Memory is a storage part in a computer system. It is used to store the data, information, and programs at the time of processing on the computer. It stores data either temporarily or permanent. The main use of memory is saving and retrieving data.
Generally computer system consists of two types of memory −
It is called the internal memory of the computer. And it is also known as main memory or Temporary memory. It holds the data and instructions that are presently working on the system or by the CPU. Primary Memory is called volatile memory, because when power is switched off it loses all data.
Primary memory is generally of two types.
RAM (Random Access Memory) − It stands for Random Access Memory. RAM is a read /writes memory. It is referred as main memory of the computer system. It is a temporary memory. The information stored in RAM is lost whenever the power supply to the computer is switched off.
RAM is also of two types which are as follows −
Static RAM − Static RAM also known as SRAM. In this RAM the information is stored as long as the power supply is ON. SRAM are of higher coast and consume more power .They have higher speed than Dynamic RAM
Dynamic RAM − Dynamic RAM also known as DRAM, This type of RAM stores information in a very short time basically, a few milliseconds even though the power supply is ON. The Dynamic RAM is cheaper and of moderate speed and also they consume less power.
ROM (Read Only Memory) − It stands for Read Only Memory. ROM is a permanent type of memory. ROM information is not lost when power supply is switched off. The Content of ROM is inserted by the computer manufacturer and permanently stored at the time of manufacturing. ROM cannot be overwritten by the computer. It is also called Non- Volatile Memory.
ROM memory has three types’ names which are as following −
PROM (Programmable Read Only Memory) − It is used to write data once and read many. Once a chip has been programmed, the recorded information cannot be changed. It is a non-volatile memory.
EPROM (Erasable Programmable Read Only Memory) − EPROM chip can be programmed by erasing the information stored earlier in it. Information stored in EPROM exposing the chip for ultraviolet light.
EEPROM (Electrically Erasable Programmable Read Only Memory) − It is programmed and erased by special electrical waves in milliseconds. A single byte of data or the entire contents of the device can be erased.
It is an external memory of the computer. It is also known as Auxiliary memory or permanent memory. It is used to store different programs and the information permanently. We call it a non-volatile memory that means the data is stored permanently even if power is switched off.
The secondary storage devices are as follows −
Magnetic (Hard) Disk