Functions And Classification Of Operating Systems Essay Example

Functions And Classification Of Operating Systems Essay Example Functions And Classification Of Operating Systems Essay Functions And Classification Of Operating Systems Essay The OS is the system package that controls the overall operation of the computing machine system. It manages the affiliated hardware, provides a platform to run application plans and an interface for users to interact with the computing machine system. It is responsible for recognizing and organizing memory devices, I/O devices and treating devices. Figure 10.1 displays the function of OS in the computing machine system. An OS provides two types of interfaces: Graphical User Interface ( GUI ) and Command Line Interface ( CLI ) . An OS responds and provides services to the users. Figure 10.1: Functions of OS in the Computer System 10.1.1 Functions of OS : An OS is the indispensable package in the computing machine system. It performs several undertakings to maintain the application package, hardware devices and users of the computing machine system coordination. The OS performs the undermentioned maps: Information Management Information direction refers to the set of services used for recovering, hive awaying, modifying and canceling informations from devices. It has two subsystems, file direction and I/O direction. Process Management Procedure direction is responsible for administering CPU clip between procedures. It besides involves pull offing memory and I/O resources across the procedure in the computing machine system. Memory Management Memory direction controls memory use. At any given case, memory direction keeps path available infinite to hive away the information. Application Programing Interface ( API ) The API assigns entree to application package on all connected hardware devices. User Interface User Interface provides interaction between the computing machine system and users. 10.2 Development of OS Operating systems evolved in seven stages. The six stages viz. unfastened store, batch processing, concurrent execution, timesharing, personal computer science and distributed systems, changed the manner users accessed the OS. Concurrent programming brings multiple innovations to do resource direction effectual. Table 10.2 shows stages and proficient development of an OS. An development of OS started from 1954, when Computer system had non OS, users use to run computing machine system manually. Phases of OS development of are as follows: Open Shop Open Shop introduced IBM 701 that was implemented the on celebrated IBM 701 machine. First user has to do apparatus as per the demand for each computer science. However, in this stage clip and money wasted in puting up machine manual. Users got fixed clip for calculating, although most of the clip was spent puting up the machine manually. Batch Processing Wastage of clip and money in the unfastened store stage was a consequence of user engagement. In this stage, it was clear that normal users were to be kept off from the calculating procedure. This stage besides revealed that the OS was capable of scheduling. Normal users put their occupations on a clout card merely to be processed by computing machine professionals subsequently. The BKS system was the released in this stage. Multiprogramming The aim of concurrent execution was to maintain the CPU every bit busy as possible to use its processing capacity wholly. At the initial phase of multiprogramming stage, the thought was to maintain following plan ready in the memory from where the CPU could take it up instantly. However, in the same stage, hardware interrupts were introduced. Hardware interrupts facilitated shift of procedures. The construct of hardware interrupts made multiprogramming more successful. It besides permitted I/O devices and treating devices to work at the same time. This procedure was called coincident peripheral operation on-line. The constructs of job-scheduling, demand paging, practical memory were introduced in the same stage. Atlas supervisor, B5000 system, Exec II system and Egdon systems were introduced in the concurrent execution stage. Time Sharing Time-sharing allowed processors to go to to petitions from other users while one user was busy executing some I/O map. This manner the CPU could go to to multiple procedures every bit good as users in lesser clip spans. CTSS, Multics File system, Titan File system and UNIX were introduced in this stage. Concurrent The concurrent stage introduced the characteristic of running multiple undertakings at a clip called as multitasking. THE system, RC 4000 system, Venus system, Boss 2 system, Solo system, and Solo Program Text, were the concurrent OS introduced back so. Personal Computing In the personal computer science stage of development, user convenience was on the precedence than recourse direction. The GUI based OS and mouse based interactivity were introduced in this stage merely. OS, Alto system, Pilot system and star user interface were introduced in this stage. Distributed Systems This stage includes computer-networking constituents that enable message go throughing within computing machines and distant process call. WFS File waiters, Unix United RPC, Unix United system and Amoeba systems were launched in this stage. Phase Technical Development Operating System Phase 1: Open Shop An thought of operating systems 1. IBM 701 unfastened store ( 1954 ) Phase 2: Batch Processing Tape batching First-In First-Out and scheduling 2. BKS system ( 1961 ) Phase 3: Multiprogramming Processor multiplexing, Indivisible operations, Demand paging, Input/output spooling, Priority programming and Distant occupation entry 3. Atlas supervisor ( 1961 ) 4. B5000 system ( 1964 ) 5. Exec II system ( 1966 ) 6. Eldon system ( 1966 ) Phase 4: Timesharing Coincident user, interaction and On-line file systems 7. CTSS ( 1962 ) 8. Multics File system ( 1965 ) 9. Titan File system ( 1972 ) 10. Unix ( 1974 ) Phase 5: Concurrent Programing Hierarchical systems, Extensile meats, Parallel programming