Difference Between RAM and ROM

Both RAM and ROM are the two major classifications of memory. The crucial difference between RAM and ROM is that RAM is a volatile memory thus stores data only till the time the power is switched on. While ROM is a non-volatile memory that retains data even when the power gets off.

classification of memory

Another major difference between the two is that RAM allows both read and write data operation. As against ROM allows read operation only.

Content: RAM Vs ROM

  1. Comparison Chart
  2. Definition
  3. Key Differences
  4. Conclusion

Comparison Chart

Basis for ComparisonRAMROM
Stands forRandom Access MemoryRead Only Memory
Memory typeVolatileNon-volatile
Memory capacity1 to 256 GB per chip4 to 8 MB per chip
Operation typeRead and Write both.Only Read.
SpeedFastComparitively slow.
Storage typeTemporaryPermanent
Also referred asPrimary memorySecondary memory
Presence of data according to power sourceThe stored data in RAM lost in case of power failure.Data retained in ROM even if the power is turned off.
Accessibility to processorProcessor can directly access the data in RAM.Processor cannot directly access the data in ROM.
CostHighComparitively low

Definition of RAM

RAM is an abbreviation used for Random Access Memory. It allows read and write operation of data by the user. It is referred to as temporary memory because the data present in this memory last only till the time the power supply is on. As once the supply gets off then the data present in it gets automatically cleared and cannot be restored.

It stores program or data of any recent on-going operation inside the system. And thus this memory allows the processor to read and write the data.

SRAM and DRAM are its two major classifications. SRAM stands for static random access memory. While DRAM is dynamic random access memory.

Definition of ROM

ROM is an acronym used for Read-Only Memory. Here the name itself is indicating that only read operation can be performed on this memory. This means the data in ROM is stored at the time of designing the system and hence user does not hold the authority to change the data present in it. The data in this particular memory is stored on a permanent basis thus power failure neither modify nor delete the data or program stored in this particular memory location.

Basically bootstrap programs are stored by ROM that comes into action once the system gets turned on. And thus processor does not hold the ability to directly access this memory.

However, the data in ROM can be rewritten. But this is done only by the use of some specific methods. And according to these methods, ROM is majorly classified as PROM, EPROM and EEPROM. Programmable read-only memory is abbreviated as PROM, erasable programmable read-only memory is abbreviated as EPROM and electrically erasable programmable read-only memory is abbreviated as EEPROM.

Key Differences Between RAM and ROM

  1. RAM is a temporary storage type of memory as data lasts only till the time the power supply is on. On the contrary, ROM is a permanent memory that retains the data for a longer duration.
  2. Random-access memory is volatile in nature. But read-only memory is non-volatile in nature.
  3. The operating speed of RAM is faster than the ROM.
  4. RAM is classified as the primary memory of the system. However, ROM is categorised as the secondary memory.
  5. RAM offers memory capacity in GB usually 1 to 256 GB per chip. On the contrary, ROM permits the storage capacity in MB, usually in the range 4 to 8 MB per chip.
  6. RAM stores data on transistors thus requires a continuous source of power. While data stored in ROM remain unaffected with power failure.
  7. The data stored in RAM is changeable by the user. Whereas the data in ROM cannot be altered by the user.
  8. RAM offers the user to read as well as write data but data in ROM is pre-written and thus can only be read by the user.
  9. The processor can directly access the data present in RAM. However, the data present in ROM do not permit direct access to the processor.
  10. The cost of Random access memory is comparatively higher than the read-only memory.


So we can say that due to different functionality both RAM and ROM are used by a system for proper and efficient performance.


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