Computer Hardware and Architecture

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Computer Hardware and Architecture
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• Objectives
• By the end of this session, the student will be
  able to
• Name and define 5 categories of Computer
  Architecture
• Show how these categories inter-relate
• Define the function of input devices
• List and describe the operation of the input
  devices described in the course
• Define the function of output devices
• List and describe the operation of the output
  devices described in the course
• Define Primary Storage
• List 2 types of primary storage
• List the two parts of the CPU
• Describe the function of each part of the CPU
• List the factors that affect processor speed
• Describe how each of these factors affects
  processor speed
• List the 3 operating modes of the Intel processor
• Describe the traits of these modes
• Define Secondary Storage
• List 2 types of secondary storage, give examples
  of each
• List the 3 structures of magnetic secondary
  storage

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Computer Systems

• Definition
• A computer system is hardware that contains
  software to transform data into information.
  This transformation requires four aspects of data
  handling
• Input
• Processing
• Output
• Storage

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Computer Architecture
Computer Architecture The architecture of a
computer can be broken down into 5 categories.
These 5 categories interrelate with each other in
a structured way. Categories The categories of
the architecture of a computer system are
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Input

• Purpose
• The purpose of input is to take data that is
  external to the computer system, and transform it
  into data that is internal to the computer
  system.
• Some of the devices that perform this function
  are
• Keyboard
• Mouse
• Barcode scanner
• Optical Mark Recognition (OMR)
• Optical Character Recognition (OCR)
• Hand-written characters
• Voice recognition
• Touch screens

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Output

• Purpose
• The purpose of output is to take information that
  is internal to the computer system, and transform
  it into information that is external to the
  computer system, and therefore available for the
  user to use.
• Some of the devices that perform this function
  are
• Monitor
• Dot-matrix printer
• Bubble-jet printer
• Laser printer
• Voice

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Primary Storage
Purpose The purpose of primary storage is to
store data for a short period of time while it is
being manipulated. The term 'memory' is also
used when referring to Primary Storage, however
this term also includes forms of memory that are
not Primary Storage.
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Primary Storage, Continued

• Types of memory
• The types of memory are listed below
• RAM (Primary Storage)
• DRAM
• SRAM
• External cache
• ROM (not Primary Storage)
• PROM
• EPROM
• EEPROM

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Processor

• Purpose
• The processor, or Central Processing Unit (CPU)
  is where the computer system performs the
  manipulation of data. Every computer must have
  at least one CPU to function.
• A processor is composed of
• control unit
• Arithmetic / logic unit (ALU)
• Control unit
• The control unit oversees the operation of the
  CPU by performing
• Fetch - get an instruction from memory
• Decode - decide what the instruction means and
  direct the necessary data be moved from memory
  to the ALU
• The combination of Fetch and Decode is called,
  Instruction Time or I-Time

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Processor, Continued

• Arithmetic / Logic Unit
• The ALU performs two classes of operations
• Arithmetic operations
• Logical operations
• The ALU is responsible for
• Execute
• Store
• The combination of Execute and Store is call
  Execution-Time, or E-Time

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Processor, Continued

• Arithmetic operations
• The arithmetic operations performed by the ALU
  are
• Addition
• Subtraction
• Multiplication
• Division
• Older ALUs could only perform addition and
  subtraction. The multiplication and division
  operations were performed through a set of
  instructions.

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Processor, Continued

• Logic operations
• The logic operations, or tests, performed by the
  ALU are
• Equal-to
• Greater than
• Less than
• These can be combined to create an additional
  three tests
• Greater than or equal
• Less than or equal
• Greater than or Less than (not equal)

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Processor, Continued
Machine cycle A machine cycle is the combination
of I-Time and E-Time. The I-Time and E-Time
differs from instruction to instruction,
therefore the machine cycle will also be
different. Diagram of a machine cycle This a
diagram of the steps in a machine cycle
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Processor, Continued

• Processor speed
• The speed of a processor is based on different
  factors
• Clock speed
• Number of instructions
• Internal cache
• Clock speed
• The operations that are taking place in a CPU
  need to be organized to prevent chaos. For
  example, an addition operation cannot be executed
  until the data has finished being read from RAM.
• To control the timing within the CPU, a clock is
  used to synchronize the operations. The clock
  simply supplies a stream of pulses at a very fast
  fixed rate.

