02 Chapter 2 Data representation and organization of computer system_V4 (2).pptx

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NATIONAL ECONOMICS UNIVERSITY
NEU COLLEGE OF TECHNOLOGY
FACULTY OF INFORMATION TECHNOLOGY
INTRODUCTIONTO INFORMATIONTECHNOLOGY
CHAPTER II. INFORMATION REPRESENTAITON
AND COMPUTER ORGANIZATION

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LECTURER
MSC. PHAMTHAO
Senior Lecture
📞 0966 986 689
📩 thaop@neu.edu.vn
https://fit.neu.edu.vn/lecturer/th-s-pham-thao

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CHAPTER II. INFORMATION REPRESENTAITON AND COMPUTER
ORGANIZATION
https://fit.neu.edu.vn/syllabus/K66/en/EP17.CNTT1116
• 2.1.1 Number Systems
• 2.1.2 Data Encoding in Computers
• 2.1.3 Logical Operations with Binary Numbers
• 2.1.4 Integer Representation
• 2.1.5 Floating-Point Number Representation
• 2.1.6 Character Representation
• 2.1.7 Audio and Image Representation
2.1. Data Representation on Electronic Computers
• 2.2.1 Basic Computer Model
• 2.2.2 Central Processing Unit (CPU)
• 2.2.3 Memory
• 2.2.4 Input-Output Systems
• 2.2.5 System Interconnection (Buses)
• 2.2.6 Peripheral Devices
2.2 Organization of Computer Systems

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2.1. DATA REPRESENTATION ON ELECTRONIC COMPUTERS
2.1.1. Number Systems
• Decimal System
• Base-r Number System
• Binary System
• Octal System
• Hexadecimal System
• Conversion between Number Systems
2.1.2 Data Encoding in
Computers
• Overview
• Information Units
2.1.3. Logical Operations with
Binary Numbers
• Arithmetic Operations with Binary Numbers
• Logical Operations with Binary Numbers
2.1.4. Integer Representation
• Unsigned Integers
• Signed Integers
• Performing Arithmetic Operations with Integers
2.1.5. Floating-Point
Representation
• Overview
• IEEE754/85 Standard
2.1.6. Character
Representation
• Overview
• ASCII Code
• Unicode Code
2.1.7. Image and Sound
Representation
• Image Representation
• Sound Representation

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2.1.1. NUMBER SYSTEMS
 The study of number
systems is important
from the viewpoint of
understanding how data
are represented before
they can be processed
by any digital system
including a digital
computer.
 It is one of the most
basic topics in digital
electronics.
• Decimal Number System
• Base (RADIX)-r Number System
• Binary System
• Octal System
• Conversion between Number
Systems

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2.1.1.1 DECIMAL NUMBER SYSTEM
 Decimal Number System Using 10
Digits: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9
 The decimal number system with
which we are all so familiar can be
said to have a radix of 10 as it has 10
independent digits, i.e. 0, 1, 2, 3, 4, 5,
6, 7, 8 and 9.
 It is known as the radix or base of
the number system.
 The rule for calculating the value in this number system
is that each digit in any position has a value equal to 10
times the digit in the position immediately to its right.
 The decimal part represents negative powers of 10
from left to right starting from the decimal point.
 The place values of different digits in a mixed decimal number,
starting from the decimal point, are 100
, 101
, 102
and so on (for the
integer part) and 10 1
−
, 10 2
−
, 10 3
−
and so on (for the fractional
part).

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 As an illustration, in the case of the decimal
number 3586.265,
 the integer part (i.e. 3586) can be expressed
as
 3586 = 3×103
+5×102
+8×101
+6×100
 3586 = 3000 +500 +80 +6
 and the fractional part can be expressed as
 0.265 = 2×10-1
+6×10-2
+5×10-3
=
Three five eight six
equals 3 times ten to
the power of 3, + 5
times ten to the
power of 2, + 8 times
ten to the power of 1, +
six times 10 to the
power of 0

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 Number N in the Base-10 Number System. N is represented as follows:
N(10)=anan-1..a1a0 . a-1a-2...a-m
 Where:
 n+1 digits represent the integer part.
 m digits represent the decimal part.
 The value of N in the decimal system is:
N(10)=an*10n
+an-1*10n-1
+…+a1*101
+a0*100
+a-1*10-1
+…+a-m*10-m.
Other Example: 6677.028=6*103
+6*102
+7*101
+7*100
+0*10-1
+2*10-2
+8*10-3

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2.1.1.2 BASE (RADIX)-R NUMBER SYSTEM
 A number system is a set of symbols and rules used to represent and determine the values of
numbers.
 Each number system has a finite number of digits, referred to as its symbols.
 The total number of symbols in a number system is called the base (or radix).
 Example: In the decimal number system,
 It is known as the radix or base of the number system.
 The decimal number system with which we are all so familiar can be said to have a radix of 10
as it has 10 independent digits, i.e. 0, 1, 2, 3, 4, 5, 6, 7, 8 and 9.
 Similarly, the binary number system with only two independent digits, 0 and 1, is a radix-2
number system.
 The octal and hexadecimal number systems have a radix (or base) of 8 and 16 respectively.

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 Base (r - radix):
 Refers to the number of digit characters
(symbols) used to represent values in a
number system.
 Weight:
 A quantity representing the position of a digit
in a number string.
 Weight = BasePosition
 Value:
 Calculated as the weighted sum.
 Value = ∑(Digit × Weight)
 Bases we will use
 Binary: Base 2
 Octal: Base 8
 Decimal: Base 10
 Hexadecimal: Base 16
 Positional number system
 1012= 1×22
+ 0×21
+ 1×20
 638 = 6×81
+ 3×80
 A116= 10×161
+ 1×160

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2.1.1.3 BINARY NUMBER SYSTEM
 With base (r = 2): Using the two digits 0 and 1.
 Each binary digit is called a BIT (Binary digIT).
 Bit is an abbreviation of the term ‘binary digit’ and is
the smallest unit of information. It is either ‘0’ or ‘1’.
 In computers, each component or physical element
that carries information can be found in two opposing
states: on and off, or with current and without
current.
 These two states are utilized to represent the two
digits 0 and 1.
For example: 101.011(2)
 The term octet is used to describe a unit of 8 bits. Most modern computers also have 8 bits in
a byte
 A byte is a string of eight bits.The byte is the basic unit of data operated upon as a single unit in computers.
 A computer word is again a string of bits whose size, called the ‘word length’ or ‘word size’,
 The binary system is particularly well-suited for computer technology.

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Example:
Converting a Number from Binary to Decimal:
 11101.11(2)=1* 24
+1*23
+1*22
+0*21
+1*20
+1* 2-1
+1* 2-2
= 29.75(10)
 110010010.011(2)=?(10)
 110010010.011(2)=?(10) = 1*28
+1*27
+ 0*26
+ 0*25
+ 1*24
+0*23 +
0*22
+ 1*21
+0*20
 (10010110)(2) =?(10)
 (01101010) (2) =?(10)

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2.1.1.4 OCTAL NUMBER SYSTEM
For example:
235.64(8) = ? (10)
235.64(8)
 The octal number system has a radix of 8 and therefore has eight distinct
digits. (Octal number system r=8)
 All higher-order numbers are expressed as a combination of these on the
same pattern as the one followed in the case of the binary and decimal
number systems described in Sections 1.3 and 1.4.
 The independent digits are 0, 1, 2, 3, 4, 5, 6 and 7.The next 10 numbers that
follow ‘7’, for example, would be 10, 11, 12, 13, 14, 15, 16, 17, 20 and 21.
 In fact, if we omit all the numbers containing the digits 8 or 9, or both, from
the decimal number system, we end up with an octal number system.The
place values for the different digits in the octal number system are 80
, 81
, 82
and so on (for the integer part) and 8 1
−
, 8 2
−
, 8 3
−
and so on (for the fractional
part).

