Chapter 1

Introduction to Computer Systems

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Computer SystemsReading Sequence: • 1.1 Computer Basics • 1.2 Evolution of Computer Systems• 1.3 Data Representation in a Computer

System

Assessments: • Exercise 1

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Computer Systems

1.1 Computer Basics

• Learning Goal: To gain a general overview of computer system components, the hardware systemthe hardware system, , the software the software systemsystem, and the network systemthe network system.

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Computer Systems1.1.1 Components of a Computer System • Hardware system• Software system—Operating System

Software and Application Software• Network System• A computer is an electronic machine that

performs input, processing, storing, and output according to programmed instructions to carry out specific tasks.

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Computer Systems• The modern computer operates in a similar

fashion. Input to a computer can be sent through the keyboard or mouse. The computer then processes the input, stores the result, and displays the result via the monitor, speaker, printer, or other output devices.

• In general, a computer system can be decomposed into the hardware system, the software system, and the network system. Each of these subsystems will be discussed in more detail in subsequent units of this course. See the figure below.

6Figure 1 Components of a computer system

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Computer SystemsHardware System The hardware system consists of external

and internal physical components that enable a computer to accept input, process the input, store data, and produce outputs.

More details will be discussed in Chapter 2. The figures below show some external

hardware components of a computer.

8Figure 2 Hardware components

9Figure 3 Components inside the system unit

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Computer Systems Software System ---- Operating System

Software and Application Software The operating system software serves

as the interface between application software and the hardware components

The application software interfaces with the users of the computer system

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Figure 4 Interaction among hardware system, operating system software, application software, and users

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• Operating system software provides instructions to hardware system components. Such as Microsoft Windows, Unix, etc. When an input is entered, the operating system program provides instructions to send the input to appropriate hardware components (CPU) for processing. Then, it provides instructions for the result to be sent to the appropriate output device (CRT). －－ Chapter 3

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• Application software provides instructions that enable the user to perform specific tasks such as creating presentations, composing written documents, and editing images. Examples of application software programs is Microsoft Word.

• Application software instructions are handled by the operating system. For instance, when you open a file using Microsoft Word, first the application provides the user-interface for you to specify which file you want to open (for example, the menu bar). Once you have selected the file, the application notifies the operating system that a certain file is needed. The operating system then requests for the file from the hard drive of the computer. －－ Chapter 4

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Computer SystemsNetwork System

The network system manages how data is transferred from one computer to another and how different components of a network system work together. The diagram below illustrates the network components needed for a computer to communicate to other computer via the Internet.

15Figure 5 Network connection components

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• A network interface card (NIC) sends data from a computer over a network, and collects incoming data sent by other computers

• A modem is a device that enables data from a computer to be transmitted via phone lines or television cable lines to reach other computers on the Internet.

• A computer also needs an Internet service provider such as China Telecom to enable its connection to the Internet.

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• Application software such as Web browsers (for example, Internet Explorer and Netscape) and electronic mail (for example, Outlook and Netscape Mail) also enhance the usefulness of a network system. More about how the network system works will be discussed in

Chapter 55..

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Computer Systems1.2 Evolution of Computer Systems • You will learn about both the origins and the advancements

of computer technology. • You will explore innovative uses of computers to enhance

different aspects of our lives. You may also discover how computers can be helpful in your field of interest, whether it is education services, medical research, business management, or entertainment.

• You can read about the computer industry, which has become a major segment of the world economy, generating many types of career opportunities and businesses.

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1.2.1 Brief History • 1200s—Manual Calculating Devices

The first calculation device, the abacus, was used in China. It involved manually moving beads to do calculations.

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• 1600s—Mechanical Calculators Mechanical calculators used wheels, gears, and counters.

1642: Blaise Pascal invented the Pascaline, which is a mechanical calculator. The machine used some principles of the abacus, but used wheels to move counters.

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• 1800s—Punched Cards Punched cards use holes following a specific pattern to r

epresent the instructions given to the machine or stored data.

1834: Charles Babbage designed a new general-purpose calculating device, the Analytical Engine, which is the ancestor of modern computers. It included the essential components of present-day computers, which are input, process, storage, and output of data.

Babbage's assistant, Augusta Ada King, would create the instruction routines stored on punched cards to tell the machine what to do. Instruction routines used by the computer are known as "computer programs." She is thus the first female computer programmer, and in her honor, the U.S. Defense Department named the programming language ADA.