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Secondary Storage

• Purpose
• The purpose of secondary storage is to
• retain data and programs while the computer
  system is turned off
• hold data and programs that cannot fit into
  primary storage
• Types of secondary storage
• Secondary storage is composed of two main groups
  of media, within each group are many types of
  secondary storage. The most common are
• Magnetic media
• floppy diskette
• hard disk
• Optical media
• CD-ROM

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Secondary Storage, Continued
Disk layout Disks are flat, round platters housed
in a case that protects their surface from
contamination. Tracks The logical structure of
disk consists of a series of concentric rings,
called tracks. Sectors These tracks are
subdivided into sectors. The Sectors contain the
data.
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Secondary Storage, Continued
Typical capacity The contemporary CD-ROM can
store up to 700MB. Access speed terms There are
common terms used when defining the speed of
operation of a disk Seek Time The time it
takes the Read/Write head to be positioned over a
track Rotational Delay The time it takes for a
sector to rotate under the read/write head
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ICS124 Week2 Data Representation
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• Objectives
• By the end of this session, the student will be
  able to
• Define a Positionally Dependent numbering system
• Give examples of positionally dependent and
  positionally independent numbering systems
• List the digits used in the binary, octal and
  hexadecimal numbering system
• Express each position of significance as the base
  to an appropriate exponent
• List the steps to convert a decimal number to any
  numbering system
• Use the technique to perform conversions of
  decimal numbers to binary, octal and hexadecimal
  numbering systems
• Explain the process of converting from any
  numbering system to the decimal number system
• Use the process to perform conversions of binary,
  octal or hexadecimal numbering systems to the
  decimal numbering system
• List the steps of the short-cut to convert a
  binary number to an octal number
• Use the technique to perform binary to octal
  conversions
• List the steps of the short-cut to convert a
  binary number to a hexadecimal number
• Use the technique to perform binary to
  hexadecimal conversions
• List the steps of the short-cut to convert an
  octal number to a binary number
• Use the technique to perform octal to binary
  conversions
• List the steps of the short-cut to convert a
  hexadecimal number to a binary number
• Use the technique to perform hexadecimal to
  binary conversions
• Define the terms bits, bytes, nibbles and words

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Numbering Systems, Continued

• Decimal numbering system
• The Arabic numbering system is a Decimal
  numbering system. There are three attributes we
  will look at
• The digits of this numbering system are
  positionally dependent.
• It is based on a quantity of 10.
• Contains the digits 0 1 2 3 4 5 6 7 8 9
• Positionally dependent
• Positionally dependent means that the
  significance of a digit is related to where it
  can be found in the number. For example, does
  the digit '1' mean the same thing in these two
  numbers?
• 51
• 163
• These are the same numbers in Roman numerals,
  does the different position of the 'L' character
  change its significance?
• LI
• CLXIII

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Numbering Systems, Continued
Positionally dependent, continued A closer look
at the composition of a decimal number 1492 Is
composed of 1000 400 90 2. Another way of
expressing this is 1492 (1 x 1000) (4 x
100) (9 x 10) (2 x 1) If we take the
multipliers (1000, 100, 10, 1) and express them
as exponents of the base 1000 103 (10 x 10 x
10 - ten multiplied by itself 3 times) 100 10
x 10 102 (10 x 10 - ten multiplied by itself 2
times) 10 101 1 100 1492 (1 x 103) (4
x 102) (9 x 101) (2 x 100)
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Numbering Systems, Continued

• Positionally dependent, continued
• In summary, we can say that a digit's
  significance is dependent on its position within
  the number.
• The more digits that sit to a digits right, the
  more significant the digit
• 88888
• In the above number the '8' that is the rightmost
  digit has less significance than the '8' digit
  that is leftmost.
• Terms such as
• 'Least Significant Digit' (LSD), and
• 'Most Significant Digit' (MSD)
• are used to describe this property.
• As more significant digits are added, the
  exponent is increased by one.
• ... 106 105 104 103 102 101 100

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Numbering Systems, Continued

• General statements
• Some general statements about positionally
  dependent numbering systems, using the Base-10
  numbering system as an example
• There are base digits in the system (base is 10,
  therefore there are 10 digits)
• The digits in the numbering system start at 0 and
  go to base - 1 (base is 10, therefore base - 1 is
  9. Therefore, the digits go from 0 to 9)
• The digits of significance, starting at the
  right, and moving left are
• expressed as an exponent where the base is the
  base of the numbering system- which is how the
  term 'base' comes to be
• the exponents start at 0 and increment by 1 for
  each digit of significance

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Numbering Systems, Continued

• Binary numbering system
• The binary numbering system has three attributes
  that we will look at
• The digits of this numbering system are
  positionally dependent.
• It is based on a quantity of 2.
• Contains the digits 0 1
• Positionally dependent
• The definition remains the same as in the decimal
  numbering system. However, lets take a closer
  look at the composition of a binary number.
• 1101 (this number is not one thousand one
  hundred and one)
• Looking back at the base-10 numbering system, as
  more significant digits were added, the exponent
  of the base increased by one.
• Using this a model, then the significance of the
  digits within the binary numbering system would
  be
• ... 26 25 24 23 22 21 20

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Numbering Systems, Continued

