Bubble memory consists of what?

Bubble memory is a type of non-volatile memory technology that utilizes a very thin layer of magnetic material. This layer allows the storage of information in the form of tiny magnetic domains, or "bubbles," which can be manipulated and read using semiconductor technology. The semiconductor layer provides the necessary control and processing capabilities for managing the bubbles, making it an integral part of how bubble memory operates.

The defining characteristic of bubble memory is its ability to retain data without power, combining the benefits of both magnetic storage (which preserves information) and semiconductor technology (which allows for fast data access and manipulation). This technology was particularly useful during its time for applications where data integrity and power conservation were key considerations.

In contrast to bubble memory, the other options represent different forms of data storage technologies that do not align with the characteristics of bubble memory. For example, a layered structure of magnetic disks refers more to traditional hard drives, while liquid-based storage media and optical discs pertain to entirely different mechanisms of data storage unrelated to the bubble memory concept.