The data and instructions that are entered into the computer system must be stored inside the computer before the real processing can start. In the same way the results formed after processing must also be stored before they can accept on to the output unit. The main memory of a computer is designed to supply to such needs. It provides space for storing data and instructions, space for storing transitional results and also space for the last results.
In other words we can say that “memory is a storage device which has store the data for future purpose”.
Types of Memory
There are two types of memory in Computer which are below:
1. Primary Memory
2. Secondary Memory
Primary Memory: Primary memory is called main memory of computer. It comes under internal memory and it is attached to CPU. It store data with program that execute. Primary memory is known as temporary memory because it does not store our data permanently. This memory is known as volatile memory because our data is safe in computer whenever light is continuing. When light is gone out data is lost. This memory is fast memory comparison as secondary memory.
There are two types of primary memory:
1. RAM
2. ROM
RAM: The full form of RAM is Random access memory. This is read write memory and known as volatile memory because our data is safe in computer whenever light is continue when light is gone our date is lost. There are two types of RAM
1. SRAM
2. DRAM
SRAM: SRAM means static random access memory and it stores the data whenever light is continued. It is costly and high speed memory comparison as DRAM. Light is more consumed like as DRAM.
DRAM: DRAM stands by Dynamic Random Access memory. Data is automatic lost after some time whenever light is continuing. It needs to refresh. DRAM is cheap and low speed memory comparison as SRAM.
ROM: ROM is read only memory, means it read data and cannot write/edit data. ROM is permanently memory and store many functions like sin, cosine, logarithms, square root etc.
There are three types of ROM
1. PROM: Programmable Read Only Memory
2. EPROM: Erasable Programmable Read Only Memory
3. EEPROM: Electrically Programmable Read Only Memory
Secondary Memory:
Secondary Memory is called external memory. It stores the data in computer permanently so it is called permanently memory. This is known as non volatile memory because data is safe after go the light. It is called auxiliary memory.
The main difference between main memory and secondary memory are:
1. Main memory stores data temporary whereas secondary memory store data permanently.
2. Main memory is the part of internal memory whereas secondary memory is the part of external memory.
3. Main memory is attached to CPU whereas secondary memory is not attached with CPU.
4. The speed of main memory is fast comparison as secondary memory.
5. Main memory is volatile memory whereas secondary memory is non volatile memory.
There are three types of secondary memory:
1. Magnetic Disc like floppy disk, hard disk,
2. Optical Disc like CD, DVD
3. Mass storage like pen drive