Explain the Primary memory of a computer?

The memory unit of computer used to store data and programs. Thus, it can be stored in Computer’s Storage Units. 

Computer Memory, thus divided into

1) Primary or main memory

2) Secondary memory

PRIMARY MEMORY:

1. It is essential component of a computer containing the programs as well as data.

2. Primary memory in the computer provides very fast access

3. The primary memory is used to store data and programs currently required for processing.

4. This memory is manufactured by using Integrated electronic chips (IC Chips)

5. The memory contains thousands of registers contain number of flips flops.

The Primary memory of the computer is further divided into two parts.

i) Random Access Memory (RAM)

ii) Read Only Memory (ROM)

Both RAM and ROM are random access memories and both can be used for reading purpose. The distinguish feature is, RAM has ability to change the data stored in its memory, which is not possible with ROM Memory.

Typically RAM is used to store system instructions which are permanent in nature. 

RANDOM ACCESS MEMORY: 

1. The word random means the computer access any memory cell directly from reading or writing data. 

2. It deals with the current information that are working presently 

3. Using this primary memory, the user can able to read or write data and programs in C.P.U

4. When the computer is switched off, the information contain in this memory it completely erased and that’s why it is called Volatile memory. 

5. The information exists in the RAM memory as long as the power supplied continuously to the computer. 

The RAM is again divided into two types 

i) SRAM (Static RAM)

ii) DRAM (Dynamic RAM)

1. SRAM and DRAM are the advanced memories of RAM. These SRAM and DRAM memories are used to increase the execution speed of a computer 

2. SRAM chips are used for special applications whereas DRAM chips are used in the Primary storage section of the computer. 

3. SRAM chips are expensive and occupy more space 

4. SRAM chips can have more transistors.

DRAM:- It is a recent innovation in the technology .The DRAM memory can pack the data in higher density. They occupy less space and cheap in cost. 

READ ONLY MEMORY: 

1. This memory use metal oxide semi-conductor technology. RAM can both read and write the information in its memory, where as ROM is read only memory. 

2. The content which are stored in ROM are not changed by the user. 

3. The information is not lost even though the computer is switched off. That’s why it is called as Non –Volatile memory. 

The ROM can be further divided into 

i) Programmable read only memory (PROM)

ii) Erasable programmable read only memory (EPROM)

iii) Electrically erasable programmable read only memory (EEPROM)

1. PROM:-

1. A ROM memory on which the user can write his own information. Such ROM’s are called programmable read only memory. 

2. Programming is done by using special writing circuits.

3. In Programmable read only memory, the programmer write only once the information and a PROM cannot be change.

2. EPROM: - 

Erasable programmable read only memory can be erased and reprogrammed by the user. The information in a PROM can be erased by passing a strong and shining Ultraviolet Rays (UV rays). After the PROM is exposed to UV rays, all bits are erased and become “O” (Zero).

3. EEPROM: - 

In this memory, electrical pulses are used instead of UV rays to erase PROM memory and can be reprogrammed repeatedly.