Memory Of a Computer System
Memory of a computer system is one of the vital part of a computer to perform many operations which needs storage medium.There is mainly two types of memory available in a computer system.
This memory is also called main memory of a computer system responsible for the small computer operations like copy paste and storing some useful instructions needed at the time of start of a computer system. This memory determines the speed of the computer also helps to increase computer working speed. Primary memory is again divided into two subcategories.
1.RAM (Random access memory)
2.ROM (Read only memory)
RAM (Random access memory)
This memory is responsible for the quick decisions taken by a computer. This memory is used for both Read and Write operations. This memory is called Volatile memory. All the Data saved in Ram is always temporarily stored. If the PC is switched off, all the information will be deleted. RAM is an integrated chip of rectangular size which is very much costly as comparison to secondary storage medium. Nowadays RAM chip available is 1 GB, 2GB, 4GB e.t.c.
RAM is again divided into two types
1. DRAM (Dynamic RAM)
2. SRAM (Static RAM)
It is the most common type of main memory. It is dynamic because each memory all quickly looses its charge so it must be refreshed hundreds of time each second to prevent data from being lost.
It is like DRAM but it is faster, larger and more expensive. It is static because it doesn't need to be continuously refreshed. Static RAM retains the store data as long as the power remain in whereas with dynamic RAM the stored information disappears after a few milliseconds.
Power consumption of DRAM is less than that of static RAM.
ROM (Read Only Memory)
ROM is also a type of memory in which only read operations is performed. Best example of ROM is Bios settings. Bios setting we can only read but we can't change its values.
There are two types of ROM
1.Erasable Memory. (EPROM, EEPROM)
2. Permanent Memory ( PROM)
EPROM (Erasable Programmable read only Memory)
All the information can be erased by exposing the chip to UV light through the window of the chip can be reprogram because the chip can be reused many times. This memory is suited for experimental projects.
Disadvantage Of EPROM
1.It is taken out of circuit to erase it.
2.Entire chip must be erased.
3.Erasing process takes 15-20 minutes.
EEPROM (Electrically Erasable read only memory)
It is similar to EPROM except that the information can be allotted by using electrical signals at the registered level rather than erasing of all the information. In this the entire chip can be erased in 10 minutes.
PROM (Programmable read only Memory)
This memory has poly silicon wires arranged in a matrix. This memory can be program by the user with a special PROM programmer that selectively burns the fuses according to the bit paths to be stored. In this information stored is permanent.
Secondary Storage Memory
This memory is also called auxiliary memory of a computer system responsible for all the date stored in computer system. This memory is also called storing medium of a computer system.
All the saved, stored data goes into Secondary storage medium. Best example for secondary storage are Pen-drive, Hard disks, Magnetic tapes e.t.c. The cost of secondary storage devices are cheaper than that of primary memories.
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