Computer memory and Storage

Computer memory: -

Memory is an internal storage area in computer system. It hold data, instruction and intermediate result and supply these information to other units of computer when require. There are two type of memory use in computer are primary memory and secondary memory.

Primary Memory: -

Primary memory holds only those data and instruction on which computer is currently working. It has limited storage capacity and data is erased in case of power switched off. These are semiconductor memory and faster than secondary memory. 

Ex- RAM, ROM

RAM (Random Access Memory)- 

RAM is the internal memory of CPU for storing data, program and result. It is a read/write memory which store data until system is working and when system is switched off, data is erased. RAM is a volatile memory utilized by CPU. RAM is of two types

1. Static RAM (SRAM)
2. Dynamic RAM (DRAM) 

ROM (Read Only Memory)-

ROM is the internal memory holds instructions for starting up the computer. It is a non-volatile memory. The information is stored in ROM during manufacture. It is a memory from which we can only read but cannot write. The ROM is of following types.

1. PROM (Programmable Read Only Memory)
2. EPROM (Erasable Programmable Read Only Memory)
3. EEPROM (Electrically Erasable Programmable Read Only Memory)

Secondary memory:-

Secondary memory are used to store data and information permanently. It is also known as backup memory or auxiliary memory. These types of memories are internal or external storage devices either inside or outside the computer. We cannot store data permanently in primary memory and its costs is also higher than secondary memory. The secondary memory can be divided into- 

• Magnetic Storage- Hard disk, Floppy disk, Magnetic tape etc.
• Optical Storage- CD, DVD, BD  
• Solid State Storage- SSD, Memory Stick, USB Memory

Cache Memory:- 

Cache memory is an extremely high speed semiconductor small size memory that act as a buffer memory between the CPU and RAM. Cache memory holds those data and programs which are most frequently used by CPU. It consume less access time as compare to main memory and store data for temporary use.