Difference between Primary Memory and Secondary Memory

We all know the importance of computer memory and its role. Computer memory is a storage device that allows us to store information or data for future reference. We all come across information or some important data that might be very useful, and this memory provides a place where we all can feed the facts and figures. In other words, we can say it helps in programming the details. Therefore, here we come with two known memories: Primary memory and Secondary memory.

Primary Memory

The computer's main memory we generally refer to is Primary memory. It is the tool of the computer which stores data and holds information. It is also known as internal memory. This memory is made up of semiconductors, and thus the size of this memory is small. It is connected to the CPU (Central Processing Unit) and carries data which can be accessed faster than other memory.

The location of this memory is found on the motherboard, from where we can access data that can be read. It is costlier as it provides fast access to information, speed, and reliability. If we talk about the volatility of this memory, then it is volatile in nature. Though ROM (Read only memory) doesn't possess this character even though it comes under Primary memory.

Based on all these characteristics which it holds it is further divided into RAM (Random access memory) and ROM (Read only memory).

1. RAM (Random Access Memory)

As its name suggests, RAM is a random access memory that is temporary and not permanent. It is in charge of holding the data or information, but the time and period are short. It is normally a chip that is associated with Central Processing Unit. The information in it gets evaporated if it lacks power. It cannot run without power. If the computer is switched off, the information gets easily erased. It is further classified into SRAM (Static RAM) and DRAM (Dynamic RAM).

I) Static Random Access Memory (SRAM)

The word static means still when there is no motion. So, accordingly, this memory retains data only when it gets power, and when it lacks power, the information is unexpectedly erased. There is no requirement to refresh the data. It is large in size and exhibits long life; hence it is costly.

II) Dynamic Random Access Memory (DRAM)

It is more dynamic as it is needed to be refreshed. It is small but very helpful for storing information that can be used in the future. It is cheaper as compared to SRAM. Power is important as all the information will be loosed if it doesn't get power.

2. ROM (Read Only Memory)

Read-only memory is a permanent storage device. It is most reliable as the information is permanent once filled in. It doesn't need refreshing. As its name suggests, it can only be read and not written. The information is reprogrammed and can easily be deleted. It is further classified into many like PROM (Programmed Read Only Memory), EPROM (Erasable Programmable Read Only Memory), and EEPROM (Electrically Erasable And Programmed Read Only Memory).

I) Programmed Read Only Memory (PROM)

It is a memory that is empty when made and later programmed after manufacturing. In this, the data remains lasting. The information which is already filled stays permanently. It is used in video games, cell phones, etc.

II) Erasable Programmable Read Only Memory (EPROM)

In this memory, the information can be reprogrammed and repeatedly erased. The information is changeable. It comes in the window form. It is generally used in microcontrollers.

III) Electrically Erasable And Programmed Read Only Memory (EEPROM)

It is the excessive reprogramming that can be done countless times. It can be reprogrammed several times. Similarly, it can be erased too. It is generally used in computers. Like when the computer is turned on, it doesn't get open immediately. It takes time, so this time consumed is due to this memory. These days flashback is used as a substitute for that memory.

Secondary Memory

Contrary to Primary memory, we have Secondary memory. Secondary memory plays the same role as Primary memory, like storing and holding data, but the information remains permanent here. It is called auxiliary memory. Secondary memory is the exact opposite of Primary one. The size of this memory is bigger, and it is less costly than primary memory. If we talk about volatility, then it is non-volatile in nature. That is the information that is stored remains and doesn't evaporate. This memory is not directly connected to Central Processing Unit; thus, the computer cannot access it easily. The information used here can be transferred and refrained. The function that Secondary memory plays is that it has large storage, which means there is enough space to hold information or data. It is more portable where the data can be stored or easily accessed, and simultaneously it can be removed if the need arises. It could also be transferred.

Based on storage is classified into Fixed storage and Removal storage.

1. Fixed Storage

This is the internal media that helps in storing data. As its name suggests, it is fixed that the information here remains everlasting. It is used in Internal Flash Memory, Solid State Disk (SSD), and Hard Disk Drive (HDD).

2. Removal Storage

Removal storage is an external media device. It is used for storing data and could also be named a disk drive. Here, the information is inserted and, at the same time, can be transferred from one device to another. Information can be removed according to individual requirements. Removal storage mainly includes Optical disks (DVDs, CDs), Floppy disks, Paper Storage, Pen drives, etc.

Secondary Memory Devices

I) Floppy Disk

Magnetic devices are used for making floppy disks. It performs the same function that every Secondary memory device does of storing information and data. The data here is transmitted from one device to another. It has a size of 3.5 inches with a storage capacity of 1.44 MB and a size of 5.25 inches with a storage capacity of 1.2 MB. A floppy disk can only be used when we have a floppy drive. But nowadays CDs and DVDs are being used in place of that.

II) Pen Drive

A pen drive is a popular device to store data which is further used when required. From this device, not only can data be stored, but it also can be transferred. To use a Pen drive, it needs to be connected to USB. The other name of the Pen drive is a flash drive. It comes in various storage like 1 GB, 2 GB, 4 GB, 8 GB, 16 GB, etc.

III) Solid State Disk (SSD)

Its nature is nonvolatile, so the data isn't easily erased. It is quite easy to use as it doesn't make any noises which might irritate. So, it has widely replaced Hard drives. It works faster and also needs less power.

IV) Security Digital Card (SD)

It is a digital card that stores information and data. It is there in mobile phones and cameras. The data can be viewed and transferred to another device. When stored in the chip, it can be viewed and seen anywhere.

V) Compact Disc (CD)

It is the other device that is secondary storage. It is circular in shape. A polycarbonate plate is used to make this. It contains a storage capacity of 700 MB. It can be CD-ROM (Compact Disc Read Only), meaning it can read but not write.

CDs are of two types:-

a) Compact Disc Recording (CD-R)

In this, once written data can be read but cannot perform the erasing function.

b) Compact Disc Rewritable (CR-RW)

It is unique where data can be written innumerable times and can be erased.