Temporary electronic storage for data
and instructions, utilizing electronic
impulses on a chip.
(i) A unit of a computer that stores
data for retrieval.
(ii) Capacity for retaining information:
four gigabytes of memory.
(i) A part of a computer in which data
is stored for later use.
(ii) The capacity of a computer, chips,
and storage devices to preserve data and
programs for retrieval. Memory is measured
Internal storage areas in the computer.
The term memory identifies data storage
that comes in the form of chips, and the
word storage is utilized for memory that
exists on tapes or disks. Additionally, the
term memory is usually used as a shorthand
for physical memory, which refers to the
actual chips capable of storing data.
Some computers also use virtual memory,
which expands physical memory onto a hard
disk. Every computer comes with a certain
amount of physical memory, usually referred
to as main memory or RAM. One can think of
main memory as an array of boxes, each of
which can contain a single byte of information.
A computer that has 1 megabyte of memory,
therefore, can store about 1 million bytes
(or characters) of information.
Different types of memory:
RAM (Random-Access Memory)
This is the same as main memory.
When used by itself, the term RAM refers
to read and write memory; that is, one
can both write data into RAM and read
data from RAM. This is in opposition to ROM,
which permits one only to read data.
Most RAM is volatile, which means that it
needs a steady flow of electricity to
maintain its contents. As soon as the power
is turned off, whatever data was in RAM is lost.
ROM (Read-Only Memory)
Computers almost always contain a small
amount of read-only memory that stores instructions
for starting up the computer. Unlike RAM, ROM cannot
be written to.
PROM (Programmable Read-only Memory)
A PROM is a memory chip on which one can
retain a program. But once the PROM has been used,
one cannot wipe it clean and use it to store
something else. Like ROMs, PROMs are non-volatile.
EPROM (Erasable Programmable Read-only Memory)
An EPROM is a special type of PROM that can
be erased by exposing it to ultraviolet light.
EEPROM (Electrically Erasable Programmable Read-only Memory)
An EEPROM is a special type of PROM that
can be erased by exposing it to an electrical