Jobs residing in mass storage wait for execution in a job queue. A queue is a storage organization in which objects are ordered in first in first-out fashion. That is, objects are removed from the queue in the order they arrived.In early operating systems, each job was accompanied by a series of instructions explaining the steps required to prepare the machine for this particular job. Those instructions were written using a system known as JCL (Job Control Language) and stored with the job in the job queue. Major drawback – no interaction once the job has been submitted for execution.
Interactive operating systems allow programs being executed to carry an dialogue with the user through terminals. Terminals – some “dummy” display based typewriters allowing the user to issue commands and receive responses. Today they evolved to complex machines (even stand alone machines).
Trends and technologies in system softwares
TRENDS AND TECHNOLOGIES INSYSTEM SOFTWARE
• Introduction• What are the system software in practice?• Operating systems.• Utility software.• Loaders, Linkers and decoders.• Compilers.AGENDA
INTRODUCTION Invitation to Computer3 Science, C++ Version, Fourth Edition
• System software • Acts as an intermediary between users and hardware • Creates a virtual environment for the user that hides the actual computer architecture• Virtual machine (or virtual environment) • Set of services and resources created by the system software and seen by the userSystem Software: TheVirtual Machine Invitation to Computer4 Science, C++ Version, Fourth Edition
Figure 6.1 The Role of System Software 5Invitation to Computer Science, C++ Version, Fourth Edition
• System software is a collection of many different programs• Operating system • Controls the overall operation of the computer • Communicates with the user • Determines what the user wants • Activates system programs, applications packages, or user programs to carry out user requestsTypes of System Software Invitation to Computer6 Science, C++ Version, Fourth Edition
Figure 6.2 Types of System Software 7Invitation to Computer Science, C++ Version, Fourth Edition
• User interface • Graphical user interface (GUI) provides graphical control of the capabilities and services of the computer• Language services • Assemblers, compilers, and interpreters • Allow you to write programs in a high-level, user-oriented language, and then execute themTypes of System Software(continued) Invitation to Computer8 Science, C++ Version, Fourth Edition
• Memory managers • Allocate and retrieve memory space• Information managers • Handle the organization, storage, and retrieval of information on mass storage devices• I/O systems • Allow the use of different types of input and output devicesTypes of System Software(continued) Invitation to Computer9 Science, C++ Version, Fourth Edition
• Scheduler • Keeps a list of programs ready to run and selects the one that will execute next• Utilities • Collections of library routines that provide services either to user or other system routinesTypes of System Software(continued) Invitation to Computer10 Science, C++ Version, Fourth Edition
• The three major functions of system software are• 1. Allocating system resources• 2. Monitoring system activities• 3. File and disk managementFunctions Of System Software Invitation to Computer11 Science, C++ Version, Fourth Edition
• Linkers and loaders have been part of the software toolkit almost as long as there have been computers, since they are the critical tools that permit programs to be built from modules rather than as one big monolith.• Linker is a program that takes one or more objects generated by a compiler and combines them into a single executable program. Usually large applications are written into small modules and are then compiled into object codes. A linker is a program that combines these object modules to form an executable.LINKER AND LOADER
• As early as 1947, programmers started to use primitive loaders that could take program routines stored on separate tapes and combine and relocate them into one program.• By the early 1960s, these loaders had evolved into full- ﬂedged linkage editors.• During the 1970s and 1980s there was little progress in linking technology. This is due to the arrival of virtual memory.• In the 1990s linkers have again become more complex, adding support for modern features including dynamically linked shared libraries.CONT
• Loader is utility program which takes object code as input prepares it for execution and loads the executable code into the memory. Thus loader is actually responsible for initiating the execution process.Functions of Loader: The loader is responsible for the activities such as allocation, linking, relocation and loading 1)It allocates the space for program in the memory, by calculating the size of the program. This activity is called allocation.LOADER
2) There are some address dependent locations in theprogram, such address constants must be adjustedaccording to allocated space, such activity done byloader is called relocation.3) Finally it places all the machine instructions and dataof corresponding programs and subroutines into thememory. Thus program now becomes ready forexecution, this activity is called loading.CONT
Utility software is system software designed to help analyze, configure, optimize or maintain a computer. A single piece of utility software is usually called a utility or tool. Utility software usually focuses on how the computer infrastructure (including the computer hardware, operating system, application software and data storage) operates.UTILITY SOFTWARE
UTILITY SOFTWARE CATEGORIESAnti-virus utilities scan for computer viruses.Backup utilities can make a copy of all information stored on a disk, and restore either the entire disk (e.g. in an event of disk failure) or selected files (e.g. in an event of accidental deletion).Data compression utilities output a shorter stream or a smaller file when provided with a stream or file.Disk checkers can scan operating hard drive.Disk cleaners can find files that are unnecessary to computer operation, or take up considerable amounts of space. Disk cleaner helps the user to decide what to delete when their hard disk is full.Disk compression utilities can transparently compress/uncompress the contents of a disk, increasing the capacity of the disk.
