function of memory.4to5
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TRANSCRIPT
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Functions of Memory
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Objective:
On completion of this period, you would be able to learn
Functions of memory.
Types of memory.
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Recap
Blocks in CPU
Control unit & Arithmetic and Logical Unit.
Functions of CPU
Performs calculations, takes decisions, and controls all the units.
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Prerequisites:
What is a memory?
Memory is a device that stores computer’s data & programs.
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Memory hierarchies
Registers PrimaryMemory
SecondaryMemory
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Memory (Contd..)
A space to keep computer’s data.
It stores program, data results or any kind of information.
Memory stores binary information i.e. 0’s and 1’s.
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Memory (contd)
Place where results get stored prior to the output Memory is measured in bytes One byte of memory is needed to store a
character
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Units of measure for computer memory
Unit Abbrevia-tion
ApproximateValue (Bytes)
Actual Value(Bytes)
Kilobyte KB 1,000 1,024
Megabyte MB 1,000,000(1 million)
1,048,576
Gigabyte GB 1,000,000,000(1 billion)
1,073,741,824
Terabyte TB 1,000,000,000,000(1 trillion)
1,099,511,627,776
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Types of memory
MEMORYMEMORY
PRIMARY MEMORY(INTERNAL MEMORY)
PRIMARY MEMORY(INTERNAL MEMORY)
SECONDARY MEMORY(EXTERNAL MEMORY)
SECONDARY MEMORY(EXTERNAL MEMORY)
CPUCPU
REGISTERREGISTER ON CHIPCACHE
ON CHIPCACHE
MAGNETICTAPE
MAGNETICTAPE MAGNETIC
DISK
MAGNETICDISK
OPTICALDISK
OPTICALDISK
RAMRAM ROMROM
DRAMDRAMSRAMSRAM PROMPROM EPROMEPROM
EEPROMEEPROM
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Random Access Memory (RAM)
It is volatile memory i.e. temporary memory.
Performs read and write operations.
Usually hidden to users.
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RAM (Contd..)
It exists as a chip on the motherboard near the CPU.
RAM stores data and programs while they are being used.
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Random Access Memory
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Types of RAM
1. DRAM (Dynamic RAM)
2. SRAM (Static RAM)
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Dynamic RAM
Dynamic RAM loses its stored information in a very short time even though the power supply is on.
Only one transistor is needed to form a memory cell and result in high packing density and moderate speed.
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Dynamic RAM (Contd...)
Consume less power.
Used where large capacity of memory is needed.
Dynamic RAM being cheaper is used for main memory.
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Static RAM
Static RAM retain stored information only as long as power supply is on.
Static RAMs are costlier and consume more power.
Static RAM being faster is used in cache memory.
Static RAMs hold information in flip-flop consisting of two cross coupled inverters.
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Read Only Memory (ROM)
It is non volatile memory .i.e. permanent storage.
Performs only read operations.
Hidden to users.
used to store routine & fixed programs, during the booting process.
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Types of ROM
1. PROM - (Programmable Read Only Memory)
2. EPROM - (Erasable Programmable Read Only Memory)
3. EEPROM - (Electrically Erasable PROM)
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Cache memory
Placed between the CPU and the main memory.
It increases the speed of the computer up to 15%.
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Cache memory (contd)
It is not accessible to users i.e. information cannot be written into cache memory by users.
It stores instructions and data which are to be immediately executed.
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Primary memory
The storage is temporary.
Data stored in it lost when power supply is cut off.
Storage capacity is limited.
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Primary memory (contd)
Known as Main Memory or Internal Memory
It is a part of CPU
Used for storing a little volume of data at the time of processing
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Secondary memory
The storage is permanent.
The data stored in it does not get erased when the power is switched off.
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Secondary memory (contd)
Known as External Memory or Auxiliary Memory
Storage capacity is unlimited
Used to store large volumes of data permanently
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Secondary Memory - Examples
Magnetic tape
Magnetic disk
Optical disk
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Summary:
In this class, we have learnt about
Functions of memory.
Types of memory used in computers.
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Questions
Explain the types of memory devices used?
List the differences between RAM & ROM.
Explain the functions of memory?
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Quiz:
1. Is RAM a volatile memory?
a. Yes
b. No
Answer: a
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Quiz:
2. ROM is a
a. Volatile
b. Non-volatile
c. both a & c
Answer: b
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Quiz:
3. The data stored in memory is in
a. Decimal form
b. Hexadecimal form
c. Binary form
d. Octal form
Answer: c