What Is a Storage Device?
A storage device is a component of a computer that stores general information and instructions.
Examples include hard disks, floppy disks, CDs, and memory drives. Storage devices are broadly classified into two main categories: main storage devices and auxiliary storage devices. Main storage devices are those that directly exchange data with the CPU, such as memory. Auxiliary storage devices are devices that exchange data indirectly with the CPU, such as hard disk drives (HDDs).
Types of Storage Devices
There are two types of main storage devices: non-volatile memory and volatile memory.
ROM, which is read-only, falls into the former category, while RAM, which is read-write, falls into the latter.
ROM is typically classified into two types: NAND flash memory and NOR flash memory. There are three main types of ROM media: USB memory, SD memory cards, and SSDs.
Other ROMs include mask ROM whose written contents cannot be changed, PROM that can be written only once, EPROM whose memory contents can be erased and rewritten by UV irradiation, and EEPROM whose memory contents can be erased and rewritten by applying high voltage. EEPROMs can be erased and rewritten by applying high voltage.
Storage Device Technology and Mechanism
There are two types of storage device access methods: random access and sequential access. The former is digital and can access any location, while the latter is a sequential access method like magnetic tape.
Classifications of storage device media include semiconductor, magnetic, optical, and paper. For example, HDD, floppy disks and magnetic tapes are typical for magnetic type, while for optical type, there are read-only ROM type for CD, DVD and BD, R type that can be written only once and RW type that can be rewritten as many times as necessary.