2 Systems Architecture, Fifth Edition Chapter Goals 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 Define the role and function of application and system software

3 Systems Architecture, Fifth Edition Chapter Goals (continued) Describe the economic role of system and application development software Describe the components and functions of computer networks

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

5 Systems Architecture, Fifth Edition Automated Computation Mechanical –Early computers with limited capabilities Electronic –Fast, accurate reliable Optical –Fast, accurate reliable

6 Systems Architecture, Fifth Edition 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

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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, more reliable, easier to build than mechanical counterparts

9 Systems Architecture, Fifth Edition 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

10 Systems Architecture, Fifth Edition Computer Capabilities Processing Storage Communication

11 Systems Architecture, Fifth Edition Processor Device that performs data manipulation and transformation functions –Computation –Comparison –Data movement among memory, mass storage, and input/output devices

12 Systems Architecture, Fifth Edition Processor Terminology Instructions Programs General-purpose and special-purpose processors Formulas and algorithms Comparisons and branching

13 Systems Architecture, Fifth Edition Storage Capacity Types of information to be stored –Intermediate processing results –Data –Programs Characteristics of storage devices vary widely –Cost –Access speed –Reliability

14 Systems Architecture, Fifth Edition Input/Output Capability Must encompass many communication modes –Sound, text, and graphics (for humans) –Electronic or optical communication (for other computers)

15 Systems Architecture, Fifth Edition Computer Hardware

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17 Systems Architecture, Fifth Edition Central Processing Unit General-purpose processor –Executes all instructions (computation and comparison functions) –Directs all data movement

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19 Systems Architecture, Fifth Edition CPU Components Arithmetic logic unit (ALU) Contains electrical circuits that implement each instruction RegistersInternal storage locations that can each hold a single instruction or data item Control unitControls movement of data to and from CPU Accesses program instructions and issues appropriate commands to ALU

20 Systems Architecture, Fifth Edition System Bus Internal communication channel that connects all other hardware devices Primary pathway for moving data and instructions among hardware components Capacity is critical to performance, secondary storage, and I/O device performance

21 Systems Architecture, Fifth Edition Primary Storage (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 Systems Architecture, Fifth Edition 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

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24 Systems Architecture, Fifth Edition Input/Output Devices Implement external communication functions Human-oriented communication devices (e.g., keyboard, mouse, printer) Computer-oriented communication devices (e.g., modem, network interface unit)

25 Systems Architecture, Fifth Edition Computer System Classes MicrocomputerMeets information processing needs of single user Examples: PCs, network computers Midrange computerSupports many programs and users simultaneously MainframeHandles information processing needs of large number of users and applications Designed for large amounts of data storage and access SupercomputerDesigned for rapid mathematical computation

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27 Systems Architecture, Fifth Edition Multicomputer Configurations Any organization of multiple computers to support a specific set of services or applications Common configurations –Cluster –Blade –Grid

28 Systems Architecture, Fifth Edition 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 Systems Architecture, Fifth Edition Blade Circuit board that contains most of a server computer; a specialized cluster Same advantages and disadvantages as a cluster, but also: –Concentrate more computing power in less space –Are simpler to modify

30 Systems Architecture, Fifth Edition 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 Systems Architecture, Fifth Edition 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 –Large computer databases –Widespread adoption of graphical user interfaces –Multicomputer configurations

32 Systems Architecture, Fifth Edition The Role of Software Translates user requests into machine instructions Performs complex translation process that bridges two gaps –Human language to machine language (binary) –High-level abstraction to low-level detail

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34 Systems Architecture, Fifth Edition Software Types Application program Stored set of instructions for responding to a specific information-processing tasks Used directly by end users Utility program Contains instructions for performing general-purpose tasks Usually operates invisibly in the background System software Implements utility functions needed by many application programs Allocates computer resources to application programs Manages computer resources Does not interact with end users

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36 Systems Architecture, Fifth Edition System Software Layers System management System services Resource allocation Hardware interface

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38 Systems Architecture, Fifth Edition Operating Systems Most important system software component Collection of utility programs that provides: –Administrative utilities –Utility services to application programs –Resource allocation functions –Direct control over hardware

39 Systems Architecture, Fifth Edition Operating System Functions Program storage, loading, and execution File manipulation and access Secondary storage management Network and interactive user interfaces

40 Systems Architecture, Fifth Edition Application Development Software Programs used to develop other programs Types –Program translators –Program editors –Debugging tools –System development tools

41 Systems Architecture, Fifth Edition Economics of System and Application Development Software System software consumes hardware resources Cost per unit of computing power has rapidly decreased Software is more cost-effective when reused many times

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43 Systems Architecture, Fifth Edition Computer Networks Set 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

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45 Systems Architecture, Fifth Edition External Resources Ability to share data, programs, and hardware resources among computers Gives modern organizations flexibility to deploy and redeploy computing and information resources to satisfy rapidly changing needs

46 Systems Architecture, Fifth Edition 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

47 Systems Architecture, Fifth Edition 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

48 Systems Architecture, Fifth Edition Summary Basic elements of computer system architecture –Hardware –Software –Networks Importance of knowing how all components of a computer system interrelate as well as their internal workings