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2.1.1.5 HEXADECIMAL NUMBER SYSTEM
 The hexadecimal number system is a radix-16 number system and its 16 basic digits are 0, 1, 2,
3,4, 5, 6, 7, 8, 9,A, B, C, D, E and F.
 Using 10 digits from 0 to 9 and six uppercase letters A, B, C, D, E, F to represent the
corresponding numeric values of 10, 11, 12, 13, 14, 15.
 The place values or weights of different digits in a mixed hexadecimal number are 160
, 161
, 162
and
so on (for the integer part) and 16 1
−
, 16 2
−
, 16 3
−
and so on (for the fractional part).The decimal
equivalent of A, B, C, D, E and F are 10, 11, 12, 13, 14 and 15 respectively, for obvious reasons.
 Some programming languages require the hexadecimal number to have the letter 'H' at the end of
the number
 34F5C(16)= ?(10)
 34F5CH(16)=? (10)

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2.1.1.5 HEXADECIMAL NUMBER SYSTEM

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SUMMARY OF COMMON NUMBER SYSTEMS:

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2.1.1.6 CONVERSION BETWEEN NUMBER SYSTEMS
Method
• (1) Using Table
• (2) Convert throught Decimal Number System
Binary to Decimal
Binary to Octal and
ViceVersa andVice
Versa
• Binary to Octal using Table
Binary to
Hexadecimal and
ViceVersa
• Binary to Hexadecimal using Table
Octal to Hexadecimal
and vice versa
• From Octal to Binary
• Consequence from Binary to Hexadecimal using table
Decimal to any base R
• Decimal to R
• Integer Part of Decimal to Binary
• Fractional Part of Decimal to Binary
• 10 to 2
• 10 to 16

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Using the Conversion
Table between Binary,
Octal, and
Hexadecimal Number
Systems
Convert through the
decimal system.

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 Tables 1 and 2 showing the
conversion between
Decimal, Binary, Octal,
and Hexadecimal systems
for numbers from 1 to 16
Decimal Binary Octal
0 000 0
1 001 1
2 010 2
3 011 3
4 100 4
5 101 5
6 110 6
7 111 7
Decimal Binary Octal Hexadecimal
0 0000 0 0
1 0001 1 1
2 0010 2 2
3 0011 3 3
4 0100 4 4
5 0101 5 5
6 0110 6 6
7 0111 7 7
8 1000 10 8
9 1001 11 9
10 1010 12 A
11 1011 13 B
12 1100 14 C
13 1101 15 D
14 1110 16 E
15 1111 17 F
16 10000 20 10

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BINARY TO HEX/DECIMAL/OCTAL CONVERSION
 Conversion from binary to decimal
 1012= 1×22
+ 0×21
+ 1×20
= 510
 63.48 = 6×81
+ 3×80
+ 4×8–1
= 51.510
 A116= 10×161
+ 1×160
= 16110
 Conversion from binary to octal/hex
 Binary: 10011110001
 Octal: 10 | 011 | 110 | 001=23618
 Hex: 100 | 1111 | 0001=4F116

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BINARYTO OCTAL ANDVICEVERSA
 Binary to Octal:
 Group the binary number into
groups of 3 bits.
 Use the conversion table (Table 1)
to obtain the result.
 For example: 11001011010.1011(2)
= ? (8)
 11001011010.1011(2) = 011 001
011 010.101 100(2) = 3132.54(8)
 Octal to Binary :
 Each digit in the octal system corresponds
to a group of 3 binary bits.
 Use the conversion table (Table 1) to
obtain the result.
 For example: :
 702.16(8) = 111000010.001110(2)

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Convert from Binary to Hexadecimal (usingTable)
Conversion from binary to octal/hex
 Binary: 10011110001
 Hex: 100 | 1111 | 0001=4F116
Convert from Hexadecimal to Binary

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 Convert from Octal to Hexadecimal and vice versa:
 Step 1: Convert from Octal to Binary.
 Step 2: Convert from Binary to Hexadecimal.
 Use the conversion table (Table) to obtain the results.
 Example: 46132
▪ (8) = ? (16)
46132(8) = 100 110 001 011 010 (2)
= 0100 1100 0101 1010(2) = 4 C 5 A(16)
→ 46132(8) = 4C5A(16)

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METHOD FOR CONVERTING A DECIMAL NUMBER TO BASE R
Successive division
 Converting the Integer Part
from Decimal to Base r:
1. Divide the decimal integer N(10)
by r repeatedly until the quotient
is 0.
2. The result of the conversion N(r)
consists of the remainders from
the division, written in reverse
order.
3. For examples 5410 =?2

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FRACTIONAL PART OF DECIMAL TO BINARY
0, 9 3 7 5
X 2
1, 8 7 5 0
X 2
1, 7 5 0 0
X 2
1, 5 0 0 0
X 2
1, 0 0 0 0
 Converting the Fractional
Part from Decimal to Base r:
1. Multiply the decimal fraction N(10)
by r repeatedly until the fractional
part of the product equals 0.
2. The result of the conversion N(r)
consists of the integer parts from
the multiplication, written in the
order of calculation.
3. For examples:
0.9375(10)=?(2)

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For the integer part,
• the binary equivalent can be found by successively
dividing the integer part of the number by 2 and
recording the remainders until the quotient becomes ‘0’.
• The remainders written in reverse order constitute the
binary equivalent.
For the fractional part,
• it is found by successively multiplying the fractional part
of the decimal number by 2 and recording the carry until
the result of multiplication is ‘0’.
• The carry sequence written in forward order
constitutes the binary equivalent of the fractional part of
the decimal number.
• If the result of multiplication does not seem to be
heading towards zero in the case of the fractional part,
the process may be continued only until the requisite
number of equivalent bits has been obtained.
• This method of decimal–binary conversion is popularly
known as the double-dabble method.
• The process can be best illustrated with the help of an
example.
DECIMAL-TO-BINARY CONVERSION

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DECIMAL-TO-BINARY CONVERSION
 An Other Example
 (13.375)10 = ()2

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DECIMAL-TO-OCTAL CONVERSION
The process of decimal-to-
octal conversion is similar to
that of decimal-to-binary
conversion.
• The progressive division in the case of
the integer part and the progressive
multiplication while working on the
fractional part here are by ‘8’ which is
the radix of the octal number system.
• Again, the integer and fractional parts
of the decimal number are treated
separately.The process can be best
illustrated with the help of an
example.

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DECIMAL→ BINARY/OCTAL/HEX CONVERSION
 Why does this work?
 N=5610=1110002
 Q=N/2=56/2=111000/2=11100 remainder 0
 Each successive divide liberates an LSB (least significant bit)

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DECIMAL-TO-HEXADECIMAL CONVERSION
 The process of decimal-to-
hexadecimal conversion is
also similar.
 Since the hexadecimal
number system has a base of
16, the progressive division
and multiplication factor in
this case is 16.
 The process is illustrated
further with the help of an
example.

