305171 Computer Programming

Rattapoom WaranusastDepartment of Electrical and Computer EngineeringFaculty of Engineering, Naresuan University

A COMPUTER is an electronic device that can:– Receive information– Perform processes– Produce output– Store info for future use.

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Personal computers (PC)

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Mobile devices

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Game consoles

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Servers

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Mainframe computers

IBM zEnterprise

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Super computers

Fujitsu’s K - Computer

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Embedded systems

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Robots

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Hardware Software

Peopleware

PCMainframeMobileEtc.

ProgrammerSystem AnalystUserAdministratorEtc.

OSApplicationsFirmwareContentEtc.

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Input(Input Devices)

Process(CPU)

Output(Output Devices)

Storage(Memory)

Feedback

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Arithmetic and logic unit (ALU)– performs arithmetic and logical operations

Control unit– controls the flow of data through the

processor, and coordinates the activities of the other units within it

Registers– small amount of storage available on the CPU

whose contents can be accessed more quickly than storage available elsewhere

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Main (primary) memory– Stores programs and data while computer is

running. Main memory is fast and limited in capacity. The CPU can only directly access information in main memory.

– Random Access Memory (RAM)– Read-Only Memory (ROM)

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• Size :• Kilobyte KB 210 ~103

• Megabyte MB 220 ~106

• Gigabyte GB 230 ~109

• Terabyte TB 240 ~1012

• Petabyte PB 250 ~1015

• Exabyte EB 260 ~1018

• Zettabyte ZB 270 ~1021

• Yottabyte YB 280 ~1024

Memory mappingAddress Values0000 00010002......

..

FFFF

1 0 1 1 1 0 0 1

0 0 0 0 1 1 1 1

1 1 1 0 0 0 1 1

0 0 1 0 0 1 0 018

External (secondary) memory– Holds information too large for storage in

main memory. – Information on external memory can only be

accessed by the CPU if it is first transferred to main memory.

– It retains information when the computer is switched off.

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BUSClock

ALU

CURegiste

rs

CPU

Main Memor

y

VDO controll

er

Diskcontroll

er

I/O ports

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A clock signal is a signal generated by quartz crystal circuit that oscillates between a high and a low state and is utilized to coordinate actions of circuits.

Clock rate is measured in cycles/sec (Hertz ).

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Problem oriented language level

Assembly Language

Operating System

Instruction Set Architecture

Micro-architecture level

Digital Logic Level

Level 5

Level 3

Level 2

Level 1

Level 0

Level 4

User

Translation (compiler)

Translation (assembler)

Circuits

Partial interpretation (operating system)

Interpretation (microprogram) or direct execution

Hardware

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The interesting objects at this level are gates; Each gate has one or more digital inputs

(signals representing a 0 or 1) and computes as output some simple function of these inputs, such as AND or OR;

A small number of gates can be combined to form a 1-bit memory, which can store a 0 or 1;

The 1-bit memories can be combined in groups of, for example, 16, 32 or 64 to form registers.

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A collection of 8-32 registers that form a local memory and ALU

The registers are connected to the ALU to form a data path over which the data flow;

The operation of the data path may be controlled by a microprogram, directly by hardware, or even by software.

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The ISA level is defined by the machine’s instruction set

This is a set of instructions carried out interpretively by the microprogram or hardware execution sets;

Machine languages – Strings of numbers giving machine specific

instructions

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The Operating System Machine (OSM) level is a complete set of instructions available to application programmers. This includes all ISA level instructions and a new set of instructions that the operating system adds called system calls.

The OSM level is always interpreted. For instance, if reading data from file, the operating system carries it out step by step.

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This level is really a symbolic form. This level provides a method for people to write programs

for levels 1, 2 and 3 in a form that is more readable. Programs in assembly language are first translated to

level 1, 2 or 3 language and then interpreted by the appropriate virtual or actual machine.

The program that performs the translation is called an assembler.

Example:LOAD R1, #FFFFADD R2,R1MOV R3,R2

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This level usually consists of languages designed to be used by applications programmers.

These languages are generally called higher level languages, for examples: C, C++, Java, BASIC, LISP, Prolog, Pascal, FORTRAN, COBOL, etc.

Programs written in these languages are generally translated to Level 3 or 4 by translators known as compilers, although

occasionally they are interpreted instead.

