What is a Primary Memory ?

This might be a new term for you because generally, we do not refer to memory as Primary and Secondary. Whenever we talk about memory we talk about RAM, ROM, Flash Memory, HDD, etc. But all these types of memories come under the category of Primary and Secondary memory respectively. Here in this blog post, we are going to have a detailed look into Primary memory and its types. But before looking into Primary Memory, let's just understand the types of memories.

Primary Memory

We generally have two types of Memories in our computers and these memories include:

1. Primary Memory: 

Primary Memory is a type of memory that is directly accessible by the Processor. Primary memory is faster than secondary memory and it also stores data that is frequently required by the system or the user. Primary memory improves the efficiency of the system by reducing the access time of the CPU. It loads those processes which are smaller and ready to use. By doing this it reduces the access time of the CPU and hence makes our computer faster. 

2. Secondary Memory: 

Secondary Memory is a type of memory that is accessible to the user and can be used to store the data of the user. It is generally slower than the Primary memory but holds more capacity than the primary memory. Computers come with bigger preinstalled secondary memory so that the user can store their data like Documents, Softwares, Media, etc., and can access them quickly within a few clicks. Secondary Memory generally includes devices such as Floppy, Hard Disk, CD-ROM, Magnetic Tape, SSD, etc.

Now coming back to Primary Memory let's discuss the types of Primary Memory and their classifications. There are generally two types of Primary memory:

(a). Read/Write Memory(R/WM or RAM): Read/Write Memory or RAM(Random Access Memory) is a type of memory that serves the purpose of Reading and Writing Data so that it can be frequently used whenever required. It is also called Random Access Memory because the microprocessor can randomly access the data from it. RAM is a volatile memory which means that it doesn't store the data permanently and loses it when the power is turned off. There are two types of RAMs which are given as:

(i). Static RAM: As the name Indicates, Static RAM is a type of Random Access Memory that is static because, in this type of Memory, the data remains stored till the power is supplied to the memory. It is made up of small digital circuits named Flip-Flops which store each bit as a voltage. This type of RAM has low density but offers high speed. Apart from it, this type of RAM consumes more power and is expensive as compared to the Dynamic RAM.

(ii). Dynamic RAM: This type of RAM is Dynamic because the information stored in this Memory leaks and needs to be refreshed again and again in a period of milliseconds. This RAM is made up of MOS(Metal Oxide Semiconductor) transistors, which store the bit in the form of a charge hence it needs to be refreshed again and again. Apart from Having High Density, it has lower power consumption and is cheaper than Static RAM.

Note: Refreshing of Dynamic RAM requires an extra circuit.

(b). Read-only Memory(ROM): Another type of primary memory is ROM which has its meaning in the name. It is a non-volatile memory that retains its information even after the power is turned off. It is generally used where data needs to be hardcoded and needed permanently. ROM also falls into two categories named Permanent Group which includes Masked ROM and PROM while the other group named Semi-Permanent includes EPROM and EE-PROM. Let's have a close look at each of them:

(i). Masked ROM: As the name indicates, Masked ROM permanently stores the bit pattern through a specialized process. The data stored in the Masked ROM by the Manufacturer can never be changed.

(ii). PROM(Programmable Read-Only Memory): In this type of ROM, the user can program the information into the chip. The writing of the ROM is called Burning and can be done with the help of a special PROM Programmer. 

(iii). EPROM(Erasable PROM(Programmable Read-Only Memory): As the name of this memory indicates, the EPROM can be written and Erased again and again with the help of Ultraviolet light. Reusability of the chip is its USP but erasing data from it is a little a bit tedious process.

(iv). EEPROM(Electrically Erasable PROM(Programmable Read-Only Memory): Like EPROM, it can also be used again and again but it has the advantage of altering the information by using electrical signals at the register level as compared to erasing all the information in EPROM. This also offers a Chip Erase Mode which can erase all of the data in milliseconds as compared to 15 to 20 minutes taken in EPROM. 

We hope this article about Primary Memory helped you.
Thanks for Reading !!

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