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EXAMPLE
 Exercise: Perform the following conversions:
a) 12.9375(10)= (2)
b) 498(10)= (8)
c) 1999(10) = (16)
d) 127.6875(10)= (2)
e) 53FC(16)= (10)
f) 0011 0011 0011 0010(2)=(16)
g) BC007(16) = (8)
h) 255.75(10)= (16)

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• Decimal System
• Binary System
• Octal System
Computers
• Overview
Binary Numbers
• 2.1.3.1 Arithmetic Operations with Binary Numbers
• 2.1.3.2 Logical Operations with Binary Numbers
• Signed Integers
Representation
• Overview
2.1.6. Character
Representation
• Overview
• ASCII Code
• Unicode Code
Representation

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2.1.2 DATA ENCODING IN COMPUTERS
2.1.2.1 OVERVIEW
DATA CONVERSION
 Basically, we have two types of data in nature: Analog and Digital.
 Data transmission – Electrical wires (for analog) and databus (for digital).
 Most of the real-world physical quantities are in analog form.
 Data storage and processing – Analog versus Digital. (That’s the idea for data
conversion!!!)

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2.1.2.1 OVERVIEW
ANALOG VS. DIGITAL
Analog signal- one whose output varies continuously in step with the input.
Example:
Analog
Digital signal- one whose output varies at discrete voltage levels commonly called
HIGH or LOW (1 or 0).
Example:
Digital
HIGH or 1
LOW or 0
Time

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2.1.2.1 OVERVIEW
WHY DIGITAL?
 Data can be stored (memory characteristic of digital).
 Data can be used in calculations.
 Compatible with display technologies.
 Compatible with computer technologies.
 Systems can be programmed.
 Digital IC families make design easier.

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2.1.2.1 OVERVIEW
WHY ANALOG?
 Most “real-world” events are analog in nature.
 Analog processing is usually simpler.
 Analog processing is usually faster.
 Traditional electronic systems were mostly analog in nature.
 Digital data processors – Microprocessors, DSPs, FPGAs etc.
 So, when a data conversion needed? –When digital devices interface with
analogue devices and vice versa.

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2.1.2.1 OVERVIEW
DATA CONVERSION - FBW FLIGHT CONTROL SYSTEM
 Basic components of a FBW flight control system
 Can we locate a
place in an airplane
where digital
systems interface
with analogue
systems?
 A most critical
system – Flight
Control System
(FCS).

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2.1.2.1 OVERVIEW
FLIGHT CONTROL COMPUTER (FCC)
 FCC used in LCA Flight Control Computer
 (Courtesy: DRDO, India) (Courtesy: Curtiss-Wright
Controls Defense Solutions, US)

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2.1.2.1 OVERVIEW
DATA CONVERSION CIRCUITS
 Digital-to-Analog (D/A) and Analog-to-Digital (A/D) converters (DAC and ADC).
 Application of A/D and D/A converters
 Today, both ADC and DAC are available in IC form.

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2.1.2.1 OVERVIEW
ADC AND DAC
 Applications – digital audio recording and playback, computers, data acquisition, digital
multimeter, digital control, digital signal processing, microprocessor based
instrumentation.
 Since most of the ADCs use DACs in their inside, we have to discuss DAC first.

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2.1.2.1 OVERVIEW
GENERATING A DIGITAL SIGNAL (WITH SWITCH)
Note: signal goes H, L, H,
UNDEFINED, and finally HIGH.
CAUTION:
Switch bounce
may cause problems.
Debounced Switch
HIGH
LOW
Debouncing
Latch
time
0V time
HIGH
undefined
LOW
+5V

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2.1.2.2 INFORMATION UNITS
The smallest unit representing information is the Bit (Binary digIT).
A Bit corresponds to an event with one of two states: off or on.
Binary arithmetic uses the two numbers 0 and 1 to represent values.
Since the usability of the two numbers 1 and 0 is equal, an instruction
consisting of a single binary digit can be considered the smallest unit of
information.
In computer science, larger units of information measurement are used as
follows: Byte (B), KiloByte (KB), MegaByte (MB), GigaByte (GB),TeraByte
(TB).

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Name Symbol Value
Byte B 8 bit
KiloByte KB =210
B = 1024 B
MegaByte MB =210
KB = 220
B
GigaByte GB =210
MB = 230
B
TeraByte TB =210
GB = 240
B
Petabytes PB =210
TB = 250
B
Exabytes EB =210
PB = 260
B
Zettabytes ZB =210
EB = 270
B
Yottabytes YB =210
ZB = 280
B
Brontobytes BB =210
YB = 290
B
GepBytes GeB =210
BB = 2100
B
CONVERSION BETWEEN INFORMATION MEASUREMENT UNITS

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• Decimal System
• Binary System
• Octal System
Computers
• Overview
Binary Numbers
• Arithmetic Operations with Binary Numbers
• Logical Operations with Binary Numbers
• Signed Integers
Representation
• Overview
2.1.6. Character
Representation
• Overview
• ASCII Code
• Unicode Code
Representation

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2.1.3.1 OPERATIONSWITH BINARY NUMBERS
 A logical proposition is a
statement that can take one of
two values:
 True (TRUE)
 or False (FALSE).
 This is equivalent to
 TRUE = 1
 and FALSE = 0.
 Rules:
 TRUE = NOT FALSE
 FALSE = NOT TRUE

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Addition
Subtraction

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Multiplication
Division

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Division

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Let's perform the binary division of 100100012 (which is
145 in decimal) by 1011210112(which is 11 in decimal)
 Step 1 Compare the first group of bits
 Take the first 4 bits of the dividend, which is 10012(this
is 9 in decimal).
 10012=9 is smaller than 10112=11, so bring down the
next bit to get 100102 (this is 18 in decimal).
 Step 2: Divide 100102 by 10112
 Now, compare 100102=18 with 10112=11.
 100102is greater than 10112
, so subtract:
100102−10112=01112(this is 7 in decimal)
 Write 1 in the quotient.
 Step 3: Bring down the next bit
 Bring down the next bit (0) from the dividend, so now
we have 011102(which is 14 in decimal).
• Compare 011102=14 with 10112=11.
 Step 4: Divide 011102 by 10112
 Subtract: 011102−10112=00112(this is 3 in decimal)
 Step 5: Bring down the next bit
 Bring down the next bit (0), making it 001102
(which is 6 in decimal).
 001102=6 is smaller than 10112=11, so we cannot
divide.
 …

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2.1.3.1 OPERATIONS WITH BINARY NUMBERS
2.1.3.2 LOGICAL OPERATIONS WITH BINARY NUMBERS
Negation (Not):
The complement operator is a unary
operator that negates the value of each
bit of its operand.
This means it will change 0 to 1 and 1
to 0.
TruthTable:
X Not X
0 1
1 0

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2.1.3.1 OPERATIONS WITH BINARY NUMBERS
 Bitwise AND Operator:
The AND operator is a binary
operator that operates on each bit of
two bits strings of equal length,
producing a new bit string of the same
length.
TruthTable for AND:
X Y X ANDY
0 0 0
0 1 0
1 0 0
1 1 1

