All About is RAM and ROM

RAM or Random Access Memory is a form of computer memory that can be read and can be changed in any type of order by user which is typically used to store working data and machine code.

It allows the data items to be both written or read in almost the same amount of time which is very irrespective of the data in the physical location of the system.

It contains multiplexing circuitry and de-multiplexing circuitry which are used to connect with the data lines right to the addressed storage for writing and reading the entry.

RAM devices have multiple data lines and are said to be by people to be 8 bit, 16 bit OR 32 bit, etc devices when mostly more than one bit of storage is accessed.

Without RAM doing just about anything on any system would be slow or not run at all. RAM is quite different from the system’s storage, like it is a hard drive, where information gets stored for a long period of time.

What is ROM?

ROM or Read Only Memory is a type of non-volatile memory which is used in computers, laptops and other electronic devices where data is stored and can’t be modified electronically after the memory device is manufactured.

The contents of ROM will remain even after one turns off the computer unlike RAM.  It is a type of storage medium that permanently stores data and these days every computer comes with a small amount of ROM in it.

Read only memory is very useful for storing any kind of software that is hardly changed during the computer’s system life. ROM is hard-wired, such as a mask ROM integrated circuit or diode matrix, which can’t be electronically changed after the manufacture.

ROM is a computer memory chip which contains permanent or semi-permanent data in it. ROM is made to program needed to start devices like computers, laptops or mobiles, which is essential for boot-up. It can perform major output or input tasks.

Types of RAM


DRAM or Dynamic RAM which is pronounced as DEE-RAM is a widely used computer’s main memory.  The memory cell of DRAM is made up of transistor, a capacitor within an integrated circuit.

Since transistors leak small amounts, the capacitors slowly discharge, which causes stored information in the system to drain so DRAM has to be refreshed frequently few milliseconds to retain data from the transistors.

It stores information in the form of electric charges that is applied to capacitors as the information that is stored on the capacitors tends to lose over time and thus the capacitors must be recharged.


SRAM or Static RAM which is pronounced as ES-RAM is made up of four to six transistors which are memories that consist of circuits capable of retaining their state as long as the power is on.

Unlike DRAM which has to be refreshed periodically, SRAM keeps data in the memory as long as power is supplied to the system.  It is faster and more expensive which makes DRAM more common memory in the systems.

SRAM is called volatile memories. It is a type of semiconductor memory. When the memory is not powered up properly the data will eventually be lost from the system.

Types of ROM


PROM or Programmable ROM is a chip that data can be written only by a user once. It is manufactured as a blank memory. When a user buys a PROM, one will need a special device called a PROM programmer to write the desired data onto the blank PROM chip.

The process of programming PROM is sometimes called burning of the PROM in the memory which can be programmed just once after the manufacturing by blowing of the fuses. It is an irreversible process. Data in PROM cannot be changed and is permanent.


Erasable ROM is a special kind of ROM chip that has the opportunity to erase the programmed data, which the feature can be seen from its name itself.

The programmable ROM can be programmed to write data with a high voltage, and the data remains until it is exposed to the ultraviolet light for lasting up to longer than 10 minutes.

An EPROM can achieve this purpose, making it possible for memory reprogramming in the systems. It is a very special type of memory that holds on to its contents until it is exposed to ultraviolet light.


Electrically Erasable ROM is a kind of ROM that the concept of operation is very similar to EPROM which one has mentioned, but the ways to program and erase are done by uncovering EEPROM to an electrical charge.

No transparent window is needed in EEPROM and it can be erased and reprogrammed. So both programming and erasing will take about 4 to 10 milliseconds. Users can choose which to erase and program any location.

It can be erased one byte at a time instead of erasing the entire chip. It uses a pulsed voltage.

Difference between RAM and ROM

a)It cannot hold data permanently.It can hold data permanently.
b)RAM chips are volatile in nature.ROM chips are non-volatile in nature.
c)It is a read-write memory.It is a read only memory.
d)Data in RAM can be modified.Data in ROM cannot be modified.
e)It sizes from 64 MB to 4GB.It is comparatively smaller than RAM.

Difference between RAM speed and ROM speed


RAM Speed

ROM Speed


Writing data to RAM is faster.

Writing to ROM is much slower as compared to RAM.


RAM is a high-speed memory, with reading-write operations, happen at a fast pace.

ROM is a  slower speed memory which is less vulnerable to modification.


The data in RAM can be modified easily.

The data in ROM can be hardly or never be modified.


It loads the operating system and drivers for particular devices.

It is used for booting up the computer and to run initial diagnostics.


It is very fast but uses a lot of power.

It does not require flow of electricity to retain data.

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