Various types of primary memory for project-computer world

Various types of primary memory for project

Primary memory : Primary memory holds only that data and instruction on which the computer is currently working. It is made up of semiconductor device. In this memory data is lost when power switched of. These memory are not as fast as registers. It is a temporary storage area built into the computer hardware. Physically, this memory consist of some integrated circuit chips either on the motherboard or on a small circuit board attached to a motherboard to a computer system.This memory is divided into two subcategory's : 

1. RAM(Random access memory)
2. ROM(Read only memory)  

1. RAM(Random access memory) : RAM consist of some integrated circuits. Computer's motherboard is design in a manner that its memory capacity can be enhanced easily by adding more memory chips.  Random access memory is a form of computer memory that can be read and change in any any order typically used to store working data and machine code.

RAM is divided into two types

  1. DRAM(Dynamic Random access memory) : DRAM the term dynamic indicate that the memory must be contently referred and it will loss is contains.  DRAM is typically used for the main memory in computing devices. All DRAM  chips have to referred every few milliseconds by rewriting the data to the module. In other word we can say that DRAM is a type of Random Access semiconductor memory that stores each bit of data in a memory cell consisting of a tiny capacitor and a transistor the capacitor can either be charged or discharged these two states are taken to represent two value of BIT (0 and 1).

 2. SRAM(Static Random access memory) : Static RAM is volatile memory  and used in Cache memory and registers because  it is faster and does not require refreshing like DRAM. Static ram is able to operate at highest speed then DRAM. DRAM is used for a Computer main memory. SRAM is said to be static because it does not to be refresh.

Characteristics of static ram

1. Long life
2. No nee to refresh
3. Used as cache memory
4. Its size is large
5. Its power consumption is high

Characteristics of Dynamic RAM

1. Its short data life time 
2. Need to be refresh continuously
3. Slower as compare to SRAM
4. Smaller in size as compare to SRAM
5. Used as RAM
6. Less expansive then SRAM
7. Its power consumption is low

2. ROM(Read only memory) :  The memory from which we can only read but can not write on it this type of memory is non-volatile. Then information is stored permanently in such memory during manufacture. A ROM stores such information that are required to start a computer .Rom chip are not only used in computer but also in other electronic items washing machine, microwave oven storing data permanently into this this kind of memory is called "burning the data" because in such memory is stored by using fuse link.

ROM are classified in following categories : 

1. PROM( Programmable read only memory) 
2. EPROM( Erasable and  Programmable read only memory) 
3. EEPROM(Electrically Erasable and Programmable read only memory) 

PROM( Programmable read only memory) : The information recorded in PROM can only be read. PROM is also non-volatile storage. So we can say that PROM is read only memory that can be modified only once by a user. The user buys a blank PROM and enter the desired content using a PROM program it can be program only once and it is not erasable.

EPROM( Erasable and  Programmable read only memory) : Information stored in a ROM or PROM chip can not be changed. It is possible to erase information stored in an EPROM chip can be reprogrammed to store new information EPROM can be erased.  

EEPROM(Electrically Erasable and Programmable read only memory) : EEPROM is programmed and erased electrically it is also known as flash memory because of the easy method with which program store in it can be altered. It can erased and reprogrammed about ten times. Both erasing and programming take about 4 to 10 millisecond.