Interrupts In Operating Systems Computer Science Essay

Interrupts In Operating Systems Computer Science Essay To successfully control several processes the core of operating system makes utilize of what is known as interrupt. Interrupt is a machine used for implementing the multitasking concept. It is a signal from hardware or software to point out the incidence of the event. When one or more process running and at similar time if user give an additional process then interrupt is take place. If the CPU does not poll the control bit, but instead receives an interrupt when the device is ready for the next byte, the data transfer is said to be interrupt driven. A hardware interrupt occurs, when an I/O operation is done such as analysis some data into the computer from a tape drive. In additional term hardware interrupts are used by devices to communicate that they need awareness from the operating system. Some familiar examples are a hard disk signaling that is has read a sequence of data blocks, or that a network device has processed a buffer containing network packets. Interrupts are also worn for asynchronous events, such as the appearance of new data from an exterior network. Hardware interrupts are delivered straight to the CPU via a little network of interrupt administration and routing devices. Hardware interrupts are referenced by an interrupt numeral. These statistics are mapped back to the section of hardware that produced the interrupt. This enables the system to monitor which device formed the interrupt and when it occurred. In most computer systems, interrupts are handled as speedily as possible. When an interrupt is acknowledged, any recent action is blocked and an interrupt handler is executed. The handler will anticipate any supplementary running programs and system actions, which can time-consuming the entire system down, and generate latencies. MRG Real-time modifies the way interrupts are handled in array to progress performance, and reduce latency. Software interrupts A software interrupt occurs when an application program terminates or needs definite services from the operating system. Software interrupt generated contained by a processor by executing an instruction. Software interrupt are frequently used to implemented system calls because they implemented a subroutine call with a CPU ring stage modify. Timed interrupts The timed interrupt is worn when a convinced event MUST happen at a specified frequency. Interrupt vector   An  interrupt vector  is the  memory address  of an  interrupt handler, or directory into a group called an  interrupt vector table  or  dispatch table. Interrupt vector tables include the memory addresses of interrupt handlers. When an interrupt  is generated, the processor saves its completing state through a  context switch, and begins effecting of the interrupt handler at the interrupt vector. Answer 2 Microkernel A Microkernel tries to run the majority services like networking, file system, etc. All thats left to do for the kernel are essential services, like memory allocation, scheduling, and messaging (Inter Process Communication). IPC Hardware Server S/W Kernel In theory, this model makes the kernel additional receptive (since a large amount of functionality resides in traceable user-space threads and processes, removing the require for context-switching into the kernel proper), and improves the constancy of the kernel by reducing the quantity of code running in kernel space. There are also supplementary benefits for OS that carry multi-CPU computers (much simpler reentrancy security and better correctness for asynchronous functionality) and distributed OS (code can use services without knowing if the service contributor is running on the similar computer or not). A disadvantage is the sum of messaging and Context Switching concerned, which makes microkernels conceptually slower than monolithic kernel. Modular Kernel A modular kernel is an effort to combine the excellent points of kernel-level drivers and moderator drivers. In a modular kernel, a few part of the system core will be situated in autonomous files called modules that can be additional to the system at run time. Depending on the substance of those modules, the aim can differ such as: just loading drivers if a device is in fact establish only load a file system if it gets really requested, just load the code for a precise scheduling, security or any policy when it should be evaluated. Modular and layered kernel compare and contrast The modular kernel approach requires subsystems to interrelate with each other through suspiciously constructed interfaces that are naturally narrow (in conditions of the functionality that is showing to external modules). The layered kernel moves toward is similar in that admiration. However, the layered kernel imposes a firm ordering of subsystems such that subsystems at the subordinate layers are not allowed to appeal to operations parallel to the upper-layer subsystems. There are no such limitations in the modular-kernel approach, wherein modules are open to invoke each other not including any constraints. Answer 3 What is a context switch? Context switching occurs when single  process  provisionally discontinues execution and an additional  process  resumes execution in its position. Context switching is performed by the  scheduler. To give each process on a multi-programmed machine a light contribute to of the CPU, hardware clock generates interrupts every so often. This allows the operating system to program every process in core memory (via scheduling algorithm) to run on the CPU at the same intervals. Every time a clock interrupt occurs, the interrupt handler checks how much time the recent running process