• Octal numbering system
• The octal numbering system has three attributes
  that we will look at
• The digits of this numbering system are
  positionally dependent.
• It is based on a quantity of 8.
• Contains the digits 0 1 2 3 4 5 6 7
• Positionally dependent
• The definition remains the same as in the decimal
  numbering system. However, lets take a closer
  look at the composition of an octal number.
• 571
• Looking back at the base-10 numbering system, as
  more significant digits were added, the exponent
  of the base increased by one.
• Using this a model, then the significance of the
  digits within the octal numbering system would
  be
• ... 86 85 84 83 82 81 80

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Numbering Systems, Continued

• Hexadecimal numbering system
• The hexadecimal numbering system has three
  attributes that we will look at
• The digits of this numbering system are
  positionally dependent.
• It is based on a quantity of 16.
• Contains the digits 0 1 2 3 4 5 6 7 8 9 A B C D
  E F
• Positionally dependent
• The definition remains the same as in the decimal
  numbering system. However, lets take a closer
  look at the composition of a hexadecimal number.
• 1492
• Looking back at the base-10 numbering system, as
  more significant digits were added, the exponent
  of the base increased by one.
• Using this a model, then the significance of the
  digits within the hexadecimal numbering system
  would be
• ... 166 165 164 163 162 161 160

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Converting between bases
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Converting between bases, continued

• Converting from decimal
• The process is the same for any base when
  converting from decimal. The digits created will
  begin at the least significant digit and work
  its way to the left (to the most significant
  digit).
• divide the decimal number by the base, getting
  quotient and remainder
• the remainder is the digit in the new numbering
  system (written to the left of the previous
  number)
• take the quotient as a decimal number and repeat
  from step 1, until the quotient is 0

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Converting between bases, continued
Converting to decimal The process is the same for
any base when converting to decimal, and is
easier than converting from decimal to a
base. If 'b' is the base (ie. 2, 8, 16), 'd' is
the digit, and 'e' is the exponent of the base,
then the formula n Sdebe e0 will perform the
conversion. This means dnbn . . . d3b3
d2b2 d1b1 d0b0
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Converting between bases, continued
Converting to decimal, continued n Sdebe gt
dnbn . . . d3b3 d2b2 d1b1
d0b0 e0 Assuming base-8, and the digits 6548,
then 6x82 5x81 4x80 (6 x 64) (5 x 8)
(4 x 1) 384 40 4 42810
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Converting between bases, continued

• Converting from binary
• There are many occurrences when you will convert
  from binary to a base other than 10, or vice
  versa. There are short-cuts for these
  conversions.
• Binary to octal
• To convert from binary to octal
• Start at the least significant bit, and place the
  bits into groups of three bits
• Convert each of these groups (independent of each
  other) into octal digits
• For example, convert 10100111112 to octal
• 1-010-011-111
• 12378

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Converting between bases, continued

• Binary to hexadecimal
• To convert from binary to hexadecimal
• Start at the least significant bit, and place the
  bits into groups of four bits
• Convert each of these groups (independent of each
  other) into hexadecimal digits
• For example, convert 10100111112 to hexadecimal
• 10-1001-1111
• 29F16

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Converting between bases, continued
Octal to binary To convert from octal to binary,
the reverse process is applied. Convert each
octal digit into groups of three bits For
example, convert 32158 to binary 011-010-001-101
110100011012
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Converting between bases, continued
Hexadecimal to binary To convert from hexadecimal
to binary, the reverse process is applied.
Convert each hexadecimal digit into groups of
four bits For example, convert 10AD16 to
binary 0001-0000-1010-1101 10000101011012
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Converting between bases, continued
Summary The following chart summarizes the
techniques to use based on the conversion
desired
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Binary and computers
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Binary and computers, continued

• Bits, Bytes, Nibbles and Words
• We have defined a bit as a single binary digit,
  that is either a '0' or a '1'. There are other
  terms used when dealing with binary numbers that
  is based on the number of bits in the number.
  These terms are
• Bytes
• Nibbles
• Words
• Bytes
• In computers we look at bits in groups of eight.
  Early computers could not hold binary number that
  contained more than eight digits (bits). A group
  of eight bits is referred to as a byte.
• Remember the aggregate terms for memory? KB, MB
  and GB? The 'B' represented bytes (8 bits).
  Sometimes you will see Kb or Mb. This is an
  aggregate of bits. Be wary of this and perform
  conversions as required.
• That is why on the previous slide I said 32MB RAM
  would contain over 268 million bits (switches).

