Electronic storage technology includes what is commonly called RAM (Random
Access Memory) . RAM is used to hold the operating system, data and application
programs currently needed to complete tasks, enabling the computer's Central
Processing System (CPU) to access information stored in memory quickly. When
a command is entered from the keyboard, the CPU interprets the command and
instructs the hard drive to load the command into RAM, where it is more accessible.
RAM is faster to write to and read from than any other type of storage in
a computer (including the floppy disk, hard disk, and CD-ROM).
RAM is called "random access" because any storage location on
the computer can be accessed directly. It is organized in a way that enables
information to be stored and accessed directly to specific locations.
RAM is small in size and in the amount of data it can hold. It can be compared
to short-term memory, focusing on the work at hand. When there is not enough
room in memory for all the data needed by the CPU, the computer has to create
a virtual memory file. This is the equivalent of simulating additional RAM,
a process called "swapping". On average, the CPU is 60,000 times
slower in accessing the hard drive than in accessing RAM.
Generally, the more memory a computer system has, the better its performance.
A typical computer could come with 32 million bytes of RAM and a hard drive
than can hold around 4 billion bytes. Most computers are designed to allow
for additional RAM to be added. The more memory your computer has the faster
applications run, and the easier it is to run several programs at once.
RAM can be divided into main RAM and video RAM. Main RAM stores every kind
of data and makes it easily accessible to microprocessor, while video RAM
stores data for your display screen so images can get to your display quickly.
Main RAM includes dynamic and static RAM. Dynamic RAM (DRAM) is the least
expensive type of RAM and requires frequent power refreshing after each read
in order to keep the charge that holds its content in place. DRAM includes:
Fast Page Mode DRAM, Enhanced DRAM, Extended Data Output RAM or DRAM, Double
Data Rate SDRAM, Direct Rambus DRAM, Burst Extended Data Output DRAM, Synchronous
DRAM, Nonvolatile RAM, Enhanced SDRAM, Ferroelectric RAM, PC100 SDRAM, and
JEDEC SDRAM. Static RAM (SRAM) is more expensive but does not need to be
refreshed after each read, so it is quicker to access. However, SRAM requires
four times more space than DRAM. Burst SRAM is synchronized with the system
clock to make it more easily synchronized with anything that accesses it,
in order to speed up waiting time.
Video RAM is basically just all RAM used to store image information for
the display monitor. All kinds of video RAM are arrangements of dynamic RAM.
Images are first read by the processor and then written to video RAM. From
here, the data is converted by a RAM digital-to-analog converter into signals
that are sent to the display presentation mechanism. Video RAM consists of
RAMDAC (Random Access Memory digital-to-analog converter), Window RAM, Rambus
Dynamic RAM, Synchronous Graphics RAM, Multibank Dynamic RAM, and Video RAM
(the most common type).
Flash memory (also called flash RAM) is a type of memory that can be deleted
and reprogrammed into units of memory called blocks. While flash memory is
not as useful as random access memory, it can be helpful in holding control
codes in order to make them easier to update and change. The name "flash
memory" is used because on the microchip, a section of memory cells
are erased in a "flash". Flash memory is used not only in computers,
but in digital cameras, cellular phones, and other devices.
