Pronounced
ramm, acronym for
random
access memory, a type of
computer memory that can be
accessed randomly; that is, any
byte of memory can be accessed without
touching the preceding bytes. RAM is the most common type of memory found in
computers and other
devices, such as
printers.
There are two different types of RAM: DRAM (Dynamic
Random Access Memory) and SRAM (Static Random Access
Memory). The two types differ in the technology they use to hold data, with
DRAM being the more common type. In terms of speed, SRAM is faster. DRAM needs
to be refreshed thousands of times per second while SRAM does not need to be
refreshed, which is what makes it faster than DRAM. DRAM supports access times
of about 60 nanoseconds, SRAM can give access times as low as 10 nanoseconds.
Despite SRAM being faster, it's not as commonly used as DRAM because it's so
much more expensive. Both types of RAM are volatile, meaning that they
lose their contents when the power is turned off.
In common usage, the term RAM is synonymous with
main memory, the
memory available to programs. For example,
a computer with 8MB RAM has approximately 8 million bytes of memory that programs
can use. In contrast, ROM (read-only
memory) refers to special memory used to
store programs that boot the computer and
perform diagnostics. Most personal
computers have a small amount of ROM (a few thousand bytes). In fact, both
types of memory (ROM and RAM) allow
random access. To be precise, therefore, RAM should be referred to as
read/write RAM and ROM as
read-only RAM.
See the "DRAM
Memory Guide" in the
Quick Reference section of Webopedia. This Webopedia Quick Reference offers
general information on the two types of RAM and provide an overview on the
common modules of each type.
See "Tips
to Fix a Slow Running Computer" in the
Quick Reference section
of Webopedia.