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ICS124 Week3 Data Representation
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• Objectives
• By the end of this session, the student will be
  able to
• Add two binary numbers together correctly
• List two means to represent signed binary numbers
• Construct signed binary numbers based on the two
  representations
• Show an alternative way to represent subtraction
  of two numbers
• Perform binary subtraction through the use of
  twos complement
• List the three components of a floating-point
  number
• Define the criteria for Normalized Format when
  expressing a floating point number
• Report on the Normalized Format criteria that has
  not been met when looking at a floating point
  number
• Categorize the various numeric data types of the
  C language
• Appreciate that the C language has multiple ways
  to represent numbers
• List 3 coding schemes used by computers
• Apply the coding scheme tables to convert between
  characters and bit strings
• Define the term 'collating sequence' in relation
  to the coding schemes
• Predict the outcome of sorting data using the
  coding schemes
• Describe the advantage of using Packed Decimal to
  store numbers
• Convert decimal numbers to signed Packed Decimal
  format

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Binary math
Binary math This section will introduce you to
addition and subtraction of binary
numbers. Addition Remember how we add in
base-10 1 1 lt--- carry
297 194 ------- 491 In binary we only have
four possible results 02 02 02 12 02
12 12 12 102 (this is were we carry the
12) 12 12 12 112 (if we had carried a
one, we will need to again)
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Binary math

• Addition, continued
• 02 02 02
• 12 02 12
• 12 12 102 (this is were we carry the 12)
• 12 12 12 112 (if we had carried a one, we
  will need to again)
• On a small scale, add these two binary numbers
  together
• 1 1
• 0110
• 0111
• --------
• 1101
• If we convert these to decimal, we see that we
  are correct
• 01102 is 610
• 01112 is 710
• 11012 is 1310

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Binary math
Example 02 02 02 12 02 12 12 12 102
(this is were we carry the 12) 12 12 12
112 (if we had carried a one, we will need to
again) Perform this calculation 11012
101112 Prove that the calculation is correct by
converting all binary numbers to decimal.
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Binary math, continued

• Signed and unsigned numbers
• So far the numbers we have been dealing with are
  all positive integers. However, there exists
  such things as negative numbers, as in 297
  (-194) 103
• Unfortunately, computers are aware of only two
  states, on and off. These states are used to
  represent the bits in the binary number system.
  There is no third state to represent negative
  bits.
• A means to differentiate between positive numbers
  and negative numbers is required.
• There are two schemes used to differentiate
  between positive and negative numbers
• Sign and Magnitude
• Twos complement
• In this class when working with signed binary
  numbers, work in multiples of eight-bits. You
  may discard overflow bits.

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Binary math, continued
Sign and magnitude The simplest means to
differentiate between positive and negative
numbers is to reserve one of the bits of a binary
number to indicate sign. The most significant
bit has been chosen for this purpose. This
leaves one less bit to represent the number- for
example 7 bits or 15 bits. IF the sign bit is
'0' THEN the number is positive IF the sign bit
is '1' THEN the number is negative For
example 0101 11012 9310 1101 11012
-9310 Since (93) (-93) 0 then 010111012
110111012 should be 000000002 Try it.
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Binary math, continued

• Twos complement
• Twos complement, or 2s complement, is very
  similar to the scheme that uses just a sign bit.
  However, as we shall see when we perform
  subtraction, this scheme is better.
• To calculate the 2s complement of a number
• flip the bits (1 -gt 0, 0 -gt 1) this stage is also
  referred to as one's complement
• add 1
• For example,
• 010111012 becomes
• 101000102 lt--- bits flipped
• 12
• ---------------
• 101000112
• So 010111012 is 9310, and
• 101000112 is -9310

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Binary math, continued
Twos complement, continued To take a negative
number in 2s complement and convert into a
positive number, perform the 2s complement
operation again. For example, 101000112
(-9310)becomes 010111002
12 ----------- 010111012 So 010111012 is
9310, and 101000112 is -9310
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Binary math, continued
Twos complement, continued If we wish to perform
9310 - 9310, we could instead perform 9310
(-9310). In binary it would be 010111012
101000112 ------------ (1)000000002 The
overflow 12 is ignored. This is also what
happens in the CPU, and it knows when to ignore
the overflow 12 bit as well.
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Floating Point Numbers
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Floating Point Numbers, continued
Base Since are dealing with a binary machine, the
base is always 2. There is no need to store it
in memory. Mantissa The mantissa is stored in
sign and magnitude format and is normalized,
HOWEVER, there is a slight variation regarding
normalization. The binary mantissa is in the
range of 1.00000000000000000000000
to 1.11111111111111111111111 1.0 lt M lt
2 Since the mantissa ALWAYS starts with a '1',
the leading 1 is never stored, it is assumed to
be there. Therefore, 1.00011111111111111111101 wo
uld be stored as 00011111111111111111101 This is
the normalized format for the storage of floating
point binary numbers.
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Floating Point Numbers, continued
Mantissa, continued Since we are dealing with
values to the right of the 'radix point'
(commonly called a decimal point in the decimal
numbering system), the digit exponents are
negative In Decimal 10-1, 10-2, 10-3, 10-4,
10-5, 10-6... 1/10, 1/100, 1/1000, 1/10000,
1/100000 0.1, 0.01, 0.001, 0.0001, 0.00001,
0.000001.... In Binary 2-1, 2-2, 2-3, 2-4, 2-5,
2-6... 1/ 2 1/ 4 1/8 1/16 1/32 1/64....
0.5, 0.25, 0.125, 0.0625, 0.03125,
0.015625... therefore 1.12 1x20 1x2-1 110
1/ 210 3/210
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Floating Point Numbers, continued

