Computer memoryComputer memory

ContentContent

1.1. Classification of memory by priorityClassification of memory by priority

2.2. Classification of memory by accessClassification of memory by access

3.3. Division of Read-Only MemoryDivision of Read-Only Memory

4.4. Division of Read-Write MemoryDivision of Read-Write Memory

5.5. Read-Only Memory types in more detailsRead-Only Memory types in more details

6.6. VolatilityVolatility

7.7. Read-Write Memory types in more detailsRead-Write Memory types in more details

8.8. SourcesSources

Classification by priorityClassification by priority a) primary - storage of intermediate dataa) primary - storage of intermediate data - necessary to run the computer- necessary to run the computer

- RAM, Cache- RAM, Cache

b) secondary - long-term storage of datab) secondary - long-term storage of data - HDD- HDD

c) tertiary - CD, DVD, memory card...c) tertiary - CD, DVD, memory card...

d) off-line - disconnected storaged) off-line - disconnected storage - unplugged USB flash drive, - unplugged USB flash drive,

external HDDexternal HDD

Classification by accessClassification by access

Read-Only Memory Read-Write Memory

Read-Only MemoryRead-Only Memory

MROM PROM EPROM EEPROM Flash

Read-Write MemoryRead-Write Memory

DAM SAM CAM

SRAM DRAM

SIMM DIMM DDR DDR2 DDR3

RAM

MROMMROM

MROM (Mask Read-Only Memory)MROM (Mask Read-Only Memory) its content is programmed by its content is programmed by

manufacturer not by usermanufacturer not by user then we can use it only for readingthen we can use it only for reading the oldest type of ROMthe oldest type of ROM

PROMPROM

PROM (Programmable Read-Only Memory)PROM (Programmable Read-Only Memory) it is blank from the manufacturerit is blank from the manufacturer can be programmed just once by the usercan be programmed just once by the user

EPROMEPROM

EPROM (Erasable Programmable EPROM (Erasable Programmable Read-Only Memory)Read-Only Memory)

can be erased by UV lightcan be erased by UV light recognizable by the transparent recognizable by the transparent

window in the topwindow in the top

EEPROMEEPROM

EEPROM (Electrically Erasable EEPROM (Electrically Erasable Programmable Read-Only Memory)Programmable Read-Only Memory)

can be programmed and erased can be programmed and erased electricallyelectrically

while erasing whole content is erasedwhile erasing whole content is erased

Flash memoryFlash memory

used in memory cards or USB flash drives used in memory cards or USB flash drives specific type of EEPROMspecific type of EEPROM erased and programmed in larger blockserased and programmed in larger blocks faster than old EEPROMfaster than old EEPROM

VolatilityVolatility

non-volatile - stores the information non-volatile - stores the information even even without power supply without power supply

- all mentioned types so far- all mentioned types so far

volatile - requires constant power to volatile - requires constant power to maintain maintain the stored informationthe stored information

- following types from here- following types from here

Read-Write MemoryRead-Write Memory

DAM (Direct Access Memory)DAM (Direct Access Memory) - direct access to all memory cells- direct access to all memory cells - RAM- RAM

SAM (Sequential Access Memory)SAM (Sequential Access Memory) - data reading in sequence - data reading in sequence - HDD, optical discs- HDD, optical discs

CAM (Content Addressable Memory)CAM (Content Addressable Memory) - associative memory- associative memory - returns value according to supplied - returns value according to supplied

wordword

RAMRAM RAM (Random Access Memory)RAM (Random Access Memory)

- any piece of data can be - any piece of data can be returned in a returned in a constant time constant time

SRAM (Static Random Access Memory)- does not need to be periodically

refreshed- more complex internal structure,

more expensive, less capacity than DRAMDRAM (Dynamic Random Access Memory)

- to keep information must be periodically refreshed

- structural simplicity, high capacity

SIMMSIMM

SIMMSIMM ( (SSingle ingle IIn-line n-line MMemory emory MModule)odule) is a type of memory module from the is a type of memory module from the

early 1980s to the late 1990searly 1980s to the late 1990s

DIMMDIMM

DIMM (DDIMM (Dual ual IIn-line n-line MMemory emory MModuleodule)) designed for use in personal designed for use in personal

computers, computers, workstations workstations and and serversservers ccompatible with 64-bit Intel Pentiumompatible with 64-bit Intel Pentium

DDRDDR

DDR (DDR (Double Data RateDouble Data Rate)) used in personal computer, notebooksused in personal computer, notebooks dual-channeldual-channel configuration configuration

DDR2DDR2

DDR (Double Data Rate)DDR (Double Data Rate) supersedes DDR RAM which are not supersedes DDR RAM which are not

compatible with DDR2compatible with DDR2 the data bus can be run at twice the the data bus can be run at twice the

speed of the memory clockspeed of the memory clock

DDR3DDR3

DDR (Double Data Rate)DDR (Double Data Rate) is an improvement over its predecessor is an improvement over its predecessor

DDR2DDR2 no backward no backward compatibcompatibilityility

SourcesSources

notes fromnotes from the the grammar schoolgrammar school wikipedia.orgwikipedia.org

Thank you for attentionThank you for attention