constructs and Secure analogue linguistic communications 11. THE system ( 1968 ) 12. RC 4000 system ( 1969 ) 13. Venus system ( 1972 ) 14. Boss 2 system ( 1975 ) 15. Solo system ( 1976 ) 16. Solo plan text ( 1976 ) Phase 6: Personal Computer science Graphic user interfaces 17. OS 6 ( 1972 ) 18. Alto system ( 1979 ) 19. Pilot system ( 1980 ) 20. Star user interface ( 1982 ) Phase 7: Distributed Systems Distant waiters 21. WFS File waiter ( 1979 ) 22. Unix United RPC ( 1982 ) 23. Unix United system ( 1982 ) 24. Amoeba system ( 1990 ) Table 10.1: Development of OS 10.3 OS Kernel and shell Every OS consists of a meat and shell. The shell is the user interface, either a CLI or a GUI. This allows the user to login and utilize the computing machine system. The meat is the nucleus of an OS. The OS meat is more complex and is hard to work with straight, therefore the meat is wrapped in a shell A meat consists of the followers: File Manager- A file director provides interface for user to work with file. It performs actions on files such as create, edit, rename, unfastened, edit and so on.. In add-on, it maintains size and permissions about files that are available on the system. Device Driver . Device driver is a plans that controls a specific hardware devices. Each device has alone driver that converts user petition for device to specific cryptography. Memory Manager The memory director responsible for optimal use of the system memory. It allocates and de-allocates memory for hive awaying informations and plans. Scheduler- The scheduler maintains records of present procedures put to deathing by the OS and adds new procedures to the OS. Dispatcher The starter manages procedures. It divides clip into little part such as 50 second, when the clip part is over ; dispatcher allows following procedure to run. 10.4 Categorization of OS Oss have been classified based on parametric quantities such as figure of users that at the same time used the computing machine system, the figure of procedure that OS performs at a clip, and the figure of togss that OS can manage at a clip. The categorization is as follows: Single-User A single-user operating system allows merely one user to login the computing machine system. Single-user OS are intended for place users merely. Multi-user Thie multi-user OS allows multiple users to login and use the computing machine system. In this instance, the OS allocates different resources for each user so that any a job with one user does non impact other users. Single-task The single-task OS permits merely one procedure to run at a clip. Multi-tasking The multi-tasking OS permits multiple plans to put to death at the same clip. Users can run more than one undertaking at a clip. However, as multiple procedures runs at the same clip, this type of OS requires more memory. Multi-tasking OS semen in two theoretical accounts. They are: Time-sharing operating system -Time-sharing OSs usage algorithms to portion CPU clip between multiple procedures. This method creates an semblance that the CPU is put to deathing multiple procedures at the same time. Real-time operating system The real-time operating system is used to command industrial systems and scientific instruments. This type of OS manages computing machine system resources in a manner that specific operation should put to death in precise clip, every time.. 10.5 Operational overview On the boot, an OS makes certain that the system has the required hardware and package. When a user petitions for a resource such as IO or any application plan, the OS cheques permission and so decides whether to allow that petition or deny it. In a multi-user system, the OS agendas resources in a manner that ensures their handiness on petition. The OS records mistakes happening in the procedure. The OS should enter the mistake. The OS supports networking operations excessively. Devicess involved in OS operation are as follows: CPU A computing machine system supports several maps that should run at the same time. It might possible that multiple users are running their plans at the same case. The OS ensures that each user gets sufficient CPU clip to put to death the undertaking. Memory The OS helps users topographic point and recover informations from the primary memory. The OS besides takes attention of user informations that is stored in the secondary memory. Data in the secondary memory is brought to the primary memory on user petition. I/O devices The OS facilitates communicating with all I/O devices. It uses interrupt signals for the same. 10.6 Servicess Offered by OS The major aims of an OS are to do calculating convenient, run application plans and pull off the assorted resources. To accomplish these aims OS provide several services, they are as follows: Program Execution The OS provides users with a convenient environment to put to death plans. The user merely needs to originate plan executing while the OS takes attention of memory allotment for successful executing of the plan. I/O Operations Every procedure involves I/O operations ; nevertheless, internal I/O operations are non seeable to users. OS control all I/O operations. User may alter the default flow I/O operation, therefore for security grounds user are non involved in the I/O operation. File System Manipulation File system use, enables users to make or pull strings files in the OS environment without cognizing physical features of the device. Communicationss At times procedures need to pass on with each other to interchange information. This communicating could be between procedures put to deathing on the same computing machine or processes put to deathing on different computing machine systems. A communicating service enables computing machine system to interchange the procedure with other computing machine systems. Error Detection An mistake in the computing machine system leads to misfunctioning. The OS proctors computing machine systems for mistakes. 