• Exponent
• The exponent is stored in 'Excess 127' format.
  To get the exponent, you subtract 127 from the
  stored value.
• Therefore, if the value stored is 120, the
  exponent would be -7
• There are two 'special'cases for the exponent
• 0 - represents 'Exactly zero' (as opposed to a
  number that looks like zero because it has lost
  its precision)
• 255 - represents infinity
• A portion of the excess-127 table
• 00000000 0 - exactly 0
• ...
• 01111101 125 - -2
• 01111110 126 - -1
• 01111111 127 - 0
• 10000000 128 - 1
• 10000001 129 - 2
• ...
• 11111111 255 - infinity

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Floating Point Numbers, continued
Layout of floating point number The layout is as
follows Sign bit - 1 bit Exponent - 8
bits Mantissa - 23 bits
32 bits Seee-eeee-eMMM-MMMM-MMMM
-MMMM-MMMM-MMMM 0100-0000-0000-0000-0000-0000-0000
-0000 210
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Floating Point Numbers, continued
Layout of floating point number,
continued Seee-eeee-eMMM-MMMM-MMMM-MMMM-MMMM-MMMM
1100-0011-1001-0110-0000-0000-0000-0000 Sign is
negative Exponent 10000111 135
135 - 127 8
represents 28 Mantissa 1.001011 1
1/8 1/32 1/64 75/64 -75/6410 x 28
-300.0010
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Coding Schemes
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Coding Schemes, continued
6-bit Binary Coded Decimal, continued Character Co
de Character Code A 11 0001 S 01
0010 B 11 0010 T 01 0011 C 11
0011 U 01 0100 D 11 0100 V 01
0101 E 11 0101 W 01 0110 F 11
0110 X 01 0111 G 11 0111 Y 01
1000 H 11 1000 Z 01 1001 I 11
1001 0 00 1010 J 10 0001 1 00
0001 K 10 0010 2 00 0010 L 10
0011 3 00 0011 M 10 0100 4 00
0100 N 10 0101 5 00 0101 O 10
0110 6 00 0110 P 10 0111 7 00
0111 Q 10 1000 8 00 1000 R 10
1001 9 00 1001
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Coding Schemes, continued
ASCII, continued The bit
pattern for the letter 'Z' would be 1011010
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Coding Schemes, continued
EBCDIC
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Packed Decimal
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Packed Decimal, continued

• Packed Decimal
• How is the number 57398 represented in
• 6-bit BCD 000101 000111 000011 001001 001000
• ASCII? 00110101 00110111 00110011 00111001
  00111000
• EBCDIC? 11110101 11110111 11110011 11111001
  11111000
• In Packed decimal each nibble is used to
  represent a digit between 0 and 9. The
  right-most nibble stores the sign of the number.
  A leading zero may be required when representing
  the number.
• The sign nibble is
• 1100 for positive numbers
• 1101 for negative numbers
• How would 57398 be represented in packed decimal?

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ICS124 Week4 Introduction to Networking
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• Objectives
• By the end of this session, the student will be
  able to
• Describe how data is represented for transmission
• Decode a bit pattern from transmitted data
• List the two methods modems use to modulate a
  carrier wave
• Diagrammatically represent data streams using the
  two modulation types
• Define Bandwidth
• Rank various communications types in order of
  bandwidth
• List the two methods of modem synchronization
• Contrast the modem synchronization methods in
  relation to speed and content
• List the three modes of data flow
• Provide an analogy of each of these methods to
  demonstrate how each method functions
• List three ways users can interact with a
  computer system
• Distinguish each of these through discussion of
  how the data is accessed, and where the data is
  processed
• List the three network topologies
• Diagram each of the topologies and show where
  each will fail
• List four components of a network
• Describe the purpose of each component
• Define the term protocol

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Introduction to Networking, continued

• How data is represented
• Computers store data in binary form. We have
  looked at the storage of binary data in RAM and
  ROM as the states of switches
• a switch turned on represents a 1 bit
• a switch turned off represents a 0 bit
• This binary form can also be represented using
  electrical pulses, where
• the presence of a voltage represents a 1
• the absence of a voltage represents a 0
• 5V-
• 0V-
• In this waveform do we have
• 00101011001100? or
• 0000110011001111000011110000? or
• something else?

