Computer hardware and software, both are equally important. Hardware forms the computer, and software let it work.
Differences between optical and magnetic storage devices are how they store and retrieve data. Both devices are used for long term data storage. However, magnetic storage devices such as hard disk exists because of huge storage capacity and optical storage devices such as CD exists because of it’s portability feature.
An analog computer is a form of computer that uses the continuously changeable aspects of physical phenomena such as electrical, mechanical, or hydraulic quantities to model the problem being solved. As an analog computer does not use discrete values, but rather continuous values, processes cannot be reliably repeated with exact equivalence.