Health insurance exchange

A health insurance exchange is a set of state-regulated and standardized health care plans, from which individuals may purchase health insurance that is eligible for Federal subsidies. In the United States, it is the main thrust of the Patient Protection and Affordable Care Act.
A private health insurance exchange is an exchange run by a private sector company or private nonprofit corporation. Health plans and carriers in a private exchange must meet certain criteria defined by the exchange management. Private exchanges combine technology and human advocacy, include online eligibility verification, and mechanisms for allowing employers who connect their employees or retirees with exchanges to offer subsidies. Private exchanges are designed to help purchasers find the best possible plan value personalized to their specific health conditions and doctor/hospital networks.

Health insurance

Health insurance is insurance against the risk of incurring medical expenses among individuals. By estimating the overall risk of health care expenses among a targeted group, an insurer can develop a routine finance structure, such as a monthly premium or payroll tax, to ensure that money is available to pay for the health care benefits specified in the insurance agreement. The benefit is administered by a central organization such as a government agency, private business, or not-for-profit entity.


A health insurance policy is:

1) a contract between an insurance provider (e.g. an insurance company or a government) and an individual or his sponsor (e.g. an employer or a community organization). The contract can be renewable (e.g. annually, monthly) or lifelong in the case of private insurance, or be mandatory for all citizens in the case of national plans. The type and amount of health care costs that will be covered by the health insurance provider are specified in writing, in a member contract or "Evidence of Coverage" booklet for private insurance, or in a national health policy for public insurance.

2) Insurance coverage is provided by an employer-sponsored self-funded ERISA plan. The company generally advertises that they have one of the big insurance companies. However, in an ERISA case, that insurance company "doesn't engage in the act of insurance", they just administer it. Therefore ERISA plans are not subject to state laws. ERISA plans are governed by federal law under the jurisdiction of the US Department of Labor (USDOL). The specific benefits or coverage details are found in the Summary Plan Description (SPD). An appeal must go through the insurance company, then to the Employer's Plan Fiduciary. If still required, the Fiduciary’s decision can be brought to the USDOL to review for ERISA compliance, and then file a lawsuit in federal court.

The individual insured person's obligations may take several forms:

• Premium: The amount the policy-holder or his sponsor (e.g. an employer) pays to the health plan to purchase health coverage.
• Deductible: The amount that the insured must pay out-of-pocket before the health insurer pays its share. For example, policy-holders might have to pay a $500 deductible per year, before any of their health care is covered by the health insurer. It may take several doctor's visits or prescription refills before the insured person reaches the deductible and the insurance company starts to pay for care.
• Co-payment: The amount that the insured person must pay out of pocket before the health insurer pays for a particular visit or service. For example, an insured person might pay a $45 co-payment for a doctor's visit, or to obtain a prescription. A co-payment must be paid each time a particular service is obtained.
• Coinsurance: Instead of, or in addition to, paying a fixed amount up front (a co-payment), the co-insurance is a percentage of the total cost that insured person may also pay. For example, the member might have to pay 20% of the cost of a surgery over and above a co-payment, while the insurance company pays the other 80%. If there is an upper limit on coinsurance, the policy-holder could end up owing very little, or a great deal, depending on the actual costs of the services they obtain.
• Exclusions: Not all services are covered. The insured are generally expected to pay the full cost of non-covered services out of their own pockets.
• Coverage limits: Some health insurance policies only pay for health care up to a certain dollar amount. The insured person may be expected to pay any charges in excess of the health plan's maximum payment for a specific service. In addition, some insurance company schemes have annual or lifetime coverage maximums. In these cases, the health plan will stop payment when they reach the benefit maximum, and the policy-holder must pay all remaining costs.
• Out-of-pocket maximums: Similar to coverage limits, except that in this case, the insured person's payment obligation ends when they reach the out-of-pocket maximum, and health insurance pays all further covered costs. Out-of-pocket maximums can be limited to a specific benefit category (such as prescription drugs) or can apply to all coverage provided during a specific benefit year.
• Capitation: An amount paid by an insurer to a health care provider, for which the provider agrees to treat all members of the insurer.
• In-Network Provider: (U.S. term) A health care provider on a list of providers preselected by the insurer. The insurer will offer discounted coinsurance or co-payments, or additional benefits, to a plan member to see an in-network provider. Generally, providers in network are providers who have a contract with the insurer to accept rates further discounted from the "usual and customary" charges the insurer pays to out-of-network providers.
• Prior Authorization: A certification or authorization that an insurer provides prior to medical service occurring. Obtaining an authorization means that the insurer is obligated to pay for the service, assuming it matches what was authorized. Many smaller, routine services do not require authorization.
• Explanation of Benefits: A document that may be sent by an insurer to a patient explaining what was covered for a medical service, and how payment amount and patient responsibility amount were determined.

