The Abacus: the first Computer

The abacus was used as a mathematical model for early electronic computers and so technically it was "the first handheld".
Its Mandarin name is "Suen Pan" also known as "calculating plate". It was invented around 1600 AD in China, however the inventor remains unknown. The Japanese also had a similar version of the abacus that they called "soroban": this was a more elegant version of the Chinese abacus.
During the Medieval period, the West picked up on the abacus. The Russian's abacus is in a horizontal direction while the Chinese and the Japanese's abacus is in a vertical direction: this was due to the fact that the Chinese and Japanese wrote downwards, while the West wrote across.
