide a bead in the lower deck up and the index finger to slide it down. The middle finger is used to move beads in the upper deck. The abacus was not used for actual computation. The person doing the calculation used the abacus to keep track of figures while the whole calculation was done mentally.

The abacus is important in the development of digital computers. It was a necessary step on the path from counting with fingers to modern computers. Before devices like the abacus fingers were used for counting. When people began to need to count over ten, they used pebbles, sticks, or lines in the dirt to count. These items were difficult to transport however and that's where devices like the abacus came in. The next step was a 1/4 abacus created by the Japanese called the soroban. This simplified the abacus and removed some of the redundancy of the suan-pan such as the need for two upper beads.

Works Cited

Dalakov, G. (2012, January 22). History of computers and computing, calculating tools, the abacus. Retrieved from http://history-computer.com/CalculatingTools/abacus.html

Fernandes, L. (2012, August 11). Abacus. Retrieved from http://www.ee.ryerson.ca:8080/~elf/abacus/