2014-10-31 03:11 PM
ROM is Read Only Memory is persistent memory that has usually has fixed content (program instructions, boot code, etc) and is updated very infrequently. The contents are not lost when power is removed.
RAM is memory that systems can write to and read from but the contents are typically non-persistent and disappear when power is removed.
Flash memory can operate as either RAM or ROM but the contents are persistent and are not lost when power is removed.