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Computers use binary numbers internally because storage devices like memory and disk are made to store 0s and 1s. A number or a text inside a computer is stored as a sequence of 0s and 1s. Each 0 and 1 is called a bit, short for binary digit. The binary number system has two digits, 0 and 1.

Binary numbers are not intuitive. When you write a number like 20 in a program, it is assumed to be a decimal number. Internally, computer software is used to convert decimal numbers into binary numbers, and vice versa.

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The digits in the decimal number system are 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9. The value that each digit in the sequence represents depends on its position. A position in a sequence has a value that is an integral power of 10.

We say that 10 is the base or radix of the decimal number system. Similarly, the base of the binary number system is 2 since the binary number system has two digits and the base of the hex number system is 16 since the hex number system has sixteen digits.

5892 = 5 x 103 + 8 x 102 + 9 x 101 + 2 x 100

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A positional number system Has only 2 symbols (0 and 1), so that base = 2 The maximum value of a single digit is 1

(base – 1) The maximum value of N digits is 2N-1 Used mostly in computer system

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5 digits binary can store number up to 25-1 = 32-1 = 31

Example101012 = (1x24)

+ (0x23) + (1x22) + (0x21) + (1x20)= 16 + 0 + 4 + 0 + 1 = 2110

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A positional number system Has only 8 symbols (0, 1, 2, 3, 4, 5, 6, 7), so that

base = 8 The maximum value of a single digit is 7

(base – 1) The maximum value of N digits is 8N-1 Used mostly in computer system

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Example20578 = (2x83)

+ (0x82) + (5x81) + (7x80)= 1024 + 0 + 40 + 7 =107110

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A positional number system Has only 16 symbols (0-9, A, B, C, D, E, F), so

that its base = 16 The maximum value of a single digit is 15 (F)

(base – 1) The maximum value of N digits is 16N-1 Used mostly in computer system

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Example1AF16 =

(1x162) + (10x161) + (15x160)= 256 + 160 + 15 = 43110

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Method1. Determine the column (positional) value of

each digit.2. Multiply the obtained column values by the

digits in the corresponding columns.3. Calculate the sum of these products.

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Division-Remainder Method1. Divide the decimal number by the value of the

new base.2. Record the remainder from step 1 as the right

most digit of the new base number3. Divide the quotient of the previous divide by the

value of the new base.4. Record the remainder from step 3 as the next digit

(to the left) of the new base number.5. Repeat step 3 and 4 until the quotient become 0,

the last remainder will be the most significant digit of the new base number.

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Example95210 = ?8

Solution8 )952 Remainders)119 0)14 7)1 6 0 1

Hence, 95210 = 016708

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Example95210 = ?16

Solution16)952 Remainders)59 8)3 11 0 3

Hence, 95210 = 3B816

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Method1. Convert the original number to a decimal

number2. Convert the decimal number that obtained

on in step 1 to the new base number

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Method1. Divide the digits into groups of three

starting from the right.2. Convert each group of three binary digits to

one octal digit using the method of binary to decimal conversion.

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Example11010102 = ?8

Solution1. Divide the binary into groups of three digits

001 101 0102. Convert each group into one octal digit

0012 = 0x22 + 0x21 + 1x20 = 1

1012 = 1x22 + 0x21 + 1x20 = 5

0102 = 0x22 + 1x21 + 0x20 = 2

Hence, 11010102 = 1528

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Method1. Convert each octal digit to 3 binary digits.2. Combine all the resulting binary groups into

a single binary number.

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Example5628 = ?2

Solution1. Convert each octal digit to 3 binary digits.

58 = 1012 68 = 1102 28 = 0102

2. Combine all the resulting binary groups into a single binary number. 5628 = 101 110 010 2

Hence, 5628 = 1011100102

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Method1. Divide the digits into groups of four starting

from the right.2. Convert each group of four binary digits to

one hexadecimal digit using the method of binary to decimal conversion.

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Example1111012 = ?16

Solution1. Divide the binary into groups of four digits

0011 11012. Convert each group into one hexadecimal digit

00112 = 0x23 + 0x22 + 1x21 + 1x20 = 3

11012 = 1x23 + 1x22 + 0x21 + 1x20 = 13 = D

Hence, 1111012 = 3D1647

Method1. Convert each hexadecimal digit to 4 binary

digits.2. Combine all the resulting binary groups into

a single binary number.

