Systems Architecture, Sixth Edition. Chapter 2 Introduction To Systems Architecture

Transcription

1 Systems Architecture, Sixth Edition Chapter 2 Introduction To Systems Architecture

2 Chapter Objectives In this chapter, you will learn to: Discuss the development of automated computing Describe the general capabilities of a computer Describe computer system components and their functions List computer system classes and their distinguishing characteristics 2

3 Chapter Objectives (continued) Define the roles, functions, and economics of application and system software Describe the components and functions of computer networks 3

4 Systems Architecture Describes structure, interaction, and technology of computer system components Capabilities of a computer Accept numeric inputs Perform computational functions Communicate results 4

5 Automated Computation Mechanical Early computers with limited capabilities Performed repetitive mathematical calculations Electronic Electrons used rather than gears and wheels Fast, accurate reliable Optical Light is the basis for computation Fast, accurate reliable 5

6 Mechanical Implementation Mechanical representation of a mathematical calculation Difference engine: Charles Babbage, 1821 Limitations and shortcomings Complex design and construction Wear, breakdown, and maintenance of parts Limits on operating speed 6

7 Figure 2.1 Charles Babbage s Difference Engine Courtesy of Science Museum/Science & Society Picture Library 7

8 Electronic Implementation Stores numerical values as magnetic charges or by positioning electrical switches Can convert physical movement into electrical signals, or vice versa World War II: impetus for change Faster and more reliable for complex calculations Easier to build than mechanical counterparts 8

9 Optical Implementation Harnesses energy of a moving photon Represents data as pulses of light stored directly or indirectly by materials that reflect or don t reflect light Now common in computer networks that cover large distances 9

10 Quantum Computing Quantum physics describes the behavior of matter at a subatomic level Rules differ from classical physics Qubit: any matter that stores data in multiple simultaneous quantum states More efficient than conventional computers 10

11 Computer Capabilities General-purpose processor Storage capacity Flexible communication 11

12 Processor Device that performs data manipulation and transformation functions Computation Comparison Data movement among memory, mass storage, and input/output devices 12

13 Processor (continued) Instructions Programs General-purpose and special-purpose processors Formulas and algorithms Comparisons and branching Conditions Logic instructions 13

14 Storage Capacity Types of information to be stored Intermediate processing results Data Programs Characteristics of storage devices vary widely Cost Access speed Reliability 14

15 Input/Output Capability Must encompass many communication modes Sound, text, and graphics (for humans) Electronic or optical communication (for other computers) 15

16 Computer Hardware Figure 2.6 The major functions of computer hardware Courtesy of Course Technology/Cengage Learning 16

17 Hardware Components Figure 2.7 The hardware components of a computer system Courtesy of Course Technology/Cengage Learning 17

18 Central Processing Unit General-purpose processor Executes all instructions (computation and comparison functions) Directs all data movement 18

19 Components of the CPU Figure 2.8 Components of the CPU Courtesy of Course Technology/Cengage Learning 19

20 CPU Components Arithmetic logic unit (ALU) Registers Control unit Contains electrical circuits that implement each instruction Internal storage locations that can each hold a single instruction or data item Controls movement of data to and from CPU Accesses program instructions and issues appropriate commands to ALU 20

21 System Bus Internal communication channel that connects all other hardware devices Main channel for moving data and instructions among hardware components Capacity is critical to performance, secondary storage, and I/O device performance 21

22 Primary Storage Also known as main memory Holds program instructions and data for currently executing programs Implemented with random access memory (RAM) Provides access speed and allows CPU to read or write to specific memory locations Volatile; does not provide permanent storage 22

23 Secondary Storage Composed of high-capacity nonvolatile storage devices that hold: Programs not currently being executed Data not needed by currently executing programs Data needed by currently executing programs that does not fit within available primary storage 23

24 Table 2.1 Comparison of storage types 24

25 Input/Output Devices Implement external communication functions Human-oriented communication devices (e.g., keyboard, pointing devices, voicerecognition devices) Computer-oriented communication devices (e.g., modem, network interface unit) 25

