Information Technology Reference
In-Depth Information
Understanding Memory
Like the memory in the human brain, computer memory stores data.
Also like human memory, there is both short-term (temporary) and
long-term (permanent) memory storage. Some memory is dynamic,
in that it stores data only until the computer is turned off.
Dynamic
memory
(also called volatile memory) must be constantly refreshed.
Static memory
(also called non-volatile memory) retains whatever you
put in it indefinitely.
dynamic memory
Memory that does not
retain its data unless it is constantly electrically
refreshed.
static memory
Memory that retains its data
without electricity being constantly applied.
Another way to classify memory is whether it can be overwritten with
new data or not.
Random Access Memory (RAM)
can be rewritten
freely;
Read-Only Memory (ROM)
cannot (at least not in the same
way that RAM can; see the following Note). All ROM is static, but RAM
can be either dynamic (more common) or static.
Random Access Memory (RAM)
Memory
that can have its values changed freely, an unlim-
ited number of times.
Read-Only Memory (ROM)
In general,
memory that cannot be rewritten. However, there
are exceptions to that in newer types of ROM.
How Computers Use Memory
Computers use different types of memory in various ways. Here are some
of the most common memory uses:
◾
System memory:
The main memory in a computer
system, such as the RAM installed on the PC's
motherboard, is dynamic RAM (DRAM). System
memory is installed in slots on the motherboard,
perpendicular to the motherboard itself.
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System memory
◾
Component memory:
Many components have a
small amount of memory built in for their own use.
For example, a printer might have RAM that holds
the information about the page it is printing, and
a display adapter might have memory to hold the
data about the image it is displaying on the monitor.
Component memory is typically DRAM unless the
component's function requires it to be otherwise
because that's the least expensive kind.
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Component memory
