Computer Systems Reading Sequence: • 1.1 Computer Basics • 1.2 Evolution of Computer Systems • 1.3 Data Representation in a Computer System Assessments: • Exercise 1
Computer Systems 1.1 Computer Basics • Learning Goal: To gain a general overview of computer system components, the hardware system, the software system, and the network system.
Computer Systems 1.1.1 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.
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.
Computer Systems • Hardware 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.
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
Figure 4Interaction among hardware system, operating system software, application software, and users
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
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
Computer Systems • Network SystemThe 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.
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.
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 5.
Computer Systems 1.2 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.
1.2.1 Brief History • 1200s—Manual Calculating DevicesThe first calculation device, the abacus, was used in China. It involved manually moving beads to do calculations.
1600s—Mechanical CalculatorsMechanical 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.
1800s—Punched Cards • Punched cards use holes following a specific pattern to represent 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.
1940s—Vacuum Tubes • 1945: The first computer prototype using vacuum 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
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.
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。
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.
1960s—Integrated Circuits (集成电路) • An integrated circuit, also called a “microchip” 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).
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.
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。
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。
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。
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。
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。
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.
Moore’s Law • 1965年4月Intel公司的创建者之一，Gordon 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“。
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。
Table 1Number of transistors used in Intel processors over the years (From Intel Site)
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).
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.
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.
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.
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.
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.