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1. WELCOME

2. MIS – 104:
Computing
Fundamentals
BBA
Department of MIS
University of Dhaka

3. 3
Books
1.Introduction to Computer
Peter Norton
2. Computer Fundamentals
Dr. M Lutfar Rahman
3. Computer Fundamentals
Pradeep K. Sinha

4. 4
Previous class
>>Organization of computer
Input Unit
Output Unit
Memory unit
Control Unit
ALU

5. Today’s Class

6. Memory Unit

7. 7
Memory
Memory:
– One or more set of chips that stores data or
programmed instructions either temporarily or
permanently.
Classification of memory:
1. Primary memory
2. Secondary memory

8. 8
Location of different memories
ALU
MAIN MEMORY
OR
RESISTERS
CONTROL
UNITINPUT
UNIT
OUTPUT
UNIT
SECONDARY MEMORY

9. 9
Calculations of storage capacity
01 BYTE (B) 08 bit
01KB 1024 B
01 MB 1024.1024 B
01 GB 1024.1024.1024 B
01 TB 1024.1024.1024.1024 B

10. 10
Memory Terminologies
• Memory Address:
– Memory locations are
identified by numbers
100
B
X
Y
A
0000
0001
0002
FFFD
FFFE
FFFF

11. 11
Memory Terminologies
• Memory Word:
– When memory is read or written, a
block of bit is read or written instead of
a single bit.
– The block is considered to be a unit of
operation/processing
– A set of bit with which read/write
operation is done in a certain storage
device is called memory word
– Example: 08 bits or 01 Byte memory
word clearly 01000000 (08 bits)
represents 64 and its character is @;
here, this digital 08 bits in combine
known as a memory word
100
B
X
Y
A
0000
0001
0002
FFFD
FFFE
FFFF

12. 12
Memory Terminologies
• Destructive:
– composed of capacitors, data disappears when
read operation is done, needs re-write
operation to retain data
• Non-destructive:
– reverse nature
– Example: semiconductor, switch, flash
memory, pen drive

13. 13
Memory Terminologies
• Volatile:
– Type of memory where data remains only
when the power supply is on.
– Ex-RAM
• Non-volatile:
– here content remains even the power is turned
off
– Example: hard disk, floppy disk, flash drive etc

14. 14
Memory Terminologies:
Memory operation
• Memory store/write:
– The process of storing or writing data at the
specific location of the memory
– Data is stored as bits
– Ex- CD writing operation

15. 15
Memory Terminologies:
Memory operation
• Memory read:
– Also called ‘fetch operation’
– To read stored data or to process that stored
data
– A binary word is selected from a specific
address of memory and this is transferred to
another device
– Example: To hear a song from CD or any drive

16. 16
Memory Terminologies:
Memory access
• Random access:
– Any location of storage can be accessed at
any moment
– Does not matter whether the desired access
location is too close or a far away
– Consumes almost same amount of time
– Found in primary and secondary memory

17. 17
Memory Terminologies:
Memory access
• Sequential:
– accessing a bit of information in a serial order,
one after another
– Access time depends on the last
order/information execution time
– Example: Off line storage such as playing a
song from magnetic tape

18. 18
Primary memory
• Includes RAM & ROM
• CPU access directly on this memory
• Normally volatile in nature

19. 19
Primary memory: RAM
• Central storage unit
• Volatile
• Temporary in nature
• Holds operating systems, application
programme, data in current use
• Other name is (Read/Write) memory

20. 20
Different types of RAM
• S RAM- Exhibits data remanance but still
volatile as data dissolves when turn off
• D RAM- Data disappears after a certain
period automatically if it is not refreshed.
This type of RAM needs periodically re-
read or re-written. Ex- Z-RAM, TT-RAM,
A-RAM

21. 21
Primary memory: ROM
• Proportionally read operation is more than write
operation
• Contains user programmed instructions like
Bootstrap loader
• Non-volatile
• permanent

22. 22
Different types of ROM
ROM
Mask ROM PROM EPROM EEPROM

23. 23
Secondary memory
• Auxiliary unit
• Storing capacity is huge
• Normally non-volatile
• Normally two types-
1. Magnetic
2. Optical

24. 24
Secondary memory: Magnetic
• Variation of ‘Magnet polarity’ determines
whether the bit will be 0 or 1
• Data write process is done by
electromagnetic head
• Ex- hard disk, floppy disk, magnetic tape

25. 25
Secondary memory: Optical
• Variation of light reflection determines the
nature of bits
• Data is written with the help of LASER or
UV rays
• Ex-CD-R/RW, DVD-R/RW, BD-R

26. 26
Memory address:
• It is a number or a set of digital number
(bit/Bytes) in the memory
• This address specially represented by
binary numbers
• Decimal, Octal, Hex-decimal numbers are
also used for addressing

27. 27
Virtual memory:
• When secondary memory is used as primary
memory then this is called virtual
• Provide assistance to the RAM, by creating
space for the great amount of data
• When RAM finishes it’s access, virtual memory
vanishes
• Virtual memory can be selected by user

28. 28
Cache memory:
• Small memory chip is attached between
CPU & main memory
• Give the assistance to the resisters
• Speed up the data process
• Three types of cache memory is found e.g.
L1(CPU resident), L2 & L3 (mother board)

29. 29
Resisters
• They are not the part of main memory but
store data and pass as directed by CPU
• The size of the resisters which is
sometimes called the word size,indicates
the amount of data with which CPU can
work/access.
• Ex- 32 bits processor means, 04 bytes
data processing capability

30. Question...???