RAM vs ROM

RAM:

• RAM stands for the Random Access Memory.
• RAM devices are volatile type of memory, information lost power is off.
• RAM starts after Computer starts running.
• RAM have multiple lines and are said to be 8-Bit or 16-Bit.
• RAM is used to store the frequently accessing data by computer from ROM.
• There are two types of RAM
• DRAM
• SRAM

DRAM:

• Stands for Dynamic Random Access Memory.
• DRAM contains Capacitor and Transistor.
• Basically called as standard RAM
• DRAM must be frequently refreshed every few milliseconds.
• Example of DRAM is DDR RAM  

SRAM:

• Static Random Access Memory that retains data bits in its memory as long as power is being supplied.
• SRAM provide faster  access to the data and is more expensive.
• SRAM is used for the cache memory in computer and digital to analog converter on a video card.

ROM:

• Type of non-volatile memory used in computers and other electronic devices.
• ROM holds memory even if computer is off.
• ROM  chips are essential for the basic input/ output system (BIOS), boot up, reading and writing to peripheral devices.
• There are three types of ROM:
• EEPROM
• EPROM
• PROM

EEPROM:

• EEPROM stands for Electrically Erasable Read Only Memory.
• EEPROM is a type of  ROM which can be programmed and modified.
• EEPROM limited to single byte operations, which  made them slower.
• EEPROM need not be removed from board to modify.

EPROM:

• EPROM is Erasable Programmable Read Only Memory.
• EPROM can be erased and re-used. 
• Erases the data by Ultraviolet signals.

PROM:

• PROM stands for Programmable Read Only Memory.
• That can be modified once by user to allow a microcode program.
• If you need to change any thing, need to remove the ROM chip entirely.