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• 1940s—Vacuum Tubes1945: The first computer prototype using v

acuum tubes, ENIAC (Electronic Numerical Integrator and Computer) was designed to calculate trajectory tables for the U.S. Army during World War II, but it was not completed until three months after the war.

The first commercially successful computer, UNIVAC was developed by Eckert-Mauchly Computer Corporation

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ENIAC - The first electronic computer

• 1945: The first computer prototype using vacuum tubes, ENIAC (Electronic Numerical Integrator and Computer) was designed to calculate trajectory 弹道 tables for the U.S. Army during World War II, but it was not completed until three months after the war.

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ENIAC - The first electronic computer

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ENIAC - The first electronic computer

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ENIAC - The first electronic computer

• ENIAC: 17468 vacuum tubes, 7200 diodes( 二极管 ) ， 70000 resistors( 电阻 ) ， 10000 capacitors( 电容器 ),6000 relays( 继电器 ) ，500000 jointing points( 焊点 )

• 机器被安装在一排 2.75 米高的金属柜里，占地面积为 170 平方米左右，总重量达 到 30吨，其运算速度达到每秒钟 5000 次加法。

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• 1950s—Transistors （晶体管）Transistors performed functions similar to

vacuum tubes but they were smaller, cheaper, and more reliable. Additionally, they consumed less power. The ability for transistors to replace vacuum tubes was first demonstrated in AT&T’s Bell Laboratories. Transistor-based computers could perform 200,000 to 250,000 calculations per second.

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Transistors （晶体管）

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• 1960s—Integrated Circuits ( 集成电路 )An integrated circuit, also called a “microc

hip” or “chip,” is a thin slice of silicon( 硅 ) packed with microscopic circuit elements such as wires, transistors, capacitors( 电容 ), and resistors( 电阻 ).

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• 1970s to Present—Microprocessor The microprocessor combined components

of a computer on a microchip. Before the microprocessor was developed, each integrated circuit had to be manufactured for a particular purpose, but now a microprocessor can be manufactured and then programmed for various purposes to other needs.

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1970s to Present—Microprocessor

• The first general-purpose microprocessor, Intel 4004, was developed in 1971 by Ted Hoff.

• 该处理器在面积约 12 平方毫米的芯片上集成了2250 个晶体管，运算能力足以超过 ENIAC 。

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Microprocessor• 1982 年 2 月， Intel

发布 80286 处理器。时钟频率提高到 20MHz ，并增加了保护模式，可访问 16M 内存。支持 1GB 以上的虚拟内存。每秒执行 270 万条指令，集成了 134000 个晶体管。

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Microprocessor

• 1985 年 7 月， Intel 公司推出了计算机历史上有着举足轻重地位的 80386 处理器，这也是 Intel 公司的第一枚 32 位处理器。

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Microprocessor

• 1989 年 4 月 10 日， Intel 公司在拉斯维加斯电脑大展上首度发表集成有 120 万晶体管的 486 处理器。

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Microprocessor• 1993 年 3 月 22 日，

Intel 公司正式发布奔腾（ pentium ）处理器。初期发布的奔腾集成了 300多万个晶体管，工作在 60-66MHz ，每秒钟可执行 1 亿条指令。

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Microprocessor chip

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• Pace of Advancement As transistors become smaller, more transistors

can be placed on a given chip. In 1965, Gordon Moore, a founder of Intel, one of

the largest microchip manufacturers, predicted that the number of transistors that can be put on a microchip will double every 12 months, until physical limitations are reached. This observation was termed "Moore’s Law." Now the exponential growth has slowed down to doubling every 18 months, nevertheless, the rate of growth is still exponential.

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Moore’s Law• 1965 年 4 月 Intel 公司的创建者之一， Gor

don Moore 在《电子》杂志上发表了一篇很好地预测了未来集成电路发展趋势的文章，它就是后来人们常说的摩尔定律的原身。

• 摩尔在《电子》杂志上发表的那篇文章中有这么一句话：”硅晶元每平方英寸所能容纳的晶体管数量每 12 个月将增加一倍“。这就是摩尔定律最为人熟知的表达形式，也称为“晶体管密度倍增定律“。

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Moore’s Law

• IC 上可容纳的晶体管数目，约每隔 18 个月便会增加一倍，性能也将提升一倍。

• 摩尔定律是指一个尺寸相同的晶片上，所容纳的晶体管数量，因制造技术的提升，每 18 个月会加倍，但售价相同；芯片的容量是以 Transistor 的数量多少来计算，晶体管愈多则芯片执行运算的速度越快，当然，所需要的生产技术越高明。