has used. If it has used up its total time segment, then the CPU scheduling algorithm (in kernel) picks a dissimilar process to run. Each switch of the CPU from one process to a new is called a context switch. What actions are taken by a kernel to context switch? Actions are taken by a kernel to context switch surrounded by threads. The threads contribute to a lot of resources with more peer threads belonging to the equal process. So a context switch along with threads for the similar process is effortless. It involves switch of register position, the program counter along with the stack. It is comparatively easy for the kernel to achieve this task. Actions are taken by a kernel to context switch among Processes. Context switches among processes are exclusive. Ahead of a process can be switched its PCB (process control block) should be saved by the operating system. The PCB consists of the subsequent information: The process state, the program counter, the principles of the different registers, The CPU scheduling information for the process, Memory organization information concerning the process, Possible accounting information for this process, I/O status information of the process. When the PCB of the presently executing process is saved the operating system loads the PCB of the subsequently process that has to be performing on CPU. This is an important job and it takes a lot of time. Answer 4 System calls System calls are functions that a programmer can call to perform the services of the operating system. Processes that run in user mode and how processes and libraries can cause execution in kernel mode. The interface between these two modes is provided by  system calls. These are function calls that cause requests to be made to the kernel and the kernel to execute on behalf of those requests. Commands   UNIX System Calls   Libraries   File Formats   Games   Device Drivers   System Maintenance   System calls implemented by an operating system User cannot execute privileged instructions. Users must ask OS to execute them system calls. System calls are often implemented using traps. OS gains control through trap, switches to supervisor model, performs service, switches back to client mode, and gives control back to client. Dual mode The dual mode operation provides us with the resources for protecting the operating system from erroneous users. User mode and monitor mode are the two modes. Monitor mode is also called superintendent mode, system mode or privileged mode. Mode bit is attached to the hardware of the computer to point toward the present mode. In argument 0 mode bit is for monitor mode and 1 mode bit is for user mode. Application programming interface An application program interface is the precise technique set by a computer  operating system  or by an  application program  by which a programmer scripting an application program can create requirements of the operating system or a different application. An application program interface can be contrasted with a  graphical user interface  or a  command interface (both of which are direct  user interface) as interfaces to an operating system or a program. For example: Network application programming interface (API) The services that provide the interface between application and protocol software. Application Network API Protocol A Protocol B Protocol C Different methods of passing data to the operating system In a computer system having variety of memory address spaces, such as user space and kernel space, a technique and system is provided for communicating data. A data structure is distinct in the kernel space to stock up data. The data structure is nearly mapped to an application in user space such that the application can contact the data structure via virtual memory addresses. By directly accessing the data structure, data transfers between the address spaces using system calls and interrupts can be reduced. Answer 5 What is Process Scheduling? Process scheduling is a method that is used when there are limited assets and many processes are competing for them; Multiprogramming tries to make sure that there is a number of process running at all times. This is completed to utilize the CPU as much as possible. In timesharing system, the CPU switches so regularly between jobs grey_loader that the user does not experience that the machine is being mutual by many processes or even several users. What are the differences between short-term, medium-term, and long-term scheduling? Long term scheduler determines which programs are admitted to the system for processing. It controls the degree of multiprogramming. Once admitted, a job becomes a process. Medium term scheduling is division of the exchange utility. This relate to processes that are in a blocked or suspended state. They are swapped out of real-memory until they are prepared to execute. The swapping-in decision is based on memory-management criteria. Short term scheduler, also known as a dispatcher executes most regularly, and makes the finest-grained conclusion of which process should execute subsequently. This scheduler is invoked whenever an occasion occurs. It may direct to interruption of one process by pre-emption. Process state The state of process is distinct in fraction by the present activity of the process. Each process may be in one of the following states: New Running Waiting Ready Terminated These state names are random, and they differ across operating systems. The states that they correspond to are establishing on all operating systems, however. Certain operating systems more finely describe process states. Only one process can be running on any processor at any immediate, although numerous processes may be ready and waiting.

