(1)Types of memory
Memory can be categorized by the method used to store data. Several
methods of data storage are summarized below.
Reference
RAM
DRAM
Abbreviation for “Random Access
Memory.”
RAM
SRAM
Reference
ROM
Memory
Abbreviation for “Read Only Memory.”
Mask ROM
Reference
DRAM
ROM
Abbreviation for “Dynamic Random Access Memory.”
EPROM
EEPROM
Reference
SRAM
Abbreviation for “Static Random-Access
Memory.”
Reference
EPROM
●RAM (Random Access Memory)
“RAM” is a volatile type of memory in which stored content is lost when
the power is turned off. Data can be read and written, and is used as main
memory or cache memory.
Abbreviation for “Erasable Programmable Read Only Memory.”
DRAM
SRAM
Capacity
Large
Small
Processing speed
Slow
Fast
EEPROM
Cost
Low
High
Abbreviation for “Electrically Erasable
Programmable Read Only Memory.”
Refresh function (re-supply of electricity)
Available
Not available
High
Low
Reference
Reference
Flash memory
“Flash memory” is a type of EEPROM
that is electrically rewriteable. For computers, flash memory is used as storage
for the BIOS or as auxiliary storage device.
Comparison item
Power consumption
●ROM (Read Only Memory)
“ROM” is a non-volatile type of memory that retains stored content after
the power is turned off. There are read-only ROMs for data and programs,
and rewriteable ROMs used as flash memory or storage for the computer
BIOS.
Type
Mask ROM
Data is written at the manufacturing stage and cannot be rewritten
afterwards.
EPROM
Data can be written afterwards. Data can be erased using ultraviolet
light.
EEPROM
EPROM that can erase data electrically. Flash memory is a typical
type of EPROM that is used in digital cameras and IC cards.
Reference
BIOS
“BIOS” is a program that controls the
input/output between the computer unit
and peripheral devices.
BIOS is stored in ROM and integrated
into the motherboard.
Abbreviation for “Basic Input/Output
System.”
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Characteristics