26 Computer System Classes Microcomputer Portable Midrange computer Mainframe Supercomputer Meets information processing needs of single user Examples: PCs, network computers Meets information processing needs of a single user at a variety of levels Examples: laptop, network, PDA Supports many programs and users simultaneously Handles information processing needs of large number of users and applications Large amounts of data storage and access Designed for rapid mathematical computation 26

27 Table 2.2 Representative products in various computer classes (2009) 27

28 Multicomputer Configurations Any organization of multiple computers to support a specific set of services or applications Common configurations Cluster Blade Grid Could 28

29 Cluster Group of similar or identical computers that cooperate to provide services or execute a common application Connected by high-speed network Typically located close to one another Advantages: scalability and fault tolerance Disadvantages: complex configuration and administration 29

30 Blade Circuit board that contains most of a server Same advantages and disadvantages as a cluster, but also: Concentrate more computing power in less space Are simpler to modify 30

31 Grid Group of dissimilar computer systems, connected by high-speed network, that cooperate to provide services or execute a common application Computers may be in separate rooms, buildings, or continents Computers work cooperatively at some times, independently at others 31

32 Cloud Set of computing resources with two components: Front-end interfaces Back-end resources Specific way of organizing computing resources for maximum availability and accessibility Minimum complexity in the user or service interface 32

33 Bigger Isn t Always Better Grosch s Law (1952) has been rewritten due to: Multiple classes of computers Expanded abilities to configure computers for specific purposes Increased software costs relative to hardware costs Multicomputer configurations 33

34 The Role of Software Translates user needs and requests into CPU instructions Performs complex translation process that bridges two gaps Human language to machine language (binary) High-level abstraction to low-level detail 34

35 Figure 2.12 The role of software as a translator between user requests and CPU instructions 35

36 Software Types Application program Utility program System software Stored set of instructions for responding to a specific request Used directly by end users Contains instructions for performing generalpurpose tasks Usually operates invisibly in the background Performs utility functions needed by many application programs Allocates computer resources to application programs. Manages computer resources Does not interact with end users 36

37 Figure 2.13 The interaction between the user, application software, system software, and computer hardware Courtesy of Course Technology/Cengage Learning 37

38 System Software Layers System management System services Resource allocation Hardware interface 38

39 Figure 2.14 Software layers and their relationship to hardware Courtesy of Course Technology/Cengage Learning 39

40 Operating Systems Most important and prevalent system software component Collection of utility programs that provides: Support for users and application programs Allocation of resources to multiple users and application programs Controlling access to hardware 40

41 Operating System Functions Program storage, loading, and execution File manipulation and access Secondary storage management Network and interactive user interfaces 41

42 Application Development Software Programs used to develop other programs Types Program translators Program editors Debugging tools System development tools 42

43 Economics of System and Application Development Software System software consumes hardware resources Cost per unit of computing power has decreased rapidly Software is more cost effective when reused many times 43

44 Figure 2.15 The change over time in related costs of hardware, application software, and system software in a typical information system Courtesy of Course Technology/Cengage Learning 44

45 Computer Networks Consist of hardware and software components that enable multiple users and computer systems to share information, software, and hardware resources Enables many types of personal communication 45

46 Figure 2.17 Computer network functions and their relationship to computer hardware and software Courtesy of Course Technology/Cengage Learning 46

47 External Resources Data available in many forms, including: Text files Sound and video Databases Web pages One computer can ask another to run a program and transmit results or receive a file containing a program and run it locally Can also share hardware devices of all types 47

48 Network Software Finds requested resources on the network Negotiates resource access with distant resource allocation software Receives and delivers resources to requesting user or program May also listen for and validate resource requests and deliver resources via the network 48

49 Network Communication and the Physical Network Network communication devices Simpler than I/O devices; do not need to convert data represented electronically into another form Must support communication at high speeds Physical network Complex combination of communication protocols, methods of data transmission, and network hardware devices 49

50 Summary Basic elements of computer system architecture Hardware Software Networks Computer system consist of a CPU, primary storage, secondary storage, and I/O devices Software translates user requests into machine instructions Operating system is most important system software component 50