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© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved. 6-3 Quiz03 Next Lecture – (Lecture #13) Contents: Chapter 4 – The System Unit Lecture Slides- #10 - #12
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66CH
APT
ER
THE SYSTEM UNIT
6-2
© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved.
Competencies
Details about memoryMemory Classification BasesCache MemoryVirtual Memory
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© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved.
Quiz03
Next Lecture – (Lecture #13)Contents:
Chapter 4 – The System UnitLecture Slides- #10 - #12
6-4
© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved.
Memory Classification Bases
Reading/ Writing CapabilityRead Only MemoryRead/ Write Memory
Data Access MechanismSequential Access MemoryRandom Access Memory
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© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved.
… Memory Classification Bases
Volatility of Data No Data Loss without Electricity (Non-volatile Memory)Data loses without electricity (Volatile Memory)Data can be changed and be permanently saved once changed (CMOS Memory)
Speed of AccessCache Memory (Very high accessing speed)
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© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved.
Memory
Holding area for data, instructions, and information Types of memory chips
RAM – holds programs and data
ROM – fixed start-up instructions
CMOS – flexible start-up instructions
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© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved.
RAM
Random Access MemoryPrimary Memory of a computerData and Program needs to be loaded for processingAny memory location can be accessed randomlyVolatile storage Uses Cache support for increased efficiencyFlash RAM – Non-volatile/ portable
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© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved.
ROM
Read-only memoryFirmwareCannot be changed by the userStart-up instructions, keyboard control capabilities
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© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved.
CMOS
Complementary metal-oxide semiconductorFlexible and expandableStartup informationNon-volatileIts contents may be updated
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© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved.
….The Memory (More Concepts)
Virtual MemoryA technique used to make huge programs run on small memory size computersA huge program is divided into many portionsEach portion could be adjusted inside the RAMProgram is then run by loading only the needed portion from hard diskOperating System (OS-win98) is the one who is taking care of this transparently.Effect: The program runs slowly
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© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved.
… The Memory (More Concepts)
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© 2005 The McGraw-Hill Companies, Inc. All Rights Reserved.
Memory Capacity
UnitUnit CapacityCapacityMegabyte (MB) 1 billion bytes
Gigabyte (GB) 1 million bytes
Terabyte (TB) 1 trillion bytes