COMP 372 Assgn. # 3 Different ROM and RAM IC's

ROM - Read-only memory: On ROM, data is prerecorded for read only which can not be removed. ROM is nonvolatile and it retains its contents regardless the computer is on or off.

RAM - Random access memory: whose contents can be accessed (read, write and remove) in any order. This is in contrast to sequential memory devices such as magnetic tapes, discs and drums, in which the mechanical movement of the storage medium forces the computer to access data in a fixed order. RAM is usually used for primary storage in computers to hold active information such as data and programs. Common forms of RAM are: SRAM (Static RAM) and DRAM (Dynamic RAM).

There are also some hybrad memory types which combines characters of both RAM and ROM, such as Flash memory, NVRAM and EEPROM.

Type	Volatile	Writeable	Erase Size	Max Erase Cycles	Speed
SRAM	Yes	Yes	Byte	Unlimited	Fast
DRAM	Yes	Yes	Byte	Unlimited	Moderate
Masked ROM	No	No	n/a	n/a	Fast
PROM	No	Once, with a device programmer	n/a	n/a	Fast
EPROM	No	Yes, with a device programmer	Entire Chip	Limited	Fast
EEPROM	No	Yes	Byte	Limited	Fast to read, slow to erase/write
Flash	No	Yes	Sector	Limited	Fast to read, slow to erase/write
NVRAM	No	Yes	Byte	Unlimited	Fast

Computer Memory: RAM and ROM

Related Terms:RAM, ROM, Flash memory, DRAM, SRAM

References

http://www.networkdictionary.com/hardware/cm.php

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