Difference between RAM and ROM

Computer Engineering Computer Network MCA

In computer systems, memory is a hardware component of the system that stores data and information in the computer. The computer memory can be classified into two main types namely – primary memory and secondary memory. The primary memory is further divided into two main types – RAM and ROM.

Read through this article to find out more about RAM and ROM and how they are different from each other. Let's start with some basics of RAM and ROM.

What is RAM?

RAM stands for Random Access Memory. RAM is a type of primary memory of a computer system. RAM is used in a computer to store those parts of data and instructions on which the computer is currently working. RAM is a volatile memory which means its data is lost when the computer is turned off. RAM stores its data temporarily.

RAM is also known as the main memory of the computer because the CPU of the computer can access all memory cells of the RAM directly. In modern computer, RAM is made up of semiconductor materials and found in the form of ICs

What is ROM?

ROM stands for Read Only Memory. It is also a type of primary memory of the computer. It is used to store those parts of computer instructions and programs that do not required to be changed like BIOS. Therefore, ROM is used to make computer firmware. Generally, data is stored in the RAM during the process of manufacturing. ROM is also a type of semiconductor memory and built in the form of ICs.

ROM stores the data permanently, thus it is a non-volatile memory which means it holds the data even when the computer is switched off. The CPU of the computer can only read data from the memory cells of ROM, but cannot change.

Difference between RAM and ROM

Both RAM and ROM are the primary memories of the computer, however they are quite different from each other. The important differences between Random Access Memory (RAM) and Read Only Memory (ROM) are highlighted in the following table −

Parameter	RAM	ROM
Full Form	RAM stands for Random Access Memory.	ROM stands for Read Only Memory.
Definition	RAM is a primary memory of the computer that stores those data and instructions on which the CPU is currently working.	ROM is a primary memory of the computer that stores those computer instructions and programs that do not need to be altered in future like BIOS.
Nature	RAM is a volatile memory. Which means it stores data as long as power is on.	ROM is a non-volatile memory that means it stores data permanently even when power is off.
Data Access	The CPU of the computer can read, write, or alter the data on RAM.	CPU can only read data from ROM, but it can write or change.
Usage	RAM is used to store data that CPU needs for current instruction processing.	ROM is used to store data that in needed to bootstrap the computer.
Types	There are two major types of RAM available – SRAM (Static Random Access Memory) and DRAM (Dynamic Random Access Memory).	Three types of ROM available – PROM (Programmable ROM), EPROM (Erasable PROM), and EEPROM (Electrically EPROM).
Speed	The speed of RAM is quite high.	The speed of ROM is slower than RAM.
CPU Access	CPU can access data stored on RAM directly.	Data to be copied from ROM to RAM so that CPU can access its data.
Capacity	RAM memory is large and high capacity.	ROM is generally small and of low capacity.
Used as	RAM is used as CPU Cache, Primary Memory.	ROM is used as firmware by microcontrollers.
Cost	RAM is costly.	ROM is not so expensive.

Conclusion

The most significant difference between RAM and ROM is that RAM is a volatile memory, while ROM is a non-volatile memory. A memory is said to be volatile if its data is lost with the loss of power supply.