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  Year of Introduction Transistors

4004 1971 2,250

8008 1972 2,500

8080 1974 5,000

8086 1978 29,000

286 1982 120,000

386TM processor 1985 275,000

486TM DX processor 1989 1,180,000

Pentium® processor 1993 3,100,000

Pentium II processor 1997 7,500,000

Pentium III processor 1999 24,000,000

Pentium 4 processor 2000 42,000,000

Table 1 Number of transistors used in Intel processors over the years (From Intel Site)

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1.2.2 Applications of Computer Systems In Education Multimedia-Facilitated Learning ( 多媒体教与学 )

Multimedia -- the use of computers to present text, graphics, video, animation, and sound in an integrated way

Simulation-Based Education （计算机仿真）Computers can be programmed to generate images and animations that model other systems. These systems can be those that exist in the physical world in which we live (for example, people and objects), as well as those from the imagination (e.g. life on the moon and mythical beings).

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Medical Training A 3-D virtual reality (VR) software enables students to practice trauma assessment and treatment on wounded man using their computer. This would eliminate the need to send trainees to the field and expedite the training process.

Molecule Modeling Researchers could use a software visualization tool to create 3-D models of chemical molecules and explore their properties.

45DNA modeling

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Military Training ( 军事训练 )3-D simulations can be used build virtual environments that replicate the interior of military crafts to train engineering officers for material readiness assessment. Using simulations, physical crafts do not need to be used during training, and the number of people that can be trained at one time is not limited. Additionally, training can be provided to persons in different geographic locations.

47Virtual training for military personnel

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Intelligent Machine-Based Training Computer systems can be programmed to react based on user behavior. For example, to facilitate learning a foreign language.

Interactive Learning A computer project involves using Music Toys to engage children in listening, performing, and music-composing tasks. Children can play along with some of the world's most accomplished musicians who are participating in this project.

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1.2.2 Applications of Computer Systems

In Business Supply Chain Management

Supply chain management aims to manage and track the supply of raw components, their usage in the manufacturing process, and delivery of finished products to customers. Some supply chain management software applications use mathematical algorithms to improve the flow of the supply chain and minimize inventory.

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Project Management Product development information, which includes product requirements, work schedules, project milestones, budgets, and product design need to be organized and tracked to monitor the progress of the project. Software applications are capable of keeping track of the product database, work schedule, and budget of the project to help you pinpoint potential barriers to the timely completion of the project.

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Customer Relationship ManagementCustomer relationship management (CRM) is a process that gathers information about the customer base, marketing effectiveness, and market trends in order to learn more about customers' behaviors. A CRM software system can collect information about customer demographics, and investigate customer-purchasing behaviors with the objective of predicting customer needs and increasing revenues.

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Sales and Marketing Using Electronic CommerceUsing the Internet, commerce can be conducted online through the World Wide Web.

Manufacturing Research Computer simulation tools can be used to design products.

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1.2.2 Applications of Computer Systems

In Entertainment Movies Video Games Music Digital Photography Travel Wearable Computer Systems

Computer systems can also be embedded in devices that are more portable such as a wristwatch or a headphone.

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Computer Systems1.3 Data Representation in a Computer System

(SECTION A Chapter 2 in Textbook)• 1.3.1 Bits and Bytes. Learning Goal: Knowledge

of how data is represented using binary digits of 0's and 1's. Also, learn about how data storage capacity is described using typical units of measure used over the years.

• 1.3.2 Number Systems. Learning Goal: Knowledge of numbering systems used to represent data in computing.

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1.3.1 Bits and Bytes Data Representation Using Binary Digits

A piece of data, such as an alphabet letter, may be represented using a sequence of binary digits- 0's and 1's. There are several types of codes used to represent character data. For example, using extended ASCII (America Standard Code for Information Interchange) code, the alphabet letter "a" can be represented using a series of eight binary digits, "01100001." Each binary digit is called a bit. And, eight bits is one byte. Extended ASCII code uses eight bits (or one byte) to represent input characters.

56ASCII Code

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Increasing Need for BytesAt first small amounts of memory such as thousands of bytes were all that was needed to handle the simple spreadsheet and word processing tasks. But, before long, users wanted software to allow them to do more tasks such as creating drawings and generating complex page layouts. As consumer demand grew, computing requirements also grew. This demand led to new developments that expanded memory capacities.