Infomatics Needs Assessment Essay

Changes in healthcare and advancements in technology have allowed for new and exciting opportunities to intergrade in the two fields. The government has supported healthcare facilities during this transition since 2009, by providing stimulus money to assist in the transition from paper to electronic medical records (EMR). The Obama administration will start fining healthcare facilities that have not made this transitioned to EMRs by 2015. In order to take advantage of this opportunity and to avoid fines, we must heed this mandate. Many facilities are finding it difficult to find the right system for their work places. This proves the importance of a needs assessment. â€Å"A needs assessment is a systematic set of procedures that are used to determine needs, examine their nature and causes, and set priorities for future action.† Need for Needs Assessment A needs assessment is an integral and necessary part to implementing change. Preforming this assessment will save money by preventing facilities from spending money on needless changes. During the process it is determined if there really is a need for this change. It also can provide alternative options if the original plan was found to be suboptimal. If the assessment determines that the plan for change is appropriate, the assessment will help set priorities and determine how to allocate resources such as people, money and facilities. Important considerations There are a few important aspects of this assessment that must be considered such as: definition of the need, the targeted group and consequences. During a needs assessment the â€Å"need† will have to be clearly defined. â€Å"A need is a discrepancy or gap between what is and what should be.† For the purposes of healthcare the gap is between paper medical records and electronic medical records. The targeted group most also be defined to ensure that the need fits the group. The question; is this a critical  change? Must be answered. Finally, the consequences for misfortune must also be addressed. In healthcare the facility must consider the consequences if implementation of the electronic medical record failed. They would be at a great finical loss. Collection of data Data from internal and external environment must be collected. Internal data can be collected from employees, and current technology. Employees can be interviewed for data or the facility can request surveys be filled out. External data can be collected from published literature, information from vendors, regulatory and accreditation requirements, information trending, and organizations like HIMSS or KLAS. HIMSS. Health care information and management systems, vision is to improve health care through incorporation of information technology. KLAS is an organization that collects feedback about healthcare systems and produces ratings. Both these organization can help narrow down the electronic medical record that will fit this facility. Members involved in needs assessment During the assessment the people affected should be consulted and directly involved in both the needs assessment and the designing of the program. In healthcare, doctors and nurses should be involved because they will be using the systems. Unit manger will be able to give a unique perspective to help with the functionality of the system and will also be able to boost morale regarding the change. Finally, the designers of the system should be included in the conferences with all other stakeholders. It is important the designers are present to help keep expectation as close to reality as possible. Conclusion All medical facilities are faced with the need to implement an electronic medical record in the upcoming years. It is important that this facility finds the right system the first time to avoid unnecessary finical loss. Preforming a needs assessment is the best way to aid in making the best decision. References (n.d.). Retrieved March 16, 2015, from http://www2.ed.gov/admins/lead/account/compneedsassessment.pdf Why Is Assessment Important? (n.d.). Retrieved March 16, 2015, from http://www.edutopia.org/assessment-guide-importance DeSilets, Lynore D, EdD,R.N., B.C. (2006). Needs assessment. The Journal of Continuing Education in Nursing, 37(4), 148-9. Retrieved from http://search.proquest.com/docview/223317102?accountid=458 Hebda, T., & Czar, P. (2013). Handbook of informatics for nurses & healthcare professionals (5th ed.). Boston: Pearson. KLAS Helps Healthcare Providers by Measuring Vendor Performance. (n.d.). Retrieved March 17, 2015, from http://www.klasresearch.com/ HIMSS – Healthcare Information and Management Systems Society. (n.d.). Retrieved March 17, 2015, from http://www.himss.org/ Jackson, D. (2013, September 23). Most health care records now are electronic. Retrieved March 17, 2015, from http://www.usatoday.com/story/news/politics/2013/07/16/obama-electronic-health-care-r ecord-keeping/2521217/

African American Literature - 2022 Words