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 Bitwise OR Operator:
The OR operator is a binary
operator that operates on each bit
of two bits strings of equal length,
producing a new bit string of the
same length.
TruthTable for OR:
X Y X ORY
0 0 0
0 1 1
1 0 1
1 1 1

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 Bitwise XOR (Exclusive OR) Operator:
The XOR operator is a binary operator that
operates on each bit of two bits strings of equal
length, producing a new bit string of the same
length, with the condition that the result is true
(1) if the bits are different and false (0) if they
are the same.
TruthTable for XOR:
X Y X XOR
Y
0 0 0
0 1 1
1 0 1
1 1 0

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EXAMPLE
Let’s perform the specified logical operations with the given values X=117,Y=93, and
Z=35 in 8-bit binary.
1. Not X
2. X ORY
3. Y And Z
4. Y XOR Z

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EXAMPLE
Let’s perform the specified logical operations with the given values X=117,Y=93, and
Z=35 in 8-bit binary.
Step 1: Convert Decimal to 8-bit
Binary
1.X = 117:
1. Decimal: 117
2. Binary: 01110101
2.Y = 93:
1. Decimal: 93
2. Binary: 01011101
3.Z = 35:
1. Decimal: 35
2. Binary: 00100011

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Let’s perform the specified logical operations with the given values X=117X =
117X=117,Y=93Y = 93Y=93, and Z=35Z = 35Z=35 in 8-bit binary.
EXAMPLE

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2.1.4 REPRESENTATION OF INTEGERS
2.1.4.1 UNSIGNED INTEGERS
 All bits are used to represent the numeric value.
 Examples:
 With 8 bits, it can represent 28
=256 non-negative integers with a value range from 0 to 255.
 With 16 bits, it can represent 216
=65,5362 integers with a value range from 0 to
65,535.
 With n bit? an-1an-2 ….a2a1a0

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 Represent the following unsigned integers using
8 bits:
 A = 45 B = 156
A = 45 = 32 + 8 + 4 + 1 = 25
+ 23
+ 22
+ 20
→ A = 0010 1101(2)
B = 156 = 128 + 16 + 8 + 4 = 27
+ 24
+ 23
+ 22
→ B = 1001 1100(2)
• For n = 8 bits:
• The range of representation is
[0,255]
0000 0000 = 0
0000 0001 = 1
0000 0010 = 2
0000 0011 = 3
.....
1111 1111 = 255

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 For n=8 bits:
 Note the case of calculations exceeding the representation range.
 Example:
 123 + 164 =?
 OR
1111 1111
+ 0000 0001
1 0000 0000
 OR Wrong Result: 255 + 1 = 0 ? (due to overflow in addition)

64
2.1.4.2 SIGNED INTEGERS
 How do we write negative binary numbers?
 Historically: 3 approaches
 Sign-and-magnitude
 Ones-complement
 Twos-complement
 For all 3, the most-significant bit (MSB) is the sign
digit
 0 positive
≡
 1 negative
≡
 twos-complement is the important one
 Simplifies arithmetic
 Used almost universally
 0110 = 610
 1001 = 910
 1010 = 1010

65
Example:
 Consider n=4 bits, A=0110
 One's complement of A: (24
−1) −0110
=1001
 Two's complement of A: 24
−0110 =1010
 You can find the one's complement of A by
inverting all the bits.
 Two's complement = One's complement + 1.
 A+Two’s complement of A=0, if you ignore the
carry bit from the most significant bit.

66
 Determine the value of the signed
8-bit integer as follows:
▪ A = 0101 0110
 B = 1101 0010
 B = -27
+ 26
+ 24
+ 21
= -128 + 64 + 16 + 2
= -46

67
[-2n-1
, 2n-1
-1]
an-1an-2 ….a2a1a0

68
Method 2:
 B = 1101 0010
 B = -27
+ 26
+ 24
+ 21
= -128 + 64 + 16 + 2 = -46
Determine the value of the signed 8-bit integer as
follows: B = 1101 0010 = (21010)
Step 1: Check the sign
• In an 8-bit signed integer using two's complement, the most
significant bit (MSB) indicates the sign:
• If the MSB is 0, the number is positive.
• If the MSB is 1, the number is negative.
• Here, the MSB is 1, indicating that the number is negative.
Step 2: Find the two's complement
• To find the value of a negative number in two's complement:
• 1) Invert all the bits (one's complement).
• 2) Add 1 to the inverted result.
• Binary number: 1101 0010
• One's complement (invert the bits): 0010 1101
• Add 1:
0010 1101 + 1= 0010 1110
Step 3: Convert the result to decimal
• Now, convert 0010 11102 to decimal:
• 0×27
=0
• 0×26
=0
• 1×25
=32
• 0×24
=0
• 1×23
=8
• 1×22
=4
• 1×21
=2
• 0×20
=0
• So, 32+8+4+2=46
Step 4:Apply the negative sign
• Since the original number was negative, the final
value is -46

69
Signed Integer (Example with n=8 bits)
In 2’s complement representation MSB is sign bit, (n-1) bits of the
represent magnitude of the number.
Conversion sample for 8-bit word is shown in figure.

70
2.1.4 REPRESENTATION OF INTEGERS  2.1.4.2 SIGNED INTEGERS
SIGN-AND-MAGNITUDE
 The most-significant bit (MSB) is the sign
digit
 0 ≡ positive
 1 ≡ negative
 The remaining bits are the number’s
magnitude
 Problem 1:Two representations
for zero
 0 = 0000 and also –0 = 1000
 Problem 2:Arithmetic is
cumbersome

71
ONES-COMPLEMENT
 Negative number: Bitwise complement positive number
 0011 ≡ 310
 1100 ≡ –310
 Solves the arithmetic problem
 Remaining problem:Two representations for zero
 0 = 0000 and also –0 = 1111

72
TWOS-COMPLEMENT
 Negative number: Bitwise complement plus one
 0011 ≡ 310
 1101 ≡ –310
 Number wheel
0000
0001
0011
1111
1110
1100
1011
1010
1000 0111
0110
0100
0010
0101
1001
1101
0
+ 1
+ 2
+ 3
+ 4
+ 5
+ 6
+ 7
– 8
– 7
– 6
– 5
– 4
– 3
– 2
– 1
 Only one zero!
 MSB is the sign
digit
 0 ≡ positive
 1 ≡ negative

73
TWOS-COMPLEMENT (CON’T)
 Complementing a complement the original number
 Arithmetic is easy
 Subtraction = negation and addition
 Easy to implement in hardware

74
2.1.4.3 PERFORMING ARITHMETIC OPERATIONSWITH INTEGERS
ADDITION AND SUBTRACTION WITH INTEGERS
 Unsigned Integer Addition/Subtraction
 Perform addition or subtraction bit by bit from right to left.
 When adding or subtracting unsigned n-bit integers, the result will also be
an unsigned n-bit integer.
 If the sum of the two numbers is less than or equal to 2𝑛
1, the result will be
−
correct.
 If the sum of the two numbers exceeds 2𝑛
1, there will be an
− overflow, and the
result will be incorrect.
 In subtraction with unsigned numbers, subtract the larger number from the smaller
one; otherwise, the result will be incorrect.

