- ROM stands for Read Only Memory. The memory from which we can only read but cannot write on it.
- This type of memory is non-volatile. The information is stored permanently in such memories during manufacture.
Usage :
- ROM chips are not only used in the computer but also in other electronic items like washing machine and microwave oven.
Types of ROM :
- MROM
- PROM
- EPROM
- EEPROM.
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| Types of ROM |
1.MROM :
- MROM stands for Mask Read Only Memory.
- Mask ROM (MROM) chips contain a software mask that contained a pre-programmed set of data or instructions. These kind of ROMs are known as masked ROMs which are inexpensive.
Usage :
- Mask ROM can give the high storage density making it a cheap solution for high volume applications.
- Less expensive.
2.PROM :
- PROM stands for Programmable Read Only Memory.
- PROM is read-only memory that can be modified only once by a user. The user buys a blank PROM and enters the desired contents using a PROM program.
- PROM can be programmed only once and is not erasable.
Usage :
-
It is not possible to do changes on existed data, so it's essentially impossible to 'remove' the contents.
Drawback :
- No re-usability.
3.EPROM :
- Erasable and Programmable Read Only Memory.
- The EPROM can be erased by exposing it to ultra-violet light for a duration of up to 40 minutes. Usually, an EPROM eraser achieves this function.
Usage :
- Re-usability is their.
Drawback :
- Time taken for erasing data.
- Mask ROM can give the high storage density making it a cheap solution for high volume applications.
- Less expensive.
2.PROM :
- PROM stands for Programmable Read Only Memory.
- PROM is read-only memory that can be modified only once by a user. The user buys a blank PROM and enters the desired contents using a PROM program.
- PROM can be programmed only once and is not erasable.
Usage :
- It is not possible to do changes on existed data, so it's essentially impossible to 'remove' the contents.
Drawback :
- No re-usability.
3.EPROM :
- Erasable and Programmable Read Only Memory.
- The EPROM can be erased by exposing it to ultra-violet light for a duration of up to 40 minutes. Usually, an EPROM eraser achieves this function.
Usage :
- Re-usability is their.
Drawback :
- Time taken for erasing data.
4.EEPROM :
- EEPROM stands for Electrically Erasable Programmable Read-Only Memory.
- The EEPROM is programmed and erased electrically. It can be erased and reprogrammed about ten thousand times. Both erasing and programming take about 4 to 10 ms (milli seconds).
Usage :
- Less time taken for erasing the data.
- EEPROM is a stable, non-volatile memory storage system that is used for storing minimal data quantities in computer and electronic systems and devices
Advantages of ROM :
- Non-volatile in nature.
- these can't be accidentlly changed.
- cheaper than RAM's.
- Easy to test.
- More reliable than RAMs.
Difference between RAM and ROM :
| DIFFERENCES | RAM | ROM |
|---|---|---|
| Stands for | Random Access Memory | Read Only Memory |
| Usage | RAM allows the computer to read data quickly to run applications. It allows reading and writing. | ROM stores the program required to initially boot the computer. It only allows reading. |
| Volatility | RAM is volatile i.e. its contents are lost when the device is powered off. | It is non-volatile i.e. its contents are retained even when the device is powered off. |
| Types | The two main types of RAM are static RAM and dynamic RAM. | The types of ROM include PROM, EPROM and EEPROM. |
