The types of secondary storage devices in a computer are – magnetic disk; floppy disk & magnetic tape. These three are the basic types of secondary memories in a computer that we normally see. But nowadays there are other types of memory in the market, like flash drives or SSD( Solid State Drives) etc. But the magnetic disk is the most used secondary memory, as its capacity is much more than the floppy and magnetic disk and less costly than SSD and flash drives.
(i). Magnetic Disk:– It is a flat circular platter with a metallic coating that rotates and there is a piny heat which reads and writes the data on the disk. It is a random access device, the read and writes head can be moved to any location in the platter. The surface of the magnetic disk is divided into sectors or blocks. Each of it has a unique address to facilitate the location of the rotating spindle. Data is recorded in the form of magnetized spots on the tracks of the disk, a spot representing the presence by ’1’ and its absence by ‘0’.
(i) Floppy Disk:– It is also called a flexible disk. These are used in the microcomputer system as well as mini computers. It is permanently sealed in a plastic-coated jacket and the whole package is inserted into the floppy drive for data transmission. It is cheaper than any other secondary storage device and is portable too. It is a low-cost device particularly used for pc systems. A floppy disk reader can be used to enter data into C.P.U once data has been recorded
(i) Magnetic Tape:– In this process, the reading and writing of data are done by a device called a tape drive and it is stored in sequential order. For example, if the payroll file is to be stored on a magnetic tape, the records would likely to be stored in the sequence of employment numbers. Hence, as a sequential access device, magnetic tapes can be referred to.