Describe different types of RAM and Rom.
Waht is RAM: RA< stands for random access memory. It is also called direct access memory Random access means that each individual byte in entire memory can be accessed directly. RAM is used to store data and instructions temporarily.
RAM is a volatile memory. It means that is contents are lost when the power is turned off. RAM is read/write memory. CPU can read data from RAM and write data to RAM. It is used to store data and instruction while it is being executed. RAM is also called main memory or primary storage.
Ram is built by using two different techniques:
- DRAM: DRAM stands for dynamic fandom access memory. It is a type of memory that is used in most computers. It is the least expensive kind of RAM.
DRAM requires an electric current to maintain its electrical state. The electrical charge of DRAM decreases with time that may result in loss of data. DRAM is recharged or refreshed again and again to maintain its data. The processor cannot access the data of DRAM when it is being refreshed. That is why it is slow.
- SRAM: SRAM stands for static random access memory. The memory cells are made from digital gates. Each cell can store data without any need of frequent recharging. CPU does not need to wait to access data from SRAM during processing. That is why it is faster than DRAM. It utilizes less power than DRAM. SRAM is more expensive. It is normally used to build a very fast memory known as cache memory.
What is ROM?
ROM stands for Read Only Memory. The instructions in ROM prepare the computer for use. These instructions can only be read but cannot be changed or deleted. It is not possible to write new information or instructions into the ROM.
ROM stores data and instructions permanently. When the power is switched off, the instructions stored in ROM are not lost. That is why ROM is known as non-volatile memory.
The information in ROM is stored by the manufacturer. When the computer is switched on, the instructions in ROM are automatically loaded into the memory of computer.
Types of ROM
Different types of ROM are as follows;
- PROM: stands for programmable read only memory. This form of ROM is initially blank. The user or manufacturer can write data and programs on it using special devices. The user can write data and instruction on it only once. If there is any error in writing the instructions, the error cannot be removed from PROM. The chip becomes unusable.
- EPROM: EPROM stands for erasable programmable read only memory. This form of ROM is initially blank. The user or manufacturer can write data and programs on it using special ultraviolet rays. The user then can write new program on it.
- EEPROM: EEPROM stands for electronically erasable programmable read only memory. In this memory, user can erase and write instructions with the help of electrical pulses. It there is any error in writing the instructions, the user can erase the contents electronically. The contents of EEPROM can be modified easily.