75
2.1.4.3 PERFORMING ARITHMETIC OPERATIONS WITH INTEGERS
UNSIGNED INTEGER ADDITION/SUBTRACTION

76
SIGNED INTEGER ADDITION/SUBTRACTION
• Add corresponding bits from left to right, ignoring any carry if it occurs.
• Adding two numbers with different signs always gives a correct result.
• Adding two numbers with the same sign:
• The result is correct if it falls outside the range of 2
− n 1
−
to 2n 1
−
1.
−
• The result is correct if the sum has the same sign as both operands,
and incorrect if the sum has a different sign from the operands (this is
called overflow).
 Example: (+15)+( 13)
−

80
 Signed Integer Subtraction
• To subtract two signed integers X andY,
take the two's complement ofY, which is
Y, then add X to Y. In other words:
− −
X Y=X+( Y).
− −
• Add the corresponding bits from right to
left, ignoring any carry (if present).
• Example:
Given A= 25
− 10and B=+5810 as two
integers encoded in 8-bit format, which
of the following statements is correct?
a. A = 1010 0111
b. B = 0011 0110
c. A + B = 0010 0001
d. A – B = 1010 1101

81
Given A= 25
− 10and B=+5810 as two integers encoded in 8-bit format, which of the
following statements is correct?
a. A = 1010 0111  S A= 11100111(2)
b. B = 0011 0110  S B= 00111010(2)
c. A + B = 0010 0001 Correct A+B=1 00100001
d. A – B = 1010 1101 Correct
A 11100111(2)
B 00111010(2)
A- B 10101101

82
2.1.6. CHARACTER REPRESENTATION
 In computers, characters also need to be converted into binary bit strings, called the
code of those characters.The number of bits allocated for each character varies
between different coding schemes.Two common coding schemes are:
• ASCII (American Standard Code for Information Interchange), which uses 8
bits to encode a character.
• Unicode, which uses 16 bits.
 Additionally, there are other coding schemes, such as:
• BCD (Binary Coded Decimal), which uses 6 bits.
• EBCDIC (Extended Binary Coded Decimal Interchange Code), which uses 8
bits.

83
AMERICAN STANDARD CODE FOR
INFORMATION INTERCHANGE
Hexa-decimal 0 1 2 3 4 5 6 7
0 <NUL>
0
<DEL>
16
<SP>
32
0
48
@
63
P
80
`
96
p
112
1 <SOH>
1
<DC1>
17
!
33
1
49
A
65
Q
81
a
97
q
113
2 <STX>
2
<DC2>
18 34
2
50
B
66
R
82
b
98
r
114
3 <ETX>
3
<DC3>
19
#
35
3
51
C
67
S
83
c
99
s
115
4 <EOT>
4
<DC4>
20
$
36
4
52
D
68
T
84
d
100
t
116
5 <ENQ>
5
<NAK>
21
%
37
5
53
E
69
U
85
e
101
u
117
6 <ACK>
6
<SYN>
22
&
38
6
54
F
70
V
86
f
102
v
118
7 <BEL>
7
<EBT>
23
‘
39
7
55
G
71
W
87
g
103
w
119
8 <BS>
8
<CAN>
24
(
40
8
56
H
72
X
88
h
104
x
120
9 <HT>
9
<EM>
25
)
41
9
57
I
73
Y
89
i
105
y
121
A <NL>
10
<SUB>
26
*
42
:
58
J
74
Z
90
j
106
z
122
B <VT>
11
<ESC>
27
+
43
;
59
K
75
[
91
k
107
{
123
C <FF>
12
<FS>
28
,
44
<
60
L
76

92
l
108
|
124
D <CR>
13
<GS>
29
-
45
=
61
M
77
]
93
m
109
}
125
E <SO>
14
<RS>
30
.
46
>
62
N
78
^
94
n
110
~
126
F <SI>
15
<US>
31
/
47
?
63
O
79
-
95
o
111
<DEL>
127

84
2.1.6.2 ASCII
 The Standard Information Exchange
Code of the United States
 Control Characters: The first 32
characters of the ASCII coding table are
used to encode control information,
which is used for transmitting
information to screens, printers, and
other computers.
 For example, these control characters
are utilized for formatting control.
 The codes from 32 to 126 are used to encode
common display characters, which are divided
into three groups as follows:
1. Latin Letters:
1. Lowercase letters: 26 letters from a to z, with
codes ranging from 97 to 122.
2. Uppercase letters: 26 letters from A to Z, with
codes ranging from 65 to 90.
2. Decimal Digits:
1. 10 digits from 0 to 9, assigned codes from 48 to 57.
3. Other Characters:
1. Punctuation marks, mathematical operators, and
whitespace characters.

85
2.1.6.2 ASCII
 Extended Characters:
• The codes ranging from 128 to 255 depend on the manufacturers of computers and
software developers.
• For example:
• The extended code of IBM is used for IBM series computers.
• The extended code of Apple is used for Macintosh computers.
• The TCVN 5712 code includes specific characters for the Vietnamese language.

86
2.1.6.3 UNICODE
 Universal Character
Set for Different
Languages
 Unicode is a 16-bit
character encoding
standard that is fully
compatible with the
international standard
ISO/IEC 10646-1:1993.
The number of characters
that can be represented is
216
(65,536).
 Some Characteristics of Unicode:
 Each character in the Unicode coding table has a length of 16 bits,
making it straightforward to process Unicode character strings.
 Unicode minimizes the definition of redundancy and duplication.
For example, the character “ê” has a unique code that is shared
across bothVietnamese and other languages, resulting in
Vietnamese characters being scattered across various non-
contiguous locations. Unicode still reserves specific areas to define
characters for particular languages. For many languages, specific
algorithms are needed for sorting.
 To use Unicode, software that supports displaying or inputting
characters according to the Unicode standard is required, along
with the installation of Unicode fonts in the system.

87
2.1.6.3 UNICODE
 Vietnamese Language in the Unicode Encoding
• Vietnamese: Extended Latin 1 allows for readingVietnamese anywhere that Unicode
is installed.
• Vietnamese characters in Unicode can have two forms:
• Precomposed Characters
• Combining Characters
• Unicode includes a total of 134 characters for all uppercase and lowercase letters in
theVietnamese alphabet, with codes for 5 tonal marks (huy n, s c, h i, ngã, n ng) to
ề ắ ỏ ặ
create combinedVietnamese characters.
• Unicode has a specific character to represent the currency unit Vietnamese đ ng
ồ .

88
2.1.7. IMAGE AND AUDIO REPRESENTATION
 Image Representation
• Static Image Representation
• Dynamic Image Representation

89
 Static Image Representation
 Static images include icons, logos, and photographs.
Images are represented according to two graphic principles: pixel graphics and vector
graphics.
• Pixel Graphics: Images are represented using a pixel matrix.
• For black-and-white images (two colors), each bit corresponds to one color (bit 1 represents black, bit 0
represents white).
• For high-quality color images, more information is needed to represent the color of each pixel.
• Color Images:
• 256 colors: requires 8 bits (pseudo-color).
• 65,536 colors: requires 16 bits (high color).
• With 24 bits, it can represent all colors distinguishable by the human eye (true color).

90
 Static Image Representation
• Pixel Graphics
• Vector Graphics:
• Divides an image into fundamental objects such as points, lines, polygons, surfaces, and
volumes.
• The computer uses vector mathematical formulas to reconstruct the image from these basic
objects.
• Object-oriented graphics: Each object and its properties can be encoded using a concise
command in vector graphics, while also allowing for the representation of three-dimensional
objects.