• Disk defragmenters • Hex editors• Disk partitions • Memory testers• Disk space analyzers • Network utilities• Disk storage • Registry cleaners• Archive • Screensavers• File managers • System monitors• Cryptographic • System profilers
• Microsoft software utility first introduced with Windows 98 and included with all other versions of Windows released after it that enables users to configure how their computer starts and what programs or services automatically load each time the computer starts.• Users running these versions of Windows can open msconfig by following the below steps. • Click Start and Run. • Type msconfig and press enter, once done you should see the System Configuration Utility window as shown in the below example picture.MICROSOFT UTILITY SOFTWARE
CCleaner (formerly Crap Cleaner), developed by Piriform, is a utility program used to clean potentially unwanted files and invalid Windows Registry entries from a computer.A public version 1.01 for the Mac OS X has been released along with a Network Edition.CCleaner can be employed to uninstall programs.CCleaner allows the alteration of start-up programs, similar to the Microsoft Windows MSConfig utility.Users can disable start-up programs.As of version 2.19.901, CCleaner also allows users to delete system restore points.
CCLEANERDeveloper(s) :PiriformInitial release :23 September 2003; 8 years ago Stable release :3.20.1750 / 25 June 2012; 10 days agoOperating system : Windows 2000 and later Mac OS X 10.5 and laterPlatform :IA-32 and x64Available in :47 languagesType :Utility softwareLicense :FreemiumWebsite :www.piriform.com/ccleaner
OPERATING SYSTEM• Operating System is a software, which makes a computer to actually work.• It is the software the enables all the programs we use.• The OS organizes and controls the hardware.• OS acts as an interface between the application programs and the machine hardware.• Examples: Windows, Linux, Unix and Mac OS, etc.,
• Batch processing• Interactive processing • Requires real-time processing• Time-sharing/Multitasking • Implemented by Multiprogramming• Multiprocessor machinesEvolution of SharedComputing
• Users seeking services from same machine at the same time – time sharing • Implemented using a technique called multiprogramming (time is divided into multiple intervals, execution of one job is limited to a single time interval)• Multiple terminals connected to same machine • Driven by the fact that in the past computers were very expensive• When multiprogramming is applied to single- user environments is usually called multitaskingTime Sharing / Multitasking
• Provide time sharing/multi-tasking capabilities by assigning different tasks to different processors as well as sharing the time of one single processor• Problems to solve: • Load balancing – dynamically allocating tasks to the various processor so that all of them are used efficiently • Scaling – breaking tasks into sub-tasks compatible with the number of processors available• Trend to develop a network wide operating system rather than networks of individual operating systemsMultiprocessor OperatingSystems
• Used in hand held devices (PDAs), mobile phones, cars, etc…• Limited data storage and power conservation are the big challenges.• Examples: VxWorks, Windows CE (Pocket PC), Palm OS, Symbinan, ThredX, RomDOS, etc…Embedded OperatingSystems
• Many people are not satisfied with proprietary operating system.• As Linux is a open source operating system, they develop their own kernal and other applications for their system.Open source operating system
NEXT GENERATION• In future the microsoft is deciding to develop cloud OS.• They decided to develop Operating System integrated with browser.• Many OS like Google Chrome OS, Firefox OS is coming up.
• A compiler is a computer program that transforms source code written in one programming language (the source language), into another programming language (the target language, often having a binary form known as object code).• The history of the compilers takes us to the early 1940’s.COMPILERS
• In 1945- Konrad Zuse began work on Plankalkul (Plan Calculus), the first algorithmic programming language, with an aim of creating the theoretical preconditions for the formulation of problems of a general nature.• In 1948- Claude Shannon´s "The Mathematical Theory of Communication" showed engineers how to code data so they could check for accuracy after transmission between computers. • Shannon identified the bit as the fundamental unit of data and, coincidentally, the basic unit of computation.COMPILERS- History
• The term compiler was coined by Hopper.• The first compiler was written by Grace Hopper, in 1952, for the A-0 System language.• The A-0 System was a set of instructions that could translate symbolic mathematical code into machine language.COMPILERS- Birth
• In 1953- John Backus completed speedcoding for IBM´s 701 computer. Although speedcoding demanded more memory and compute time, it trimmed weeks off of the programming schedule.• One of the first real compilers was the FORTRAN compiler of the late 1950s.COMPILERS- History
• During the late 1970s and early 1980s, optimizing compilers continued to improve to the point that all but the most critical portions of general-purpose programs were written in high-level languages.• On the average, the compilers generate better code than most assembly language programmers. This was often because a compiler could make better use of hardware resources such as registers.COMPILERS- History
• In 1953- John Backus completed speedcoding for IBM´s 701 computer. Although speedcoding demanded more memory and compute time, it trimmed weeks off of the programming schedule.• ALGOL 58 for Z22 computer.• ALTAC (extended Fortran compiler) was also available on the Philco 2000COMPILERS- History
• Self-hosting Compilers:• A bootstrapping problem: First, such compiler for a language must be compiled either by a compiler written in a different language. • The first self-hosting compiler (excluding assemblers) was written for Lisp by Hart and Levin at MIT in 1962. • They wrote a Lisp compiler in Lisp, testing it inside an existing Lisp interpreter.• Open source compilers.COMPILERS- History
Rob Walling- “The Future Of Compilers”(www.softwarebyrob.com/2006/04/27/)• Reaching the point of employing Artificial Intelligence (AI) in an attempt to see the future.• Compilers operate with no a priori knowledge of the code beyond the language syntax definitions.• Determining how a person, file or database is going to interact with an application until it actually happens.• This problem is hard, but not unsolvable.COMPILERS- Future
• It started with huge multi-pass designs for COBOL and FORTRAN.• Then we moved into block-structured languages (algol, pascal, and even C).• Then we moved into OOP: C++, Java, .NET.• Some IDEs now use parsers to validate syntax/semantics as programs are entered. • This started with legacy Quickbasic, but QB was using it to do part of compilation as users entered each line (because PCs were slow)CONCLUSION