《计算机英语》课件Chapter 6 System Software

1、? ?计算机英语计算机英语? ?课件课件Chapter 6 System Chapter 6 System SoftwareSoftwareChapter 6 System Software ObjectiveAfter reading this chapter, you should be able to:lDefine what the system software is.lDescribe the four categories of system software.lDiscuss the basic functions and categories of operating sys

2、tem.lDiscuss the advantages of utilities.lDefine device drivers.lDiscuss programming language and translators.6.2 Operating SystemslOperating systems, such as GNU, Microsoft Windows, Mac OS X or Linux, are prominent examples of system software. 6.2 Operating SystemsAccording to the modern understand

3、ing, an OS should be able to do the following:lProgram execution. lInterrupts. lProtected mode and supervisor mode.lMemory management .lVirtual memory. lMultitasking. lDisk access and file systems. lDevice drivers. lNetworking. lSecurity. lGraphical user interfaces. 6.2 Operating SystemsThe three ba

4、sic categories of operating systems: EmbeddedNetworkStand-alone6.2.1 Embedded Operating SystemslAn embedded operating system is a special-purpose computer system that is used for a particular task. lSome of the most common embedded systems used in everyday life are:RefrigeratorsMicrowave ovensTV, VC

5、R, DVD playersCamerasCars Personal digital assistantsPrinters Figure 6-3 A PDA has embedded operating system 6.2.2 Network Operating SystemlA network operating system (NOS) is software that controls a network and its message (e.g. packet) traffic and queues, controls access by multiple users to netw

6、ork resources such as files, and provides for certain administrative functions, including security.l A NOS is an OS that has been specifically written to implement and maintain networks. 6.2.2 Network Operating Systeml The examples of network operating systems are: 6WINDGate. 6WIND software packages

7、 that turn Linux distributions into routers control plane and data plane. Cisco IOS. Cisco IOS (formerly Cisco Internetwork Operating System) is a NOS having a focus on the internetworking capabilities of network devices. It is used on Cisco Systems routers and some network switches. BSD. BSD, also

8、used in many network servers. 6.2.3 Stand-alone Operating SystemslStand-alone operating systems also called desktop operating systems control a single desktop or notebook computer. lThese operating systems are located on the computers hard disk. 6.3 Utility softwarelUtility software also known as se

9、rvice programs perform specific tasks related to managing computer resources. lThe examples of utility softwares are: Disk storage utilities System profilers provide detailed information about the software installed and hardware attached to the computer. Anti-virus utilities scans for computer virus

10、es. Data compression utilities output a shorter stream or a smaller file when provided with a stream or file. Cryptographic utilities encrypt and decrypt streams and files. Registry cleaners clean and optimize the Windows registry by removing old registry keys that are no longer in use. Network mana

11、gers check the computers network, log events and check data transfer.6.4 Device DriverslA device driver is a computer program allowing higher-level computer programs to interact with a hardware device. 6.5 Programming Languages and TranslatorslProgramming languages are a vocabulary and set of gramma

12、tical rules for instructing a computer to perform specific tasks. lThe term programming language usually refers to high-level languages, such as BASIC, C+, C, COBOL, FORTRAN, Ada, and Pascal. 6.5 Programming Languages and TranslatorslTraditionally, computer programming languages are divided into fiv

13、e generations. Figure 6-5 Five generations of programming languages Machine language Assembling language High-level programming 4GL Language used for AI and neural networks 6.5.1 CompilerlA compiler is a special program that takes written source code and turns it into machine language. lWhen a compi

14、ler executes, it analyzes all of the language statements in the source code and builds the machine language object code. After a program is compiled, it is then a form that the processor can execute one instruction at a time.6.5.1 CompilerlIn some operating systems, an additional step called linking

15、 is required after compilation. Linking resolves the relative location of instructions and data when more than one object module needs to be run at the same time and both modules cross-reference each others instruction sequences or data.6.5.2 AssemblerlAn assembler translates assembly language into machine language. It uses computer-specific commands and structure similar to machine language, but assembly language uses names instead of numbers.6.5.3 InterpreterlIt converts programs into machine-executable f