System Programming and administration CS 308 Amal Aalblowie@su.edu.sa

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Course Information

Topics will covered (ان شاء الله) Background System Software and Machine architecture Software tools Overview of Compilers Introduction to Assemblers Loaders and its types Linux Operating System Linux commands Linux Job & Process Management Linux System Administration

System Programming and administration Lecture 1 Background and Evolution of system programming

1.1 Introduction Computer Systems Consist of Software consists of Hardware Software Data User Software consists of System Software Application Software

1.1 Introduction What is System? What is Programming? System is the collection of various components ( e.g. College is a system). What is Programming? Art of designing and implementing the programs.

1.1 Introduction What is Software ? Two types of software Software is collection of many programs Two types of software System software These programs assist general use of application programs. Application software These are the software developed for the specific goal

1.1 Introduction System Software includes Operating systems Command line interface UNIX、DOS Graphical User interface MacOS 、Windows

1.1 Introduction System Software includes Language Translators Assembler Compiler Interpreter Macro Processor:Macro is a single line abbreviation for group of instructions.

1.1 Introduction Language Translation Flow Compile Linker Program Coding Compile Problem Definition Library Linker Object File *.OBJ Execution file *.exe

1.1 Introduction Service Programs Loader and Linker Text Editor Debugger Data Base Management Systems (DBMS)

1.1 Introduction System Program These are programs which are required for the effective execution of general user programs on computer system System Programming It is an art of designing and implementing system programs.

1.1 Introduction What is system programming…? System programming is the activity of programming system software. Systems programming aims to produce software which provides services to the computer hardware . It requires a greater degree of hardware awareness.

1.2 Need Of System Software The basic need of system software is to achieve the following goals To achieve efficient performance of the system To make effective execution of general user program To make effective utilization of human resources To make available new, better facilities

1.3 System Software What is System Software？ System Software consists of a variety of programs that support the operation of a computer. The programs implemented in either software and (or) firmware(ثابتة) that makes the computer hardware usable. The software makes it possible for the users to focus on an application or other problem to be solved, without needing to know the details of how the machine works internally.

1.4 System Software Concept Users Application Program Debugger Macro Processor Text Editor Utility Program (Library) Complier Assembler Load and Linker OS Memory Management Process Management Device Management Information Management Bare Machine (Computer)

1.5 Evolution of Components Systems Programming Reasons for the evolution (تطور)of system programs To make computer better adapted to the need of users. People wanted more assistance in the mechanics of preparing their program.

1.6 Components will discussed We will discuss about the evolution of following components of system programming Assemblers Compilers Loaders Linkers Macros Translated programs into machine language resulting machine program loaded into memory and prepared for execution

1.6.1 Assembler Initially the users were compelled مجبر) (to write their program in machine code (a series of 0 and 1). But the programmer found it difficult to write or read programs in machine code. Now the users began to use some mnemonic (symbol) for each machine instruction, which they subsequently translate into machine language.

1.6.1 Assembler Such a mnemonic machine language is called assembly language. Programs known as assembler were written to automate the translation of assembly language to machine code. The input to the assembler is called the source program and the output is a machine language translation(object program). Assembler Source program (assembly program) Machine language (Object program)

1.6.2 Loaders A loader is a system program that places programs into memory and prepares them for execution. Once the assembler produces an object program, that program must be placed into memory and executed. It is the purpose of loader to assure that object programs are placed in memory in an executable form.

1.6.3 Macros First you should know what is subroutine? A subroutine is a body of computer instruction designed to be used by other routines to accomplish a task. There are two types of subroutine: Open subroutine Close subroutine

1.6.3 Macros Open subroutine or Macros Closed subroutine Whose code is inserted in the main program(flow continues). Thus if the same open subroutine is called four times, it would appear in four different places in the calling program. Closed subroutine It can be stored outside the main routine, and control transfers to the subroutine.

1.6.3 Need Of Macros To relieve اعفاء منprogrammers of the need to repeat identical parts of their program operating system provide a macro processing facility, which permits the programmer to define an abbreviation for a part of his program and to use this abbreviation in his program. The macro processor treats the identical parts of the program defined by the abbreviation as a macro definition and saves the definition.

1.6.4 Compilers As the user’s problems became more categorized into areas such as scientific Business Statistical problems Some high level languages were developed that allowed the user to express certain problems concisely and easily. E.g. FORTRAN,COBOL,ALGOL…..

1.6.4 Compilers A compiler is a system program that accepts program written in HIGH level language and produces an object program. Modern compilers must be able to provide the complex facilities that programmers are now demanding. Compilers High level language program Machine language (Object program)

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