求一篇关于计算机发展史的英语作文

The oldest calculating tool is abacus that was invented by Chinese several thousand years ago. Since then human beings had tried to make a machine to calculate for many years. However, there had been no machine which can be called "computer" till 1946. In that year two Americans invented the first computer in the world. The volumn of the machine was so large that it took up a whole room, and its speed was very low. With the rapid development of IT, nowadays computers are much smaller and faster, and they have become one of essential tools for everybody.