Non-Volatile Computer Data Storage Device

References

http://en.wikipedia.org/wiki/Auxiliary_memory
- Auxiliary memory, also known as auxiliary storage, secondary storage, secondary memory or external memory, is used to store a large amount of data at lesser cost per byte than primary memory. They are two orders of magnitude less expensive than primary storage. In addition, secondary storage does not lose the data when the device is powered down — it is non-volatile. Another difference from primary storage in that it is not directly accessible by the CPU, they are accessed via the input/output channels. The most common form of auxiliary memory devices used in consumer systems is flash memory, optical discs, and magnetic disks. The latest addition to the auxiliary memory family is flash memory. This form is much faster as compared to predecessors, as this form of auxiliary memory does not involve any moving parts (it's completely digital). In some laptops, such as Apple's MacBook Air line and MacBook Pro with Retina Display line, solid state drives (SSDs) made from flash memory have replaced magnetic disk based hard disk drives (HDDs) that are found in most laptops. These 'chips' of memory are found below the trackpad in those laptops. However, it is much more expensive to get large capacity flash storage chips as opposed to HDDs, many of which are inexpensive. In addition, it is difficult for average users to replace these chips.