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Example2AB16 = ?2

Solution1. Convert each hex digit to 4 binary digits.

216 = 00102 A16 = 10102 B16 = 10112

2. Combine all the resulting binary groups into a single binary number. 2AB16 = 0010 1010 1011 2

Hence, 2AB16 = 0010101010112

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All information that is processed by computers is converted in one way or another into a sequence of numbers. This includes – numeric information– textual information and– Pictures, sound, video, etc.

Therefore, if we can derive a way to store and retrieve numbers electronically this method can be used by computers to store and retrieve any type of information.

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Computers Store ALL information using binary numbers

Computers use binary numbers in different ways to store different types of information.

Common types of information that are stored by computers are :

– Whole numbers (i.e. Integers). Examples: 8 97 -732 0 -5 etc.

– Numbers with decimal points. Examples: 3.5 -1.234 0.765 999.001 etc.

– Textual information (including letters, symbols and digits)

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Unsigned integers– Given n bits, it is possible to represent the

range of values from 0 to 2n - 1– For example an 8-bit representation would

allow representations that range 0 to 255

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Signed Magnitude– An extra bit in the most significant position is

designated as the sign bit which is to the left of an unsigned integer. The unsigned integer is the magnitude.

– A 0 in the sign bit means positive, and a 1 means negative

MMMMMMMMMMMMMMMS

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Signed Magnitude (cont.)– Given an n bit signed magnitude number the range

of values that it can represent is -(2n-1-1) to +(2n-1-1)

for example: 8 bits -127 to 12716 bits -32767 to 32767

– Signed magnitude representation associates a sign bit with a magnitude that represents zero, thus it has two distinct representation of zero:

00000000 and 10000000

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1’s Complement representation– For positive numbers, the representation is

the same as for unsigned integers where the most significant bit is always zero

– The additive inverse of a 1’s complement representation is found by inverting each bit.

– Inverting each bit is also called taking the 1’s complement

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1’s Complement representation Examples

0000 0011 (3)1111 1100 (-3)

0001 0111 (23)1110 1000 (-23)

0000 0000 (0)1111 1111 (0)

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2’s Complement representation– The additive inverse of a 2’s complement integer

can be obtained by adding 1 to its 1’s complement

– The 2’s complement representation for a negative number is the additive inverse of its positive representation

– An advantage of 2’s complement is that there is only one representation for zero

– Given an n bit 2’s complement number the range of values that it can represent is

-(2n-1) to +(2n-1-1)57

2’s Complement representation Examples010001 (17) 000000 (0)

101110 + 111111 +

1 1

101111 (-17) 1000000 (0)

take the 1’s complement

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6.0210 x 1023

radix (base)decimal point

mantissa exponent

Normalized form: no leadings 0s (exactly one digit to left of decimal point)

Alternatives to representing 1/1,000,000,000

–Normalized: 1.0 x 10-9

–Not normalized: 0.1 x 10-8,10.0 x 10-10

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1.02 x 2-1

radix (base)“binary point”

exponent

Computer arithmetic that supports it called floating point, because it represents numbers where the binary point is not fixed, as it is for integers

mantissa

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Normalized format: +1.xxxxxxxxxx2 x 2yyyy2

Multiple of Word Size (32 bits)

031S Exponent

30 23 22Mantissa

1 bit 8 bits 23 bits

S represents Sign Exponent represents y’s Mantissa represents x’s

To store letters and symbols, the computer assigns every character a numerical value.

Computers remember letters and other symbols by storing the binary number for the symbol.

For this system to work a standard numbering system needs to be defined and consistently used for all symbols that the computer needs to process.

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ASCII (American Standard Code for Information Interchange) is the standard numbering given to all characters.

“ASCII values” range in number from 1 to 128 (8 bits).

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Unicode is a computing industry standard for the consistent encoding, representation and handling of text expressed in most of the world's writing systems.

Unicode can be implemented by different character encodings. The most commonly used encodings are UTF-8 (which uses one byte for any ASCII characters, which have the same code values in both UTF-8 and ASCII encoding, and up to four bytes for other characters.

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A raster image, or bitmap, consists of a rectangular array of pixels.

Each pixel has a corresponding red, green, and blue value that combine to determine the color displayed by that pixel.

Audio analog to digital converters work by repeatedly measuring the amplitude of an incoming electrical pressure sound wave, and outputting these measurements as a long list of binary bytes.

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