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the storage capacity over the years since the 1970s

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Computer Systems

1.3.2 Number SystemsDecimal

Place 4th 3rd 2nd 1st 0th

Digit 4 3 8 7 2

Exponential value of the place 104 103 102 101 100

Decimal value of the place10,000

1,000

100 10 1

Table 1 Exponential and decimal values corresponding to a digit's place in a number

4 × 104 + 3 × 103 + 8 × 102 + 7 × 101 + 2 × 100 =4 × 10,000 + 3 × 1000 + 8 × 100 + 7 × 10 + 2 × 1 =40,000 + 3000 + 800 + 70 + 2 =43,872

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Place 3 2 1 0

Exponential value of the place 43 42 41 40

Decimal value of the place 64 16 4 1

Calculation 89 ÷ 64 25 ÷ 16 9 ÷ 4 1 ÷ 1

Result 1 1 2 1

Remainder 25 9 1 0

Table 2 Converting numbers from base 10 to base 4Therefore, 8910 = 11214.

Binary

101101102

1 × 27 + 0 × 26 + 1 × 25 + 1 × 24 + 0 × 23 + 1 × 22 + 1 × 21 + 0 × 20 =1 × 128 + 0 × 64 + 1 × 32 + 1 × 16 + 0 × 8 + 1 × 4 + 1 × 2 + 0 × 1 =128 + 0 + 32 + 16 + 0 + 4 + 2 + 0 = 182

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Hexadecimal Decimal Binary Hexadecimal

0 0000 0x0

1 0001 0x1

2 0010 0x2

3 0011 0x3

4 0100 0x4

5 0101 0x5

6 0110 0x6

7 0111 0x7

8 1000 0x8

9 1001 0x9

10 1010 0xA

11 1011 0xB

12 1100 0xC

13 1101 0xD

14 1110 0xE

15 1111 0xF

0x3B=001110112=32 + 16 + 8 + 2 + 1 =

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TECHTALK: The Boot Process • The typical computer system boots over a

nd over again with no problems, starting the computer's operating system (OS) and identifying its hardware and software components that all work together to provide the user with the complete computing experience. But what happens between the time that the user powers up the computer and when the GUI icons appear on the desktop?

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• In order for a computer to successfully boot, its BIOS, operating system and hardware components must all be working properly; failure of any one of these three elements will likely result in a failed boot sequence.

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• When the computer's power is first turned on, the CPU initializes itself, which is triggered by a series of clock ticks generated by the system clock. Part of the CPU's initialization is to look to the system's ROM BIOS for its first instruction in the startup program. The ROM BIOS stores the first instruction, which is the instruction to run the power-on self test (POST), in a predetermined memory address. POST begins by checking the BIOS chip and then tests CMOS RAM. If the POST does not detect a battery failure, it then continues to initialize the CPU, checking the inventoried hardware devices (such as the video card), secondary storage devices, such as hard drives and floppy drives, ports and other hardware devices, such as the keyboard and mouse, to ensure they are functioning properly.

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• Once the POST has determined that all components are functioning properly and the CPU has successfully initialized, the BIOS looks for an OS to load.

• The BIOS typically looks to the CMOS chip to tell it where to find the OS, and in most PCs, the OS loads from the C drive on the hard drive even though the BIOS has the capability to load the OS from a floppy disk, CD or ZIP drive. The order of drives that the CMOS looks to in order to locate the OS is called the boot sequence, which can be changed by altering the CMOS setup. Looking to the appropriate boot drive, the BIOS will first encounter the boot record, which tells it where to find the beginning of the OS and the subsequent program file that will initialize the OS.

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• Once the OS initializes, the BIOS copies its files into memory and the OS basically takes over control of the boot process. Now in control, the OS performs another inventory of the system's memory and memory availability (which the BIOS already checked) and loads the device drivers that it needs to control the peripheral devices, such as a printer, scanner, optical drive, mouse and keyboard. This is the final stage in the boot process, after which the user can access the system 抯 applications to perform tasks.