91
 Dynamic Image Representation
• Motion images include an additional parameter for representation: time.
• The representation of moving images is similar to the principle used in film:
• 30 frames per second is the rate at which humans perceive a smooth motion (images are
retained on the retina).
• To display one second of moving images, a computer needs sufficient memory capacity to store 30
static images, and the computer's processor must be fast enough to handle the data volume of 30
static images within one second.

92
 Dynamic Image Representation
 Due to the high volume of information and quality of dynamic images, conventional
techniques cannot meet the demands for high-resolution digital video with true color.
 DigitalVideo Compression:This involves compressing each static frame and
compressing portions of the image that do not change over time.
 For example:When transmitting video from a meeting, the entire office scene is
transmitted initially, and subsequently, only the changes occurring within that office
space are sent.

93
 Audio Representation
 Audio encoding involves
converting sound into binary
format by sampling it into multiple
values at regular time intervals.
Each of these values is assigned a
binary code and stored in a file.
 For example:
• Encoding audio with 8 bits will
yield 256 different values.
• Encoding audio with 16 bits will
provide 65,536 different values.

94
CHAPTER II. INFORMATION REPRESENTAITON AND COMPUTER
ORGANIZATION
• 2.1.1 Number Systems
• 2.1.2 Data Encoding in Computers
• 2.1.3 Logical Operations with Binary Numbers
• 2.1.4 Integer Representation
• 2.1.5 Floating-Point Number Representation
• 2.1.6 Character Representation
• 2.1.7 Audio and Image Representation
2.1. Data Representation on Electronic Computers
• 2.2.1 Basic Computer Model
• 2.2.2 Central Processing Unit (CPU)
• 2.2.3 Memory
• 2.2.4 Input-Output Systems
• 2.2.5 System Interconnection (Buses)
• 2.2.6 Peripheral Devices
2.2 Organization of Computer Systems

95
2.2 ORGANIZATION OF COMPUTER SYSTEMS
2.2.1 BASIC COMPUTER MODEL
• The computer is made up of
several different components.
• This is what makes up a
computer

96
System Board (Motherboard)
 The system board is a printed circuit board that contains most of the computer's
circuits and provides pathways for communication between all components and devices
connected to the computer.
 Internal components of the computer are mounted on the system board.
 The system board also provides ports for connecting external devices such as a mouse,
speakers, chargers, etc.

97
Data Processing:This is the most important function of a computer, as data comes in
various forms and requires different processing methods.
Data Storage: Input data or processing results can be stored for later retrieval.
Data Exchange andTransmission: Facilitates the transfer of data between different
components or systems.
Control: Manages the various functions and operations of the computer system.

98
 Main Functions of the Components:
Central Processing
Unit (CPU):
• Controls the
computer's
operations and
performs data
processing.
Main Memory:
• Stores programs
and data for
quick access by
the CPU.
Input/Output
System:
• Facilitates the
exchange of
information
between the
external
environment and
the computer.
System Bus:
• Connects and
transports
information
between the
CPU, main
memory, and
input/output
systems of the
computer.

 Basic Operation of a
Computer:
 The fundamental operation of
a computer involves executing
programs.
 This execution consists of
repeatedly cycling through an
instruction cycle, which
includes the following steps:
99
2.2.1 BASIC MODEL OF A COMPUTER
Fetch:
1.The CPU fetches the address from the instruction pointer to the memory location
containing the instruction to be received.
Load:
•The CPU retrieves the instruction from memory and loads it into the instruction register.
Increment:
•The instruction pointer is incremented to point to the next storage location.
Decode:
•The CPU decodes the instruction to determine the operation to be performed.
Addressing:
•If the instruction requires data from memory or I/O ports, the CPU identifies the address
where the data is stored.
Load Data:
•The CPU loads the necessary data into its registers.
Execute:
•The CPU executes the instruction
•Store Result:The result is written to the specified location.

10
2.2.2 CENTRAL PROCESSING UNIT - CPU
•The Central
Processing Unit is
the brains of the
computer.
•This hardware
makes the computer
work by telling all
the components
what to do and
when to do it

Math calculations
Access, decode,
coordinate instructions
Hold program
instructions and data

10
 Tasks of the CPU:The CPU is responsible for controlling the components of the computer and
processing data. It operates according to the programs stored in main memory, decoding
instructions to generate control signals that execute commands.
 During instruction execution, the CPU communicates with both main memory and I/O systems.The
CPU consists of three main components:
1. Control Unit:This part of the CPU directs the operation of the processor and its interactions
with other components. It manages the execution of instructions by controlling the timing and
sequence of operations.
2. Arithmetic and Logic Unit (ALU):This component performs all arithmetic calculations
(addition, subtraction, multiplication, division) and logical operations (such as comparisons).
3. Register Set:A collection of small, high-speed storage locations within the CPU used to
temporarily hold data and instructions during processing. Registers facilitate quick access to
frequently used values and intermediate results.

10
 Control Unit (CU):
• The Control Unit receives program instructions from memory and brings them into
the CPU.
• Its primary function is to decode these instructions and generate control signals that
direct the operation of other components of the computer, either according to user
commands or based on pre-installed programs.

10
 Arithmetic Logic Unit (ALU):
• The ALU consists of components that perform:
• Arithmetic operations (addition, subtraction, multiplication, division, etc.)
• Logical operations (AND, OR, NOT, XOR)
• Relational operations (comparisons like greater than, less than, equal to)
• Data from memory or input/output devices is transferred into the CPU's registers,
then sent to the ALU. Here, the data is processed, after which the results are returned
to the registers and can be stored back in memory or sent to output devices.

10
 Arithmetic Logic Unit (ALU):
• The word length of the operands processed directly in the ALU is commonly 32 bits or 64 bits in
modern computers.
• Initially, the ALU consisted only of the Integer Unit (IU) for performing integer calculations.To enhance
its capabilities for floating-point arithmetic, the ALU has been augmented with a Floating Point Unit
(FPU), also known as a Co-Processing Unit.

10
 Register File
 The register file is tightly integrated with
the CPU using electronic circuits that
serve as intermediate memory for the
CPU.
 Registers perform specialized functions
that help increase the speed of information
exchange within the computer.
 Modern CPUs typically have anywhere
from a few dozen to several hundred
registers.
The length of registers can vary, ranging
from 8 bits to 64 bits.
In addition, the CPU is equipped with a
clock, also known as a clock generator or
pulse generator.
The higher the frequency of the clock, the
faster the information processing speed.
The clock frequency is usually aligned with
the machine's configuration, with typical
frequencies including 2.0 GHz, 2.2 GHz,
2.5 GHz, 2.6 GHz, and so on.

10
 Functions of the CPU
• Control the Operations of the
Entire Computer System:The
CPU oversees the functioning of all
components and processes within
the computer.
• Data Processing: It handles all data
processing tasks, ensuring
computations and operations are
performed accurately and efficiently.
Principles of Operation
The CPU operates based on the program stored in the
main memory by following these steps:
1.Fetch Instructions: It retrieves instructions from the
main memory.
2.Decode Instructions:The CPU decodes the fetched
instructions and generates control signals to execute
them.
3.Data Exchange:The CPU can exchange data with
the main memory or I/O systems as needed.
4.Execute Instructions: It performs the operations
defined by the instructions.
5.Store Results:The CPU writes the results back to
the appropriate memory location or output device.

