NVRAM – It is non-volatile RAM. It created by the combination of a static RAM and an electrically erasable PROM (EEPROM) in the same chip. The EEPROM and static RAM have exact mirror memories structure of each other. Upon powered it functions as a normal RAM. In case of power failure, it saves the stored data in the EEPROM. The entire contents of the RAM can be transferred in parallel to the EEPROM in less than 4 ms. When repowered it is possible to get entire contents of EEPROM back into the RAM. Thus EEPROM is used for temporary storage data during power failure. The STORE and RECALL signals are used to store data in EEPROM and transfer data back into RAM, respectively.
The main advantage of NVRAM is that a battery backup is not required to save working data in case of power failure.
Information such as time, date, monitor setting and other computer configurations are normally stored in the CMOS static RAM or NVRAM of a computer. Some standard NVRAMs and their capacities are listed below :