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Boot Process Steps

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Exercise 1 & Solution • Prerequisite: None• Direction: • Use a word processor (Microsoft Word) to

answer the questions in the exercise. • Your grade will be based upon the following:

Questions• Question 1. Applications of Computer

Systems (30%)• Question 2. Number Conversions (40%)• Question 3. Data Representations in a

Computer System (30%)

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Question 1• Question 1. Applications of Computer Systems• A.Your friend Jen is a native French speaker who has i

mmigrated to the United States to teach French in high school. She pays special attention to her students’ pronunciation and works very hard to show her students how to pronounce words correctly in French. Knowing that you are taking a course in computer systems, she asks if you know of any computer technology that can help her students learn to speak a foreign language with correct pronunciations. What would be your response to her?

• Answer varies, but should describe the use of software tools such as Fluency: Foreign Language Pronunciation Training Software, which interprets pronunciations and provides feedback to users. (10)

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Question 1• B. Your uncle has worked for 30 years as a sales

representative. He has accumulated over 10,000 business cards throughout his career. He keeps a stack of notebooks where he writes down each customer’s contact information, profile, and special interests. When making customer contacts, he spends a large amount of time trying to identify the target group of customers. Describe an easier and faster way of organizing the information he has collected making use of available technology.

• Answer varies, but should describe the use of existing products such as Microsoft Outlook, PDA devices, etc. (10)

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Question 1• C. Your friend Alex is tasked to generate a

number of series of posters of the same picture varying in poster size, color tone, and layout for a class project due in 5 hours. He is very frustrated because each poster design would take him about 3 hours to produce with color pencils. How could software be used to solve this problem?

• Answer varies, but should describe the use of graphic software programs such as Adobe Photoshop. (10)

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• Question 2. Number Conversions

• In this section, you will convert numbers among binary, decimal and hexadecimal representations.

• a. Complete the following chart by converting the numbers given in one of the notations to the other two. Show calculations.

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Binary Decimal Hexadecimal

101 0101

110 0110

15

250

0xAF

0x1B6

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calculations• 1st row:• 1+4+16+64 = 85• 101=5 0101=5 Hex: 0x55• 2nd row:• 2+4+32+64 = 102• 110=6 0110=6 Hex: 0x66• 3rd row:• 15 mod 2=1, 7 mod 2=1, 3 mod 2=1, 1 mod 2=1

Binary: 1111• 1111=15=F Hex: 0xF

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calculations• 4th row:• 250 mod 2=0, 125 mod 2=1, 62 mod 2=0, 31 mod 2=1,

15 mod 2=1, 7 mod 2=1, 3 mod 2=1, 1 mod 2 = 1 Binary: 1111 1010

• 1111=15=F 1010=10=A Hex: 0xFA• 5th row:• A=10=1010 F=15=1111 Binary: 1 0101 111• 1+2+4+8+32+128=175• 6th row:• 1 = 0001 B=11=1011 6=0110 Binary: 1 1011 0110• 2+4+16+32+128+256=438• (12)

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Binary Decimal Hexadecimal

101 0101 85 0x55

110 0110 102 0x66

1111 15 0xF

1111 1010 250 0xFA

1010 1111 175 0xAF

1101 10110 438 0x1B6

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• What is the minimum number of bits that can be used to represent the decimal number 213? (Hint: convert 213 to binary.)8 bits (7)

• What is the minimum number of bytes that can be used to represent the decimal number 213?1 byte (7)

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• What is a purpose of using hexadecimal notation?

Hexadecimal notation is used as shorthand for binary to express binary values more concisely. (7)

What is ASCII code?

ASCII code is the American Standard Code for Information Interchange. It is a code that represents characters as a series of 1s and 0s. (7)

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• Question 3. Data Representations in a Computer System

• Computer systems are made up of electrical components that are either on, or off, representing 1’s and 0’s, also called binary numbers. All data, such as numbers, are converted into binary representations in the computer system. The Extended ASCII chart below shows characters and their binary representations. Use the chart below and a calculator to answer the following questions:

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• You can obtain the binary representation of a word by concatenating the ASCII values of each letter. For example, “SSD2” in binary representation is 01010011 01010011 01000100 00110010.

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• “Fun” in binary representation is _____.01000110 01110101 01101110 (6)

• “Play” in binary representation is _____, which is equivalent to _____ in decimal representation. 01010000 01101100 01100001 01111001, 1349280121 (6)

• 01100011 01100001 01110010 01100101 01100101 01110010 01110011 is the binary representation of the ASCII string _____.careers (6)

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• 0x39BA317274 is a hexadecimal representation of the ASCII string _____.

start (6)

• 1751478885 is the decimal representation of the ASCII string _____.

here (6)