10
 Two Main CPU Lines
• Intel: Notable models include Pentium, Core 2
Duo, Core i3, i5, i7, etc.
• AMD: Key models include Opteron,Athlon, etc.
 Microprocessor
 A microprocessor is a CPU manufactured on a
single microchip.While the term "CPU" can refer
to the processing unit of a computer, modern
microprocessors have a much more complex
architecture compared to basic CPUs.

10
 Processor Speed
• The processing speed of a computer depends on the speed of the processor.
• Processor Speed Metrics:
• MIPS (Millions of Instructions Per Second):This metric indicates the number of
instructions executed in one second.
• Challenges in Evaluation:Accurately assessing processor speed is difficult because it also
depends on other factors, such as internal memory and graphics card performance.
• Indirect Assessment: Processor speed is often evaluated indirectly through the clock
frequency of the microprocessor. For example, a processor with a speed of 2 GHz has a clock
frequency of 2 GHz.

11
 Processor Speed in
Supercomputers
• Roadrunner (3rd Place):
• Manufacturer: IBM
• Cost: 133 million USD
• Speed: 1.04 petaflops (1.04 million trillion
calculations per second)
• Comparison:This speed is equivalent to
the total calculations performed by 6 billion
users using handheld calculators for 24
hours a day, 7 days a week, over 46 years, in
just 1 day.
•Nabulae (2nd Place):
• Location: China
• Speed: 1.2 petaflops
•Jaguar (1st Place):
• Location: USA
• Speed: 1.8 petaflops

11
2.2.3 MEMORY
 Memory in Computers
• Purpose: Memory is a device for storing information during the processing of data by a
computer.
• Types of Memory:
• Internal Memory:Also known as primary memory or RAM (Random Access Memory), this is where data
and programs currently in use are stored for quick access by the CPU.
• External Memory:Also known as secondary memory or storage, this includes devices like hard drives,
SSDs (Solid State Drives), USB drives, and optical discs. It is used for long-term storage of data and
programs.
• Basic Operations:The fundamental operations of memory include:
• Read: Retrieving data from memory.
• Write: Storing data into memory.

11
2.2.3 MEMORY
Random-access memory is a form of
temporary computer data storage.
This is where all your files and programs
are stored on your computer when it is
switched on.
RAM is volatile memory that temporarily
stores the files you are working on.
ROM is non-volatile memory that
permanently stores instructions for your
computer.

11
2.2.3 MEMORY
 Internal Memory
• Definition: Internal memory refers to the
memory components that the CPU can
directly interact with. It is essential for the
execution of instructions and the utilization
of data.
• Characteristics:
• Direct Interaction:The CPU can directly
access both the instructions it executes and
the data it uses from the internal memory.
• Capacity:Although internal memory may
not have a large capacity, it compensates for
this with high-speed data transfer capabilities.
•Types of Internal Memory:
• Main Memory
• This is where the primary programs and data are
stored. It typically includes RAM and ROM.
• Cache Memory (B nh cache)
ộ ớ :
• A small-sized type of volatile memory that
provides high-speed access to frequently used
data and instructions, reducing the time it takes
for the CPU to access data from the main
memory.
• Cache memory is much faster than main
memory but has a smaller capacity. It helps
improve overall system performance by storing
copies of frequently accessed data and
instructions.

11
 Main Memory (Primary Memory)
• Definition: Main memory is a fundamental component present in all computer systems.
• Function:
• Stores programs and data that are actively being used by the CPU.
• Organization:
• Organized into memory cells, each of which has a unique address.
• Typically structured in bytes, where each byte consists of 8 bits.
• The contents of memory cells can change (read/write operations), but the physical addresses of these memory
cells remain fixed.
• Components: Main memory generally consists of two parts:
• ROM (Read-Only Memory): Non-volatile memory that stores firmware and system-level programs. Data in
ROM is not lost when the power is turned off.
• RAM (Random Access Memory):Volatile memory used for temporary storage of data and programs that
are currently in use. Data in RAM is lost when the power is turned off.
2.2.3 MEMORY

11
2.2.3 MEMORY
 ROM (Read-Only Memory)
• Definition: ROM is a type of non-volatile memory that is used primarily to store
firmware or software that is closely tied to specific hardware.
• Read-Only: Information stored in ROM cannot be modified or written to during normal
operation. It is primarily designed for reading.
• Non-Volatile: Data remains intact even when the power is turned off, making it suitable for
storing essential system information.
• Uses:
• System Programs: Stores critical system programs and firmware that are necessary for
booting and operating the computer.
• Input/Output Control: Contains programs that control the input/output devices, ensuring
proper communication between the hardware and the operating system.
• Integration:
• Typically integrated into hardware devices, such as motherboards and embedded systems, at
the time of manufacture.
• Alternate Name: Sometimes referred to as ROM BIOS (Basic Input/Output
System), which contains the essential instructions for booting the computer and
performing hardware initialization.

11
2.2.3 MEMORY
 RAM (Random Access Memory)
• Definition: RAM is a type of volatile memory used for temporarily storing data
and programs that the CPU needs during operation and computation.
• Volatile Memory:The information stored in RAM is lost when the power is
turned off or the machine is shut down.
• Random Access: Data can be read from and written to RAM in any order, making
it fast and efficient for processing tasks.
• Uses:
• Temporary Storage: Used to hold data and programs that are currently in use by
the CPU, allowing for quick access and manipulation.
• Multitasking: Enables multiple applications to run simultaneously by providing
space for their active data.
• Common Capacities:Typical RAM sizes for personal computers range from
2GB to 4GB, but higher capacities (e.g., 8GB, 16GB, or more) are often used in
modern systems for better performance.

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 SRAM (Static RAM)
 Definition: SRAM is a type of volatile memory that retains data as long as power is supplied. It is different from
DRAM (Dynamic RAM) in its structure and functionality.
 Characteristics:
 Complex Structure: SRAM has a more intricate design, using multiple transistors for each memory cell,
leading to its complexity.
 Small Capacity: Due to its complex structure, SRAM typically has a smaller storage capacity compared to
DRAM.
 Fast Speed: Offers faster access times than DRAM, making it ideal for applications requiring high-speed
memory.
 High Cost:The complexity of its design results in a higher manufacturing cost, making it more expensive than
DRAM.
 Uses:
 Cache Memory: Commonly used as cache memory in CPUs and other devices due to its speed, allowing for
quick access to frequently used data.
 Performance Enhancement: Helps improve overall system performance by reducing the time the CPU spends
waiting for data.
2.2.3 MEMORY

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 DRAM (Dynamic RAM)
 Definition: DRAM is a type of volatile memory that stores each bit of data in a separate capacitor within an
integrated circuit. It is widely used as the main memory in computers and other devices.
 Characteristics:
 Simple Structure: DRAM has a simpler design compared to SRAM, using only one transistor and one capacitor
per memory cell, making it less complex.
 Large Capacity: Due to its simpler structure, DRAM can be produced in higher densities, allowing for larger
storage capacities.
 Slower Speed: DRAM requires periodic refreshing to retain data, which makes it slower than SRAM.
 Lower Cost: DRAM is cheaper to manufacture due to its simpler design and higher density, making it a cost-
effective option for large memory needs.
 Uses:
 Main Memory: DRAM is commonly used as the main system memory (RAM) in computers, smartphones, and
other devices where large amounts of storage are required for active data and applications.
 General Computing: It serves as the primary memory in most devices, where its large capacity is more
important than the speed offered by SRAM.
2.2.3 MEMORY

