The document discusses the functions and types of computer memory. It describes memory as a device that stores data and programs, and notes its functions include keeping information for processing and storing results temporarily. The document outlines the memory hierarchy including primary memory (RAM, ROM) and secondary memory (hard disks, tapes, etc.). It differentiates types of RAM and ROM, and describes cache memory.

1. Functions of Memory
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2. Objective:
On completion of this period, you would be able to
learn
 Functions of memory.
 Types of memory.
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3. 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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4. Prerequisites:
What is a memory?
Memory is a device that stores computer’s data
& programs.
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5. Memory hierarchies
Primary Secondary
Registers
Memory Memory
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6. 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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7. 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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8. Units of measure for computer memory
Unit Abbrevia- Approximate Actual Value
tion Value (Bytes) (Bytes)
Kilobyte KB 1,000 1,024
Megabyte MB 1,000,000 1,048,576
(1 million)
Gigabyte GB 1,000,000,000 1,073,741,824
(1 billion)
Terabyte TB 1,000,000,000,000 1,099,511,627,776
(1 trillion)
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9. Types of memory
MEMORY
MEMORY
PRIMARY MEMORY
PRIMARY MEMORY SECONDARY MEMORY
SECONDARY MEMORY
(INTERNAL MEMORY)
(INTERNAL MEMORY) (EXTERNAL MEMORY)
(EXTERNAL MEMORY)
CPU
CPU
MAGNETIC MAGNETIC
MAGNETIC MAGNETIC OPTICAL
OPTICAL
ON CHIP TAPE
TAPE DISK
REGISTER ON CHIP DISK DISK
DISK
REGISTER CACHE
CACHE
RAM ROM
ROM
RAM
DRAM SRAM PROM
PROM EPROM
EPROM EEPROM
DRAM SRAM EEPROM
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10. 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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11. 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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12. Random Access Memory
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13. Types of RAM
1. DRAM (Dynamic RAM)
2. SRAM (Static RAM)
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14. 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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15. 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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16. 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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17. 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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18. 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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19. Cache memory
 Placed between the CPU and the main memory.
 It increases the speed of the computer up to 15%.
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20. 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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21. 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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22. 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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23. 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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24. 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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25. Secondary Memory - Examples
 Magnetic tape
 Magnetic disk
 Optical disk
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26. Summary:
In this class, we have learnt about
 Functions of memory.
Types of memory used in computers.
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27. Questions
 Explain the types of memory devices used?
 List the differences between RAM & ROM.
 Explain the functions of memory?
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28. Quiz:
1. Is RAM a volatile memory?
a. Yes
b. No
Answer: a
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29. Quiz:
2. ROM is a
a. Volatile
b. Non-volatile
c. both a & c
Answer: b
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30. Quiz:
3. The data stored in memory is in
a. Decimal form
b. Hexadecimal form
c. Binary form
d. Octal form
Answer: c
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