Why ABC is considered electro-mechanical computer?

The Atanasoff-Berry Computer (ABC) is considered an electro-mechanical computer due to its use of both electrical and mechanical components for computation. Here’s why:

1. Electrical Components: The ABC made use of vacuum tubes for digital computation, making it one of the earliest electronic computing devices. Vacuum tubes were used to perform logical operations and store data. This electronic aspect is a fundamental part of what makes a computer like the ABC distinct from purely mechanical computing machines of earlier eras.

2. Mechanical Components: In addition to its electronic aspects, the ABC utilized mechanical components for input and output processing. It used punched cards (a mechanical storage medium) for input and output, and it also had mechanical rotating drums to store electrical charges (as memory) for the purposes of computing. These rotating drums represent a blend of mechanical engineering and electrical storage principles, which marked a transitional phase in the evolution of computing technology from purely mechanical to electronic systems.

The combination of these electrical and mechanical elements in the ABC’s design is why it’s often referred to as an electro-mechanical computer. This hybrid approach was innovative at the time, laying groundwork for future developments toward fully electronic computers.