Difference between RAM and ROM: In this article, we are going to discuss the two different types of computer memory – RAM and ROM. We will compare both in details and at the end, we will discuss all the difference between RAM and ROM in details. In computer science, having a clear understanding of these two types of memory is very important. So, at first, we will discuss what is RAM and what is ROM and how they work. After getting a clear understanding of both we will move to the difference between RAM and ROM.
Basically, computer memory can be divided into two types – Primary memory and Secondary memory. RAM, ROM and cache memory are the primary memory and except these three, all other types of memories like hard disk, floppy etc are the secondary memory.
The cache memory is another type of semiconductor memory basically used to enhance the performance of the whole computer system. RAM and ROM are sometimes called main memory. The reason that RAM and ROM are called main memory because they can transfer data between them and the processor directly. But the hard disk and floppy disk can’t transfer data between them and the processor directly. so, they are called secondary memory. The data transfer between secondary memory and processor is done with the help of primary memory. Let’s discuss two major types of primary memory RAM and ROM first. After having a clear understanding of RAM and ROM, you will find all the major difference between RAM and ROM in table form.
What is RAM and What is ROM?
RAM and ROM both are the primary memory as we mentioned above. Now let’s talk more about the ram definition and also discuss what is ROM in details.
What is RAM - RAM definition (Random Access Memory):
RAM or Random access memory is a volatile memory or we can say it as temporary memory. The content or data stored in RAM deletes automatically when the power supply goes off. RAM requires continuous electrical power to retain its data. Once the data get deleted, we can’t recover it back unlike the secondary memory. In secondary memory like hard disk, we can recover the data back again if the data get deleted.
CPU can directly access any address location in RAM. That is why it is called random access memory. Due to random access, it is very quickly accessible. So, it is very fast as compared to secondary storage. RAM stores only those data which has to be currently processed. It can be used in both reading and writing mode. Basically, RAM is used for buffering purpose i.e. RAM is used when input-output operations are performed.
After cache memory, RAM is the fastest memory and after the hard disk or SSD; it is the largest memory available in a computer system. RAM is normally used to store data which are currently being processed by the CPU. That means when you open any application on your computer, it first loads on RAM and then it communicates with the CPU. Sometimes the whole application is loaded on RAM or sometimes the part of the application is loaded. Here the concept of virtual memory and cache memory is applicable in transferring application’s data from hard disk to RAM.
There are two types of RAM – SRAM and DRAM also known as Static RAM and Dynamic RAM respectively.
SRAM uses transistors and latches to store data. But DRAM uses transistors and capacitors to store the data. The main difference between Static RAM and Dynamic RAM is Static RAM requires a continuous flow electrical power to retain the data inside it. A power interruption may cause the loss of data in static RAM. Static RAM is faster and expensive than dynamic RAM.
Dynamic RAM requires a continuous refresh of charge to retain the data. Mainly, capacitors are used in the construction of dynamic RAM. Since the capacitor has a charge leakage property, a separate refresh circuit is required in dynamic RAM. Dynamic RAM is slower and cheaper than the static RAM.
What is ROM - ROM definition (Read Only Memory):
ROM or Read-only memory is a non-volatile memory. The content or data stored in ROM remains permanently until it is re-written. So it doesn’t depend on power. The data in ROM retains same until it is being altered by a user.
Unlike RAM, CPU can’t access the data directly from the ROM. At first, data gets transferred to the RAM and then CPU can access it. The capacity of ROM is comparatively smaller than RAM. It is also slower and cheaper than RAM. The CPU can only read the data from ROM. CPU can’t write or modified the data stored in ROM.
The ROM is mainly used for storing some instruction that the computer requires at the time of booting. So, if you don’t know about booting then it is a self-starting process where the necessary programs are loaded into the computer memory after power on or restart. It is generally used to store firmware data like BIOS for the hardware which are normally written in ROM at the time of manufacturing of the computer.
Basically, there are three types of ROM available – PROM, EPROM, EEPROM.
PROM stands for Programmable Read Only Memory. It can be modified only once by the user. The PROM chips come with some small fuses which are burned during programming and then fuses become open. That’s why PROMs are not erasable.
If a PROM can be somehow erasable, then it is called Erasable Programmable Read Only Memory. Normally, EPROM is erasable by using UV (Ultra Violet) rays and then it can be reprogrammed.
But if an EPROM is manufactured in such a way that it can be erasable electrically instead of using UV rays, then it is called Electrically Erasable Programmable Read Only Memory ie EEPROM.
Major difference between RAM and ROM in tabular form:
|RAM is a volatile memory.||ROM is a non-volatile memory.|
|It is a read-write memory.||It is a read only memory.|
|It is used to store currently processing data by the CPU temporarily.||It stores the data or programs which are required during booting.|
|CPU can easily modify the data stored in RAM.||CPU can’t modify the data stored in ROM.|
|Size of RAM is normally in between 64MB to 32GB.||Size of ROM is comparatively smaller than RAM.|
|There are two types of RAM – SRAM and DRAM.||There are three types of ROM- PROM, EPROM and EEPROM.|
|RAM is expensive.||ROM is comparatively cheaper than RAM.|
|It is used in buffering purpose.||It is not used in buffering purpose.|