Secondary memory is where programs and data are kept on a long-term basis. Common secondary storage devices are the hard disk and floppy disks. Secondary memory (or secondary storage) is the slowest and cheapest form of memory. It cannot be processed directly by the CPU. It must first be copied into primary storage (also known as RAM ). Secondary memory devices include magnetic disks like hard drives and floppy disks; optical disks such as CDs and CDROMs ; and magnetic tapes, which were the first forms of secondary memory.
Access Types of Storage Devices:
The information stored in storage devices can be accessed in two ways:
1. Sequential access
2. Direct access
1. Sequential access: Sequential access means the data is written or read in sequence one after another and can’t go directly to the desired location without going through all preceding locations. Example: Magnetic Tape
2. Direct access: Direct access devices are the ones in which any piece of data can be retrieved in a non-sequential manner by locating it using the data’s address. The device is called random access because any data from any location can be read or written directly. Example: Magnetic Disk.
