memory ppt111

8/3/2019 Memory PPT111

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Memory Hierarchy II


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Memory Types

RAM (Random access memory): SRAM (Static RAM) (flip-flop gates) DRAM (Dynamic RAM)

ROM (Read only memory) PROM (programmable) EPROM (erasable programmable) EEPROM (electronically erasable

programmable)


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RAM

Static RAM Dynamic RAM


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Memory Slots

SIMM slot used in macintosh computermotherboard used during the 1980s and

1990s 30-pin and 72-pin DIMM Slot used in desktop computer DDR and SDRAM nowadays used in

desktop RIMM slot released for i820 chipset, 72 ins available


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Static RAM

Made by Flip-flop (referring to anelectronic circuit can be used to store stateinformation ON or OFF )

No refresh Rate (No need to refresh ) Faster than Dynamic RAM

High cost Ex: Cache Memory


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Dynamic RAM Made by Capacitor (stores energy and produces

a mechanical force between the conductor,Capacitors are widely used in electronic circuits

for blocking direct current while allowingalternating current to pass ) Need to Refresh Cost is Low Slow compare to Static Ex: SDRAM,DDR
http://en.wikipedia.org/wiki/Energyhttp://en.wikipedia.org/wiki/Direct_currenthttp://en.wikipedia.org/wiki/Alternating_currenthttp://en.wikipedia.org/wiki/Alternating_currenthttp://en.wikipedia.org/wiki/Direct_currenthttp://en.wikipedia.org/wiki/Energy


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DDR

Dual Data Rate (Or) Double Data Rate It is Latest RAM type

This is used for Speed capabilities Type DDR1, DDR2, DDR3


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DDR1

2.5v No of Occurrence 200 MHz

64 bits data bus used Delay time is 2.5nano Sec Data Transfer Speed is 400Mbps

184 pin


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DDR2

1.8 v Bus Frequency (no of Occurrence) 333

MHz 64 bits Data Bus is Used (comp-mem) Delay time 5ns(nano second)

240,204 pin


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DDR3

1.5 v Bus Frequency (no of Occurrence) 666

MHz 64 bits Data Bus is Used (comp-mem) CAS latency ( Delay time ) 7 per ns

240 pin


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SDRAM

Synchronous Dynamic Random AccessMemory

MIN Frequency 133 MHz MAX Frequency 266 MHz 168 pin

3 pieces or 2 notch keys


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ROM

Read Only Memory Non volatile Memory

Data is not erased Type PROM, EP-ROM, EEP-ROM, Flash ROM


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P-ROM

Programmable ROM Invented in 1956

Stored the Data by 0, 1 The bit cell is programmed by applying ahigh-voltage pulse


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EP-ROM Erasable Programmable ROM Non volatile (hold the data when power

off) Data is erased by ultraviolet light address represented by the values at the

address pins of the EPROM Storing data in the memory requires

selecting a given address and applying ahigher voltage to the transistors


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EEP-ROM

Electrical Erasable Programmable ROM Types of Non-volatile Memory

It is same as Flash memory. that can be erased and reprogrammed inunits of memory called blocks

Store small amounts of data when poweris removed


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SEQUENTIAL ACCESS STORAGEDEVICES AND MEDIA (SASD) magnetic tape

DIRECT ACCESS STORAGE DEVICESAND MEDIA (DASD) magnetic floppy disks

magnetic hard disks optical discs

Secondary Memory


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magnetic hard and floppy disks removable hard disks optical discs

CD-ROM, CD-R, CD-RW, DVD

GEOMETRY:TRACKS and SECTORS

Direct Access Storage Devices


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SEEK controlleradvances read/writehead to proper track

LATENCY

waitsfor proper sector to

rotate under head READ/WRITE disk

head scans the sectorfor read or write

Direct Access


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FLOPPY DISKS 5.25 and 3.5 inch

diskettes 1.44 2.88 MBytes

capacity access: drive speeds

600 r.p.m. inexpensive, archival

uses for smallamounts of data

HARD DISKS 3.5 inch has approx

10-30K tracks perside multiple disk, sides

(cylinders)

high capacity access: drive speeds

5,400; 7,200 r.p.m.and higher

Magnetic Disks


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CD-ROM

1. density : 16,000 tpi2. Size : up to 650 Mbytes3. Type :

a. CD-R( discs are burnt one ata time)

b. CD-RW ( Erased, written up to1,000 times)


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Table 5.2 CD-ROM speeds

Speed ------------1x2x4x6x8x

12x16x24x32x40x

Data Rate ------------------------153,600 bytes per second307,200 bytes per second614,400 bytes per second921,600 bytes per second1,228,800 bytes per second1,843,200 bytes per second2,457,600 bytes per second3,688,400 bytes per second4,915,200 bytes per second6,144,000 bytes per second

Approximation ------------150 KB/s300 KB/s600 KB/s900 KB/s1.2 MB/s1.8 MB/s2.4 MB/s3.6 MB/s4.8 MB/s6 MB/s


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DVD

Digital Versatile Disc second generation CD-ROM higher capacity:

higher data density multiple sides multiple layers

Double side Maximum size 17 GB low 4.7 GB


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Figure 5 4


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Figure 5-4

Memory hierarchy


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Register

A register is a very small amount of veryfast memory that is built into the CPU(central processing unit) in order tospeed up its operations by providingquick access to commonly usedvalues.
http://www.linfo.org/memory.htmlhttp://www.linfo.org/memory.html


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It is a fastest memory In built in CPU(L1,L2)

L1(Primary cache

first check data incache memory it is equalant access timeto CPU clock speed)

L2(secondary cache

Figure 5-5


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Figure 5 5

Cache


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MAIN MEMORY

5.2

Figure 5-6


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Figure 5 6

Physical layout of a magnetic disk

Figure 5-14


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Figure 5 14

Connecting CPU and memory using three buses


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Other Type of RAM NVRAM (does not lose its information when power is

turned off ) The best-known form of NVRAM memorytoday is flash memory (electrically erased andreprogrammed )

EDORAMEDO (extended data output) RAM is a type ofrandom access memory ( RAM) chip that improves thetime to read from memory on faster microprocessor ssuch as the Intel Pentium . EDO RAM was initiallyoptimized for the 66 MHz Pentium. For faster computers,

different types of synchronous dynamic RAM ( SDRAM )are recommended. GRAM
http://en.wikipedia.org/wiki/Flash_memoryhttp://searchmobilecomputing.techtarget.com/sDefinition/0,,sid40_gci214255,00.htmlhttp://searchcio-midmarket.techtarget.com/sDefinition/0,,sid183_gci212568,00.htmlhttp://searchcio-midmarket.techtarget.com/sDefinition/0,,sid183_gci212771,00.htmlhttp://searchcio-midmarket.techtarget.com/sDefinition/0,,sid183_gci214193,00.htmlhttp://searchcio-midmarket.techtarget.com/sDefinition/0,,sid183_gci214193,00.htmlhttp://searchcio-midmarket.techtarget.com/sDefinition/0,,sid183_gci212771,00.htmlhttp://searchcio-midmarket.techtarget.com/sDefinition/0,,sid183_gci212568,00.htmlhttp://searchmobilecomputing.techtarget.com/sDefinition/0,,sid40_gci214255,00.htmlhttp://en.wikipedia.org/wiki/Flash_memory

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