RAM & ROM

 Random Access Memory (RAM) and Read Only Memory (ROM)





Memory is the most essential element of a computing system because without it computer can’t perform simple tasks. Computer memory is of two basic types – Primary memory(RAM and ROM) and Secondary memory (hard drive, CD, etc ). Random Access Memory (RAM) is primary-volatile memory and Read Only Memory (ROM) is primary-non-volatile memory. 



1. Random Access Memory (RAM) – 
 

  • It is also called read-write memory or the main memory or the primary memory.
  • The programs and data that the CPU requires during the execution of a program are stored in this memory.
  • It is a volatile memory as the data lost when the power is turned off.
  • RAM is further classified into two types- SRAM (Static Random Access Memory) and DRAM (Dynamic Random Access Memory).


2. Read Only Memory (ROM) – 
 

  • Stores crucial information essential to operate the system, like the program essential to boot the computer.
  • It is not volatile.
  • Always retains its data.
  • Used in embedded systems or where the programming needs no change.
  • Used in calculators and peripheral devices.
  • ROM is further classified into 4 types- ROM, PROM, EPROM, and EEPROM.

Types of Read Only Memory (ROM) – 
 

  1. PROM (Programmable read-only memory) – It can be programmed by the user. Once programmed, the data and instructions in it cannot be changed. 
     
  2. EPROM (Erasable Programmable read only memory) – It can be reprogrammed. To erase data from it, expose it to ultraviolet light. To reprogram it, erase all the previous data. 
     
  3. EEPROM (Electrically erasable programmable read only memory) – The data can be erased by applying an electric field, with no need for ultraviolet light. We can erase only portions of the chip. 
Difference between RAM and ROM



Sr. No.KeyRAMROM
1DefinitionRAM stands for Random Access Memory.ROM stands for Read Only Memory.
2Data RetentionRAM data is volatile. Data is present till power supply is present.ROM data is permanent. Data remains even after power supply is not present.
3Data AccessRAM data can be read, erased or modified.ROM data is readonly.
4UsageRAM 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.
5SpeedRAM speed is quite high.ROM speed is slower than RAM.
6CPU AccessCPU can access data stored on RAM.Data to be copied from ROM to RAM so that CPU can access its data.
7CapacityRAM memory is large and high capacity.ROM is generally small and of low capacity.
8UsageRAM is used as CPU Cache, Primary Memory.ROM is used as firmware by microcontrollers.
9CostRAM is costly.ROM is cheap.

Advantages of RAM and ROM

Some of the advantages of RAM are –

  • It increases the computer system speed, and the higher the system speed, the greater the RAM.
  • The CPU can read data quicker than the RAM. (Compared to hard disk, CD, DVD, FLOPPY, DISK, and USB)
  • There is very little use of battery life.
  • It can write and delete operations.

Some of the advantages of ROM are –

  • It is non-volatile and is cheaper than RAM
  • As they are static they do not need refreshing everytime.
  • Circuits are simple and ROM is more reliable than RAM.
  • Data can be stored permanently
  • It helps to start the computer and loads the OS.

Disadvantages of RAM and ROM

Some of the disadvantages of RAM are –

  • If the CPU wants to read the data from the RAM, then the data access from the registers and the cache is slow in comparison
  • RAM is volatile, i.e. it is difficult to store data forever.
  • It is expensive.
  • It has limited space.

Some of the disadvantages of ROM are –

  • ROM is read-only, cannot be modified.
  • If changes are required, it is not possible.

Which is the fastest memory?

RAM has a large size with an even higher power, while ROM is smaller in size and even less.

RAM is a high-speed memory, with read-write operations happening at a fast rate, whereas ROM is slower speed memory, which is less susceptible to alteration and can be done via an external program.

The Capacity of RAM and ROM

A ROM chip stores multiple MB (megabyte) of data, typically 4 to 8 MB per chip, whereas a RAM chip can store multiple GB (gigabyte) of data, ranging from 1 to 256 GB per chip.

Conclusion:-

In this article about RAM and ROM, we saw both of these have their own set of pros and cons.

Yet for a computer system to operate efficiently, all types of computer memory devices are mandatory.

ROM is inexpensive, can keep data on a permanent basis, but it has its own set of drawbacks such as hard to change the data for a fixed period of time.

RAM is costly but data can be altered several times on it at the same time.

 

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