SECONDARY STORAGE DEVICE
Secondary Memory: Secondary memory refers to the permanent storage of data. It is also known as backup memory. It has higher storage capacity than the primary memory. There are various types of secondary storage devices. Some of them are: 1.Magnetic Disk: Magnetic Disks are storage devices that are also made up of magnetic coated material. The surface of each disk is marked with invisible circular tracks. The data is stored in the form of magnetic spot on disk. Hard Disk : It is the most widely used internal storage magnetic disk. It is made up of spindles of smooth metallic plates coated with thin layer of magnetic material. Each plate of a hard disk is called a platter . Each platter has two (read/write) heads, one on each side. It has high storage capacity and is much faster which provides an easy access to data. Hard disk is also known as Winchester Disk. Hard Disk is invented by ‘Reynold Johnson’ at IBM in 1956. Seagate is the 1 st company to ship the hard dis