Is Abacus a computer?

Yes, it was an early mechanical computer. It is regarded as the first computer, made over 5000 years ago. An abacus is not like a modern computer. People think of a computer as an electronic, programmable device that can store, retrieve, and process data. There were many computing devices prior to the electronic computer that had processing capabilities. They were mechanical devices and are computers. There are many different kinds of computing devices and an abacus is one of them.