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Introduction to Networking, continued
How data is represented, continued The only way
to know is by measuring the waveform against
time 1 0 seconds IF we are transmitting at
a rate of 1 bit per second, then the bit stream
would be 00101011001100 2 bits per second, then
the bit stream would be 00001100110011110000111100
00 Serial port During the first week we briefly
mentioned the serial port on a PC. Its function
is to transmit or receive one bit at a time. The
typical maximum rate of serial ports on PCs is
115,400 bits per second, or 115,400 baud The
serial port is only able to transmit data about
15.3m (50') before the electrical properties of
the wire seriously degrade the signal (at 20Kbps).
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Introduction to Networking, continued

• Modems
• A means to send data over longer distances has
  been devised using older technologies (such as
  the phone) and newer technologies that are
  specifically designed for computer equipment.
• A modem is a device that modulates a digital data
  onto an analog signal, and demodulates the analog
  signal, providing digital data.
• An analog signal, called a carrier, can be
  modulated in two basic ways
• amplitude
• frequency

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Introduction to Networking, continued

• Modems, continued
• amplitude - two wave-forms with different
  amplitude
• The crests and troughs line up.
• The height, amplitude, of the waves are different
  (12)

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Introduction to Networking, continued

• Modems, continued
• frequency - two wave-forms with different
  frequency
• The amplitude of the waves are the same
• The number of repetitions per unit time,
  frequency, are different (11.5)

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Introduction to Networking, continued
Modems, continued By altering the amplitude or
the frequency of the carrier wave, information
can be transmitted. These are how the two types
are radio transmissions are classified. The AM
radio uses Amplitude Modulation to transmit the
audio, and the FM radio uses Frequency
Modulation. This is an example of how digital
information may be transmitted on a carrier
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Introduction to Networking, continued
Asynchronous/Synchronous transmissions A
representation of the two transmissions methods
is Because there are no start and stop
bits for each character in synchronous
transmission, it is faster than asynchronous
transmissions. Asynchronous transmission
increases the number of bits sent by a factor of
10/8 (1.25) assuming 8 bits, no parity, 1 stop
bit. To send 1KB of data 8192 data
bits 2048 start and stop bits 10240
total bits sent The serial port on a PC is
asynchronous.
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Introduction to Networking, continued

• Data flow directions
• The data in a communications link can flow in
  one-way or two-way directions. This is defined
  by the terms
• Simplex
• Half-duplex
• Full-duplex
• Simplex
• The data flows in one direction only. This is
  like listening to the radio in your car, all the
  information flows to you. You don't send
  information back through the radio.
• Half-Duplex
• The data flows in two directions, but only not
  simultaneously. This is like a polite
  conversion. The first person talks while the
  second person listens. When the first person
  stop talking the second person is then free to
  talk, while the first person listens.

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Introduction to Networking, continued

• Network topologies
• A computer can be connected to only one other
  computer, or it can be connected to a network of
  computers. The network can be laid out in
  different arrangements, or topologies.
• The topologies that we will look at are
• Star network
• Ring network
• Bus network
• There are variations on these networks.
• Star network
• A central computer is responsible for controlling
  all activity on the network. The workstations
  communicate with the central computer for all
  requests.
• The problem with this arrangement is if the
  central computer fails, the network fails. Also,
  the speed of the network will be restricted by
  the speed of the central computer.

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Introduction to Networking, continued
Ring network The computers are arranged in a
ring, where a computer only talks to the computer
beside it. The problem with this arrangement is
that if one computer fails, then the ring is
broken and the network fails. The advantage of
the ring network is that there is no risk that
messages will collide with each other (see Bus
Network). Bus network The computers are all
connected to a common line. Any computer can
talk to any other computer in this network. The
advantage of the bus network is that if any
computer fails, the network continues to operate.
The problem with this network is if more than
one machine sends a message at the same time
(collision). The problem of collisions is why
the ring network can support more computers than
the bus network.
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Introduction to Networking, continued
Network topologies, continued This is a diagram
of each of the network topologies
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Introduction to Networking, continued

• Classification of networks
• A network can be classified as either
• Wide Area Network (WAN)
• Local Area Network (LAN)
• A WAN refers to a network that spans a large
  geographic area, from the size of a city to a
  global network.
• A LAN refers to a network that spans a small
  geographic area, from an office to complex of
  buildings such as a school campus.
• Components of networks
• There are various devices that are part of
  connecting computers and networks together. The
  short list discussed here is
• Network Interface card
• Bridge
• Gateway
• Router

