What are Primary Storage Devices
The primary storage devices are those which hold data and instructions that are required by processor to perform an operation. These storage devices are very high speed devices and the central processing unit can directly access it. These are also called inboard memory. The information in these devices is volatile in nature that is the information in these devices is retained only while the computer system is on. As soon as the computer system is turned off the information stored in the computer’s main memory is lost. The primary memory devices are very costly and have limited space. The most commonly used primary memory medium is RAM i.e. Random Access Memory. This memory is placed in a computer where the operating system, application programs and data in current use are kept so that they can be quickly reached by the computer’s processor.
RAM is much faster to read from the write to than the other kinds of storage in a computer’s like the Hard Disk, Floppy Disk and CD- ROM which are secondary storage devices. However, the data in RAM stays there only as long as your computer is running. When you turn the computer off, RAM loses its data. When you turn your computer on again, your operating system and the other files are once again loaded into RAM, usually from your hard disk. RAM is small, both in terms of its physical size and in the amount of data it can hold.
Computers with large amount of primary memory often perform faster simply because the CPU has not to sit idle waiting for data to be retrieved from slower components like hard drive and can be quickly stored in memory. RAM is of two types Static RAM and Dynamic RAM. ROM is also primary storage device. It is read only memory and it is non volatile in nature. It is a permanent storage. The contents of ROM cannot be altered. ROM is of 3 types that are PROM, EPROM and EEPROM. Cache memory also comes under primary storage devices. This memory is very small and of very high speed that resides very close to the CPU. Retrieving data from cache takes a fraction of the time that it takes to access it from main memory. Other than primary storage devices, we have secondary storage devices that allow us the facility for permanent storing of the information. Magnetic Tapes, Magnetic Disk, Floppy disk and CD-ROMs are some of the secondary storage devices.