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 Speed and Capacity:
• Faster than RAM: Data in Cache is accessed much faster
than in RAM, helping reduce latency when the CPU
performs tasks that require data.
• Smaller capacity: Despite its high speed, Cache typically
has a much smaller capacity than RAM, just enough to
temporarily store important or frequently used data.
 Hierarchical Structure:
• Cache L1, L2, L3: Cache is typically divided into levels,
with L1 being the smallest and fastest, located closest to
the CPU. L2 and L3 have larger capacities but are slightly
slower than L1.
 Existence:
• Cache may or may not be present: Some systems have
integrated Cache, while others do not. However, modern
CPUs almost always have Cache to optimize processing
speed.
2.2.3 MEMORY
 Cache Memory
Reason for use:
Speed discrepancy: The CPU operates at very
high speeds, often far exceeding the speed of
data access from RAM. If the CPU has to wait
for data from RAM, it won't fully utilize its
processing power. Cache memory is designed to
minimize this wait time.
 Function:
Temporary data storage: Cache is a fast
memory buffer that stores blocks of data from
RAM that the CPU is likely to use repeatedly.
This allows the CPU to handle data more quickly
from the Cache instead of waiting for it from
RAM.
 Integration:
In the processor chip: Cache memory is now
often integrated directly into the processor chip
to ensure the fastest possible data retrieval.

2.2.3 MEMORY
 ROM-BIOS chips are responsible for booting the computer, checking the system
memory, and loading the operating system.
 When the BIOS commands are loaded:
• The computer searches for a valid operating system (the boot sequence determines
the order of the drives accessed when the machine looks for the operating system
files: C drive, optical drive, USB drive).
• The operating system is loaded into RAM and occupies a certain amount of RAM
during system operation.
• The operating system takes control and displays the type of operating system on the
screen.

2.2.3 MEMORY
 To perform tasks, the computer will use a necessary amount of RAM to complete
each task:
• Starting an application:The computer loads a copy of the application’s commands
into RAM (it remains in RAM until you close it).
• Working within the application:The work is stored in RAM until you save it.
• Closing an application:This completes the task and frees up RAM for other
applications.
• Closing programs and shutting down the computer.

2.2.3 MEMORY
 There are many types of external memory:
• Magnetic memory: Hard disk, floppy disk
• Optical memory: CD, DVD (DigitalVideo Disc or DigitalVersatile Disc), etc.
• Semiconductor memory: Flash disk, memory card

2.2.3 MEMORY
 Hard Disks:
• They are central storage devices inside the computer,
used to store data and programs.
• Software programs (including the Operating System)
must be installed on the hard disk before use.
• Traditional hard drives (HDD):
• HDD: Hard Disk Drives
• Solid-state drives (SSD):
• SSD: Solid State Drives

2.2.3 MEMORY
 Flash sticks or memory - USB:
• Connects to the computer via a USB port
• Size:Various capacities such as 8GB, 16GB, etc.
• Widely used for:
• Storing personal data
• Use in audiovisual devices

2.2.3 MEMORY
 SD Card (Secure Digital Cards):
 A small, high-capacity flash memory storage device.
 Commonly used in digital cameras, camcorders, mobile phones, tablets, MP3 players,
and GPS systems.

2.2.3 MEMORY
 Optical Discs and Drives:
• Designed to read CDs (Compact Discs) and DVDs (DigitalVersatile/Video Discs).
• A CD-ROM (Compact Disc Read-Only Memory) drive or DVD-ROM drive works
similarly to a player in audio/video entertainment systems.
• Optical disc burners, using special software, allow "burning" or writing data onto discs.

2.2.4 INPUT/OUTPUT SYSTEM
 Function: Facilitating communication between the
computer and the outside world
Basic operations:
• Input data
• Output data
Components:
• Input/Output (IO) devices – peripheral devices
• IO Interface Modules

 I/O Interface Module:
• Input/output devices are not directly connected to the CPU but are connected through an I/O interface
module.
• The module has I/O ports, which are also addressed by the CPU.
• Each I/O device connects to the CPU via its corresponding port.

 Input/Output Devices:
• Function: Responsible for converting information from a certain physical form into data
suitable for the computer and vice versa (converting data between the internal and external
environments of the computer).
• Peripheral devices can be categorized into various types:
1. Data input devices: Keyboard, scanner, mouse, etc.
2. Data output devices: Monitor, printer, etc.
3. Storage devices:Various types of disk drives
4. Communication devices: Modem, Bluetooth, wireless
5. Multimedia support devices:Audio and video systems

 Keyboard: Standard input device
• A panel containing keys with various
functions.
• Main key groups:
• Typing keys: Includes letters, numbers, and
special characters.
• Function keys: Includes keys from F1 to F12,
arrow keys for up, down, left, right, and keys
like PgUp, PgDn, Insert, Delete, Home, End.
• Numeric keypad: Includes keys such as
NumLock, CapsLock, and ScrollLock.
 Mouse:
• Includes ball mouse, optical mouse, and
keyboard-attached mouse.
 Scanner:
• Used to scan text, drawings, or
photographs and input them into the
computer as image files.
 Disk drive:
• When reading data from the disk, it
functions as an input device.

 Monitor:
• A standard output device used to display information for users.
• Information is displayed through a method called Memory Mapping.
 Disk Drive:
• When data is written to the disk, it functions as an output device.
 Printer:
• Used to output information onto paper:
• Dot matrix printer (24-pin type), inkjet printer, black-and-white or color laser printer.
 Projector:
• Functions similarly to a monitor, used as a substitute for a screen in meetings, presentations, and teaching
sessions.

2.2.5. SYSTEM INTERCONNECTION (BUSES)
Information is exchanged between the components of a computer or even within a
complex component like the CPU through a communication system known as a bus.
In reality, the bus in a computer is quite complex and is represented by pathways on
circuit boards, slots on the motherboard, and connecting cables.

 Classification of Bus by Function:
1. Control Bus:Transfers information or signals between components, such as from the CPU
to the input/output system (CPU I/O system).
↔
2. Data Bus: Responsible for transmitting data (contents of memory, processing results) from
the CPU to memory or from memory/CPU to input/output devices.This is a bidirectional
bus, typically with a width of 32 bits or 64 bits.
3. Address Bus: Carries the addresses of memory locations when accessing the contents of
that memory or the addresses of ports for devices that the CPU communicates with.
 BusWidth: Refers to the number of wires in the bus that can transmit bits of information
simultaneously (applicable only to address and data buses).

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2.2.6 PERIPHERAL DEVICES
Speakers: Output device for audio.
Music player: Device used for playing music.
Recording device: Device for capturing audio or sound.
Webcam: Camera used for video communication and
streaming.
Joystick: Input device used for gaming and controlling
movement.
Barcode reader: Device for scanning barcodes and reading data.
Biometric device: Device for scanning and recognizing biometric
data (like fingerprints).
Touch screens: Display that allows for user interaction through
touch.
Ports: Connection points for various devices.
Scanner: Device for digitizing documents and images.
Printer: Device for producing physical copies of documents and
images.

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