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Introduction to Networking, continued
Network Interface Card The Network Interface Card
(NIC) is used to connect a computer to a
particular type of network. An Ethernet NIC will
not run on a Token Ring network, and vice
versa. The wiring of the network is connected to
the NIC. Bridge A bridge is a means to connect
two similar networks. If a message is destined
for a computer on another network that is also
connected to bridge, the bridge will forward the
message onto the second network Gateway A
gateway is used to connect two dissimilar
networks. Some form of protocol conversion may
take place. Router A router is very much like a
bridge, and can even incorporate gateway
functions. However, it is more complex in that
it looks for ways to send traffic through a
network of networks, and find the best route for
the message.
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Introduction to Networking, continued
Sample network This is a diagram of the various
components of the network
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Introduction to Networking, continued
Protocols A protocol is a set of rules by which
communications are controlled. If a set of
computers use the same protocol, then they will
be able to communicate with each other. If the
protocol is standardized internationally, then
regardless of the computer system, and provided
the protocol was properly implemented then the
computer system will be able to communicate with
any other computer system that implements the
same protocol. The protocol for the Internet is
TCP/IP (Transmission Control Protocol / Internet
Protocol). Some other protocols are IPX/SPX,
NetBios, IEEE802.2, DECnet, AppleTalk
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Introduction to Networking, continued

• Protocols, continued
• There are protocols that allow for the TCP/IP
  protocol to be used over a serial connection (a
  modem). Two are mentioned here
• SLIP
• PPP
• SLIP
• Is an acronym for Serial Line Interface Protocol.
  This is an older protocol that supports TCP/IP
  only. The IP address of the PC as well as the IP
  address of the server that you are dialing into
  must be known. (more on IP Addresses later).
• PPP
• Is an acronym for Point-to-Point Protocol. This
  newer protocol supports TCP/IP as well as other
  protocols. Furthermore, multiple protocols can
  be running simultaneously through PPP (the term
  protocol stack refers to the protocols that are
  available/running on a machine). PPP will
  automatically configure itself during the
  connection to determine what IP address to use
  for the PC as well as the server.

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Introduction to Networking, continued

• TCP/IP Applications
• There are two TCP/IP applications that are
  commonly used. It is important to note that
  these applications are specific to TCP/IP
  networks. They are not defined for other
  protocols.
• The applications are
• telnet
• ftp
• Telnet
• Telnet is a terminal emulation package. This
  utility will be used in our labs when connecting
  to the RS/6000 (UNIX). Telnet will be configured
  to emulate a VT100 terminal.
• FTP
• FTP is an acronym for File Transfer Protocol.
  This application will also be used in our labs to
  transfer data between the PC and the RS/6000.

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Introduction to Networking, continued
IP Addresses In order to determine where a packet
needs to be sent, or where to send a response,
addresses are used. A TCP/IP address is normally
displayed in 'dotted-decimal' notation. The
address consists of 4 numbers (each between 1 and
254) separated by a period. For example
142.204.57.135 (the 0 and 255 values have
special meaning that will not be discussed
here) The following is an Instructor-led
in-class exercise to see these addresses in
action
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Browsers and the Internet
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Browsers and the Internet, continued
Browsers This is a diagram of a browser with the
parts labeled
Welcome Banner
Pull-down menus
Browser control panel
Buttons
Address window
Browser display window
Status line
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Browsers and the Internet, continued
URL URL is an acronym for Uniform Resource
Locator. It is the name given to a particular
site or page within a site. The URL is composed
of The domain is structured as a
hierarchy of nodes, like a company's
organizational chart. At the top of the Internet
is the root node (symbol is '.', but nobody uses
it). The next level is the top-level domains
such as .com .ca .net. The last levels are used
to identify the company or name and then the
server or partition.
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Browsers and the Internet, continued
Frames Frames are means to subdivide the browser
display window into multiple, independently
control windows. In this example, there are five
frames in the browser display window.
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Browsers and the Internet, continued
Plug-ins Plug-ins are additional software modules
that can be hooked into the browser to enhance
its functionality. Some common plugins are
RealPlayer, Adobe Acrobat Reader,
Quicktime. To find out what plugins are
installed in a browser enter the following
command in the address window aboutplugins
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Browsers and the Internet, continued
Java Java is a programming language developed by
Sun Microsystems. It is very popular on the
Internet because it is platform
independent. Platform independent When a program
is written, it is usually targeted to run on a
specific operating system. For example if you
take an application that was written for the Mac
and try to run it on a Windows95 PC, it will not
run. Java is different, in that the Java code
can run on any machine IF it has a Java Virtual
Machine installed. The JVM is written for a
specific operating system. The Java code is
written to run on the JVM. Therefore any Java
programs can run any operating system.
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Browsers and the Internet, continued
Search engines The Internet is a vast landscape
(cyberscape?) of computers with useful and
useless data / information / misinformation,
etc. To try and find anything on the Internet is
an impossible task without some means to sift
through the sites and categorize the data. A
search engine provides this functionality
(assuming that you can find a site for a search
engine). Knowing how some of the search engines
behave will help you make intelligent decisions
as to which engine to use for which
purpose. Some engines try to catalog all the
words it finds on the sites, others are research
based where people sift though the sites and
catalog the sites using predefined criteria.
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Browsers and the Internet, continued

• Search engine types
• In general there are three classes of 'Search
  Engines'
• Directory
• Human researchers organize sites by content
  categories
• Search engine
• Software that resides at a site and uses a set of
  rules to automatically catalog internet sites
• Metasearch site
• Software that searches 'search engines'