10.7 Chapter Review Questions GUI stands for ________________ . ( A ) Graphical User Interface ( C ) Graphical User Interaction ( B ) Group and User Interaction ( D ) None of the above Autonomic nervous system: A Which map of the OS is responsible for pull offing user s informations in the computing machine system? ( A ) Memory Management ( C ) Information Management ( B ) Process Management ( D ) Application Management Ands: Degree centigrade A __________ map allows users to interact with computing machine system. ( A ) Memory Management ( C ) Application Management ( B ) User Interaction ( D ) Information Management Autonomic nervous system: Bacillus A  ­Ã‚ ­Ã‚ ­__________phase of the OS development invents hardware interrupts. ( A ) Timesharing ( C ) Multi Programing ( B ) Concurrent Programing ( D ) None of the above Autonomic nervous system: Degree centigrade Which of the followers is an operating system s nucleus bed? ( A ) Kernels ( C ) Shell ( B ) Device Drivers ( D ) None of these Autonomic nervous system: A Which constituent of the meat maintains records of current procedures, adds new procedures, and removes complex procedures. ( A ) Device Drivers ( C ) Starter ( B ) Scheduler ( D ) None of these Autonomic nervous system: Bacillus Which of the following are theoretical accounts of multitasking OS? ( A ) Timesharing OS ( C ) Real-time OS ( B ) Thread sharing OS ( D ) Real-process OS Autonomic nervous system: A and C 8. CLI stands for ________________________ . ( A ) Command Line Interaction ( C ) Common Line Interface ( B ) Command Line Interface ( D ) Common Line Interaction Autonomic nervous system: Bacillus 9. Which service of an OS allows users to pass on with other computing machines? ( A ) Communicationss ( C ) Program Execution ( B ) Mistake Detection ( D ) I/O Operationss Autonomic nervous system: A 10. A __________component of OS kernel is responsible for pass oning with devices. ( A ) File Manager ( C ) Device Drivers ( B ) Device director ( D ) None of these Autonomic nervous system: Degree centigrade 10.7.1 Answers 1. Angstrom 2. C 3. Bacillus 4. C 5. Angstrom 6. Bacillus 7. A and C 8. Bacillus 9. Angstrom 10. C Drumhead In the chapter, Introduction to Operating System, you learnt about: OS and undertakings performed by the OS Development and categorization of OSs Different maps of the OS Servicess offered by the OS

Interesting Facts About Arsenic

Interesting Facts About Arsenic Arsenic is best known as a poison and a pigment, but it has many other interesting properties. Here are 10 arsenic element facts: Arsenics symbol is As and its atomic number is 33. It is an example of a metalloid or semimetal, with properties of both metals and nonmetals. It is found in nature as a single stable isotope, arsenic-75. At least 33 radioisotopes have been synthesized. Its most common oxidation states are -3 or 3 in compounds. Arsenic also readily forms bonds with its own atoms.Arsenic occurs naturally in pure crystalline form and also in several minerals, usually with sulfur or metals. In its pure form, the element has three common allotropes: gray, yellow, and black. Yellow arsenic is a waxy solid that converts into gray arsenic after exposure to light at room temperature. Brittle gray arsenic is the most stable form of the element.The element name comes from the ancient  Persian word  Zarnikh, which means yellow orpiment. Orpiment is arsenic trisulfide, a mineral that resembles gold. The Greek word  arsenikos means potent.Arsenic was known to ancient man and important in alchemy. The pure e lement was officially isolated in 1250 by the German Catholic Dominican friar Albertus Magnus (1200–1280). Early on, arsenic compounds were used in bronze to increase its hardness, as colorful pigments, and in medicines. When arsenic is heated, it oxidizes and releases an odor similar to that of garlic. Striking various arsenic-containing minerals with a hammer might also release the characteristic odor.At ordinary pressure, arsenic, like carbon dioxide, does not melt but sublimes directly into vapor. Liquid arsenic only forms under high pressure.Arsenic has long been used as a poison, but its readily detected. Past exposure to arsenic may be assessed by examining hair. Urine or blood tests can assay recent exposure. The pure element and all its compounds are toxic. Arsenic damages multiple organs, including the skin, gastrointestinal tract, immune system, reproductive system, nervous system, and the excretory system. Inorganic arsenic compounds are considered more toxic than organic arsenic. While high doses can cause a quick death, low-dose exposure is also dangerous because arsenic can cause genetic damage and cancer. Arsenic causes epigenetic changes, which are heritable changes that occur withou t alteration of DNA. Although the element is toxic, arsenic is widely used. It is a semiconductor doping agent. It adds a blue color to pyrotechnic displays. The element is added to improve sphericity of lead shot. Arsenic compounds are still found in certain poisons, such as insecticides. The compounds are often used to treat wood to prevent degradation by termites, fungi, and mold. Arsenic is used to produce linoleum, infrared-transmitting glass, and as a depilatory (chemical hair remover). Arsenic is added to several alloys to improve their properties.Despite the toxicity, arsenic has several therapeutic uses. The element is an essential trace mineral for proper nutrition in chickens, goats, rodents, and possibly humans. It may be added to livestock food to help the animals put on weight. It has been used as a syphilis treatment, cancer treatment, and skin bleaching agent. Some species of bacteria can perform a version of photosynthesis that uses arsenic rather than oxygen to obtain energy.The element abundance of arsenic in the Earths crust is 1.8 parts per million by weight.  Approximately a third of the arsenic found in the atmosphere comes from natural sources, such as volcanoes, but most of the element comes from human activities, such as smelting, mining (especially copper mining), and release from coal-burning power plants. Deep water wells are commonly contaminated with arsenic.