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8/4/2019 Non Volatile Memory1
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Introduction Non-volatile memory is computer memory that
can retain the stored information even thesystem is not powered.
It is typically used for the task of secondarystorage, or long-term persistent storage.
It either costs more or performs worse thanvolatile random access memory.
IBM is currently developing MRAM (Magnetoresistive RAM)
Its data storage, classified as, electricallyaddressed and mechanically addressedsystems.
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Types of Non VolatileMemory
ROM
FLASHMEMORY
EEPROMPROM
PROM
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ROMRead only Memory
Permanently or semi-permanently holdsdata
Special program required to write data Ideal place to put the computer’s start-up
instruction
3 types of ROM:PROMEPROMEEPROM
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PROMProgrammable Read Only Memory
Originally contained silicon or metalfuses which would be blown in orderto change 0s and 1s.
Once the bits are changed, theycannot be restored
Widely used in consumer andautomotive electronics, RFID, HDMI
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EPROMErasable Programmable Read Only Memory
Invented by Engineer Dov Frohman
Can hold data from 10-20 years
Erasing EPROM ProgrammingErasure is accomplished by using UV light
UV light belongs to UVC range
Frequency of 253.7
Shouldn’t remain under EPROM erasure for toolong, may lead to “over-erasure”
Over-charging of UV light makes the EPROM’s
floating gates unstable
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TYPES OF EPROM
UV Erase EPROM OTP EPROM
Data erased by UV light
To remove charge,place chip under UV lampfor 20-30 minutes
Its electrically anEPROM, but with aquartz windowmissing
First 2716 EPROMlaunched in October
1977 in Texas
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EEPROMElectrically Erasable Programmable Read-Only Memory
The only user-modifiable ROM that can be erased& reprogrammed
EEPROM IC SERIAL, 32K x 8 64K chip
HISTORY Designed by George Perlegos at Intel
Seeq Technology designed 1st
fully functionalEEPROM
To configure an EEPROM chip, an electric fieldproduced by the charge pump is applied locally
to cells marked for modification.
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EEPROM EEPROM Structure
Physically similar to EPROM but also composedof cells with two transistors
Floating gate - separated from the control gate by athin oxide layer
Insulating layer - around 1nanometer voltagerequirements to initiate changes in cell
Floating gate and control gate’s bit value is from 1-0
LimitationsCan be re-programmed but only limited times
Hence, used as computer’s BIOS code
Modern day EEPROM can be rewritten upto amillion times
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FLASH MEMORY A type of constantly powered non-volatile memory that can
be erased and reprogrammed
A close relative to EEPROM
Information stored in cells in the chip
Data gets erased off in a flash
Advantages (over traditional hard-drive) Non-volatile
Smaller in size
Highly portable Faster Access Time
Low Price & High Capacity
Maintains Storage even
without Power Supply
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FLASH MEMORY Uses
Digital Cellular Phones
Digital Cameras
LAN switches
PC Cards for Notebooks Digital Set-top Boxes
Your Computer’s BIOS
Memory Sticks
Video Game Cards
Modems
MP3 Players
Pen Drives
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Summary From all of these, we conclude that non volatile
memory has 5 basic types which have helped instoring data, using effective techniques evenwhen there is no power supply connected to the
storage device
We still have the hope that non-volatile memorymay one day eliminate the need for
comparatively slow forms of secondary storagesystems, which include hard disks.
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