<human>:  What is the history of abacus calculators and why did they fall out of popular use?
<bot>: The history of abacus calculators dates back to ancient times. It was used by many civilizations, particularly in the Middle East and China, as a simple form of calculation and record keeping. In fact, it is credited as the earliest form of a calculator, as its use dates as far back as 2500 BCE. As technology advanced, abacuses eventually fell out of popular use, as newer and more powerful mechanical and electrical methods of calculation became available in the 19th and 20th centuries.