RANDON ACCESS MEMORY(RAM)

Random-access memory (RAM) is a form of computer data storage. Today, it takes the form ofintegrated circuits that allow stored data to be accessed in any order (i.e., at random). "Random" refers to the idea that any piece of data can be returned in a constant time, regardless of its physical location and whether or not it is related to the previous piece of data

By contrast, storage devices such as magnetic discs and optical discs rely on the physical movement of the recording medium or a reading head. In these devices, the movement takes longer than data transfer, and the retrieval time varies based on the physical location of the next item.

The word RAM is often associated with volatile types of memory (such as DRAM memory modules), where the information is lost after the power is switched off. Many other types of memory are RAM, too, including most types of ROM and a type of flash memory called NOR-Flash.

HISTORY

An early type of widespread writable random-access memory was the magnetic core memory, developed from 1949 to 1952, and subsequently used in most computers up until the development of the static and dynamic integrated RAM circuits in the late 1960s and early 1970s. Before this, computers used relays, delay line/delay memory, or various kinds of vacuum tube arrangements to implement "main" memory functions (i.e., hundreds or thousands of bits), some of which were random access, some not. Latches built out of vacuum tube triodes, and later, out of discrete transistors, were used for smaller and faster memories such as random-access register banks and registers. Prior to the development of integrated ROM circuits,permanent (or read-only) random-access memory was often constructed using semiconductor diode matrices driven by address decoders.

RAM DISK

Software can "partition" a portion of a computer's RAM, allowing it to act as a much faster hard drive that is called a RAM disk. A RAM disk loses the stored data when the computer is shut down, unless memory is arranged to have a standby battery power source.

SECURITY CONCERNS

Contrary to simple models (and perhaps common belief), the contents of modern SDRAM modules are not lost immediately when the computer is shut down; instead, the contents fade away, a process that takes only seconds at room temperatures, but which can be extended to minutes at low temperatures. It is therefore possible to recover any data stored in ordinary working memory (i.e. the SDRAM modules).This is sometimes referred to as a cold boot attack or ice-man attack.