African-American Influence on American literature African American literature can be summarized as the writings of authors from African descent. In the United States, African descendents have had very different experiences from each others depending on where they lived. In the southern states of the United States, Blacks have been really oppressed until the Civil War, with the big part being illiterate well into the end of 1800. In the northern states ,Blacks had a considerable greater freedom, and with the end of the Civil War, a new and educated African American social class emerged. African American literature was influenced by these factors, and it varied greatly but it always held undeniable similarities, circling the Black†¦show more content†¦It became obvious to the African American population that they would not be able to equalize themselves with the White population, simply because they were not equals. Blacks had a strong sense of heritage that was linked to Africa, and their history in America had worked to make them into different Americans, with their own particular desires, folklore and culture. It was only in the 1920s that a new literature genre that had been appearing gradually would be classified and identified as an African-American literature. The movement that promoted this new notion of a literature that had its foundation built on the African American experience was the Harlem Renaissance. The Harlem Renaissance marked a historical period in African American history. This movement offered the African American community an active voice, a way through which the African American community could for the first time transport to the greater America their history, life, culture and afflictions. The most important publishers and critics for the first time took African American literature seriously, and with this recognition came national attention and notoriety. No longer was the rich African American literature for his own community, this literature gained momentum and established the African American community as part of America. The Harlem Renaissance was made poss ible by a change in the social status of African Americans.Show MoreRelatedAfrican American Literature And Literature Essay1957 Words   |  8 PagesAfrican American literature  is the body of work produced in the  United States  by writers of African descent. This particular genre traces back to the works from the late eighteenth century by writers such as  Phillis Wheatley to later reaching early high points with slave narratives and the Harlem Renaissance, and thus continuing today with authors such as  Colson Whitehead and Maya Angelou. 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Want to Know How to Read College Textbooks Ask the Students!

Throughout their college years, students deal with lots of reading assignments. The amount of reading often exceeds the time resources that students have. Fortunately, they know how to cut the costs on college textbooks because there are a lot of them to buy. You might think at first that, in order to be successful and get good grades, you should buy and read everything you’re assigned. Instead, the real academic success depends not on how much you read, but on how much important information you get from reading. While your professors insist that you should read everything, smart students understand that it isn’t the way to learn. In this article, we’ll take a look at some tips from smart students on how to deal with a lot of reading without having to read absolutely everything. The trick is to get the juice out of your textbook and to do it as efficiently as possible. Starting the Chapter First of all, right before reading the assigned chapter, try to pay attention to the objectives at the beginning of the chapter. Then go to the summary or the key points at the end of this chapter. The objectives will tell you what you should focus on the most, and the summary points will suggest what exactly you should know to be prepared for the class or the upcoming test. Everything That Stands out When you’ve done with the objectives and the summary, it’s time to tackle the chapter itself. When reading the body of the chapters, you shouldn’t pay attention to the entire text. It is better to concentrate on everything that â€Å"stands out†. That would be paragraph titles and subtitles, bolded terms and new concepts, or italicized fragments of text. Read Graphs and Tables Next, here is one really important tip —  pay attention to the visuals. Textbooks are often stuffed with visual information in the form of graphs, charts, tables, or pictures. They often contain something important or help you understand the material better. What’s more, they are always explained below through the means of text. It basically repeats the information in a graph. So, read the graphs and skip those large pieces of text which explain the visuals. The First Two Sentences Textbooks are structured in a very formal way. That is the one that obliges us to start each paragraph with the topic sentence. It is, in fact, the most important element of the paragraph: it states the main issue discussed in this paragraph. The second sentence usually provides an explanation. In case the information you’ve obtained from those two sentences was not enough for you to understand the chapter, you might want to read the entire chapter in order to get a whole picture and to be better prepared for the class. Take Notes Taking notes is essential for those who want to practice active reading, rather than passive reading. Reading actively means that you’re interacting with the text. Don’t just write down exactly what you see in the book; always paraphrase it in your own words. This tip is especially helpful when you are doing a writing assignment based on the textbook you need to read. Despite the fact that most time-saving techniques and strategies help you become more efficient in your studies, they do not help in absolutely every case. When you read your textbook and skip through the main points, it is always better to spend a little more time on some extra reading than missing the point altogether. In other words, you should always look forward to saving some time, but you should also be prepared to your tests and exams. Always make sure that you are actually learning, not just reading.