Difference between RAM and ROM

We hear the terms RAM and ROM most commonly but are not exactly clear with both the terms. Most of the people don’t know the basic differences between them both. The present article explains various aspects of RAM and ROM. A comparison is made between both to clearly understand various aspects.

What is RAM?

RAM stands for ‘Random Access Memory’. Random access means that the processor can get access to any location of the hard disk memory directly. Hence, the name Random Access Memory is given.

Types of RAM:

The 2 types of RAM are Static RAM (SRAM) and Dynamic RAM (DRAM).

Static RAM (SRAM):

• Static RAM requires a constant flow of the power supply to the circuit. The data stored in it is retained through the continuous power supply.
• Interruptions in the power supply result in loss of data though.
• SRAM is made up of transistors and latches.
• SRAM is expensive and faster.
• Its main function is to act as cache memory for the computer. 

Dynamic RAM (DRAM):

• The word ‘Dynamic’ refers to the tendency of the stored charge to leak away, even in the presence of continuous power supply.
• DRAM needs to be refreshed to retain the data it holds due to the charge leakage property of the capacitors.
• The DRAM requires a separate circuit for refreshing purposes.
• Compared to SRAM, DRAM is slower in speed and cheaper in cost.
• DRAM is highly dense.

What is ROM?

ROM stands for ‘Read-only Memory’. The processor cannot access the raw memory directly. The data can be accessed only when it’s transferred to the RAM.

Types of ROM:

The 3 types of ROM are PROM, EPROM, and EEPROM.

1. Programmable ROM (PROM): The user can modify the Programmable ROM (PROM) only once. It is not erasable due to the presence of small fuses on the parent chip. These fuses are burnt open while programming.

1. Erasable and programmable ROM (EPROM): The content of the EPROM can be erased using the UV rays. The data is reprogrammed. The charge trapped during programming has no leakage path due to which it can be stored for up to 10 years.

Electrically erasable and programmable ROM (EEPROM): It can be erased and reprogrammed electrically for more than 100,00 times. It’s flexible but a little slower.

Characteristics of RAM:

• RAM is a volatile memory which means that data stored in the RAM volatilizes when there’s no power supply. At times of power cut, it only stores data that needs to be further processed.
• You can read, write, and erase RAM data as many times as you wish. It’s called a read-write memory of the computer. The processor reads the instructions from the RAM and writes the result to the RAM. This is how the data is modified in the RAM.
• The storage capacity of Random Access Memory (RAM) is high. It ranges from 64 MB to 16 GB.
• RAM is the fastest memory of the processor. Its expense is due to its high speed.

Differences between RAM and ROM:

• Property	RAM	ROM
  1.      Basic function	It is read-write memory	It is a read-only memory
  1.      Use	RAM is used to store data temporarily that has to be currently processed by the CPU Primary Memory, CPU cache	It stores the instructions required for the bootstrapping process BIOS, RFID, or UEFI
  2.      Data Modification	Data is modified easily	Data is not modified
  3.      Capacity size	High capacity	Small capacity
  4.      Volatility	RAM is volatile	ROM is non-volatile
  5.      Types	2 types namely Dynamic RAM and static RAM	3 types namely PROM, EPROM, and EEPROM
  6.      Cost	RAM is expensive	ROM is comparatively cheaper
  7.      CPU interactions	Data is accessed by the CPU	Data is not accessed by the CPU directly
  8.      Speed	Fast	ROM is comparatively slow
  9.      Power consumption	Consumers’ high power	Consumes little power
  10.  Data storage	Temporary	Permanent

Frequently Asked Questions