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ICS124 Week 5 Software Introduction to UNIX
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93

• Objectives
• By the end of the session the student will be
  able to
• List the 5 types of application software
• Give examples of each type of application
  software
• Classify the application software as
  Task-oriented, Office Suite or Business
• List the two classifications of Systems Software
• Give examples of operating system utilities
• Describe the interaction of the hardware,
  operating system, application software and user
  within a computer system
• List the four attributes that describe the
  capabilities of an operating system
• Define each of the attributes that describe the
  capabilities of an operating system
• List two methods to manage memory in a computer
  system
• Describe how each method works, and provide
  advantages and disadvantages of each method
• List the components of a UNIX command
• Construct a UNIX command
• Describe the structure of the UNIX file system
• Determine the name of a directory, or describe
  the position of a directory within the UNIX file
  system
• List the rules for naming directories and files
• List the three classes of file permissions and
  the membership for each class
• List the three permissions for each class, and
  how it behaves differently for files and
  directories

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Software
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(No Transcript)
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Software, continued

• Software
• Software is what makes the sophisticated hardware
  so powerful. The hardware may as well be a
  paper-weight without software.
• Software is a set of instructions in the language
  of the processor. This language is not readable
  by humans (typically).
• The instructions will consist of
• op-codes (operation codes) and,
• operands (sometimes)
• Op-codes
• The op-codes are fetched and decoded by the
  Control Unit, and executed by the ALU.
• Operands
• The operands are either scalar data (a fixed
  number, such as 5) or a memory address where data
  is stored. These are also fetched by the Control
  Unit for use by the ALU.

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Software, continued
Machine language for Motorola 6809 (8-bit
CPU) 4F 97 13 96 12 27 09 4A 97 12 96 13 9B 11
20 F1 3E 02 05 op-code operand data The above
program multiplies two numbers by repeated
addition. i.e. 5 x 2 2 2 2 2 2
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Software, continued

• Application Software
• By providing different sets of instructions to
  the computer, the hardware can be instructed to
  perform very different tasks such as word
  processing to weather prediction.
• Application example
• Assuming the application is a spreadsheet. A
  user enters data at the keyboard. The
  spreadsheet software stores these values as
  numbers or text or formulas in memory. The
  formulas require calculations be performed based
  on data elsewhere in memory (on the spreadsheet).
  While all this is taking place, a constant
  update of what is happening is sent to the user
  through the monitor.
• Task oriented software
• Software that performs a specific function that
  can be customized by the user, is referred to as
  Task Oriented Software. Examples of task
  oriented software are
• Word processing
• Spreadsheets
• Database management
• Graphics
• Communications

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Software, continued
Word processing Word processing software is used
for writing memos, letters, reports,
etc. Documents can be created, saved and edited.
This type of software replaced the need for
typing pools at companies. Spreadsheets Spreads
heets are a means to manipulate rows and columns
of numbers and formulas. Historical data can be
tracked in a spreadsheet, such as household
expenses paid. Planning and forecasting analysis
can also be performed through a spreadsheet
(what if? analysis). Possible future outcomes
can be calculated by manipulating values in the
spreadsheet. Recalculating a paper-based
spreadsheet can be a tedious, time-consuming
task. The electronic spreadsheet speeds up the
process.
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Software, continued
Database management Database management software
is a means to track and report on inter-related
data. A database consists of characters or
numbers that are stored in fields.
Inter-related fields are grouped into records.
Inter-related records are stored in tables.
Tables are stored in database files on secondary
storage. Databases can be searched for specific
data or data can be summarized to derive useful
information. For example, here are two tables of
information employees departments empno
name deptno salary deptno name 0001 John
Smith 10 40000 10 Marketing 0002 Jane
Doe 10 45000 20 Sales 0003 Frank
Tank 20 30000 30 Manufacturing 0004 Tweedle
Dee 20 29500 40 Executive 0005 Tweedle
Dum 20 35000 0006 Jill Jelly 30 38000
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Software, continued
Graphics This class of software is used to depict
information pictorially, such as through maps,
charts and graphs. Presentation software is a
type of Graphics software used to prepare
presentations that are either transferred to
acetate (overhead transparencies) or are
projected directly onto a screen from a
computer. Communications Communications software
is used to interconnect two or more computers. A
package such as HyperTerminal allows a computer
to connect to another either directly through a
serial connection or through a phone line by use
of a modem. The nature of the connection will
depend on the software running on the remote
computer. A browser, as discussed last week, is
used to navigate through the Internet, and
display the information that is stored on the
servers.
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Software, continued

• Office suite
• Office suite software combines many of the task
  oriented software into a group of packages that
  are able to share data between themselves. For
  example, a spreadsheet could be embedded into a
  document that is being prepared on a word
  processor.
• The