The Abacus
The abacus, shown in Figure 1.1, is a calculator; its first recorded use was circa 500 B.C. The Chinese used it to add, subtract, multiply, and divide. But the abacus was not unique to the continent of Asia; archeological excavations have revealed an Aztec abacus in use around 900 or 1000 A.D.
Figure 1.1 The first computer