Prescription drug plans are a form of insurance offered through some health insurance plans. In the U.S., the patient usually pays a copayment and the prescription drug insurance part or all of the balance for drugs covered in the formulary of the plan. Such plans are routinely part of national health insurance programs. For example in the province of Quebec, Canada, prescription drug insurance is universally required as part of the public health insurance plan, but may be purchased and administered either through private or group plans, or through the public plan.

Some, if not most, health care providers in the United States will agree to bill the insurance company if patients are willing to sign an agreement that they will be responsible for the amount that the insurance company doesn't pay. The insurance company pays out of network providers according to "reasonable and customary" charges, which may be less than the provider's usual fee. The provider may also have a separate contract with the insurer to accept what amounts to a discounted rate or capitation to the provider's standard charges. It generally costs the patient less to use an in-network provider.

Source : http://en.wikipedia.org/wiki/Health_insurance

Health care industry

The health care industry, or medical industry, is the sector of the economic system that provides goods and services to treat patients with curative, preventive, rehabilitative, palliative, or, at times, unnecessary care. The modern health care sector is divided into many sub-sectors, and depends on interdisciplinary teams of trained professionals and paraprofessionals to meet health needs of individuals and populations.

The health care industry is one of the world's largest and fastest-growing industries.[3] Consuming over 10 percent of gross domestic product (GDP) of most developed nations, health care can form an enormous part of a country's economy.

For purposes of finance and management, the healthcare industry is typically divided into several areas. As a basic framework for defining the sector, the United Nations' International Standard Industrial Classification (ISIC) categorizes the health care industry as generally consisting of:

1. hospital activities;
2. medical and dental practice activities;
3. "other human health activities"

This third class involves activities of, or under the supervision of, nurses, midwives, physiotherapists, scientific or diagnostic laboratories, pathology clinics, residential health facilites, or other allied health professions, e.g. in the field of optometry, hydrotherapy, medical massage, yoga therapy, music therapy, occupational therapy, speech therapy, chiropody, homeopathy, chiropractics, acupuncture, etc.

The Global Industry Classification Standard and the Industry Classification Benchmark further distinguish the industry as two main groups:
(1) health care equipment & services; and
(2) pharmaceuticals, biotechnology and related life sciences.

Health care equipment and services comprise companies and entities that provide medical equipment, medical supplies, and health care services, such as hospitals, home health care providers, and nursing homes. The second industry group comprises sectors companies that produce biotechnology, pharmaceuticals, and miscellaneous scientific services.

Other approaches to defining the scope of the health care industry tend to adopt a broader definition, also including other key actions related to health, such as education and training of health professionals, regulation and management of health services delivery, provision of traditional and complementary medicines, and administration of health insurance

Health care reform: Revolution or evolution - What we can do to control our destiny

(NaturalNews) Health care reform is considered by many Americans to be the most important domestic issue in America, but is it really? Indeed it is important, but is it more important than the loss of our democracy and the loss of the voice of the people? Is it more important than the pollution, poor quality food, and high levels of stress that are causing much of the epidemic of chronic diseases that now affects 50% of all Americans? Is it more important than fighting the two wars we've been engaged for such a long time? And at a much higher level, is it more important than solving the global issues of preventable disease and hunger?



We have partially awakened from our trance and are starting to address some of these issues. We're screaming about our lost rights but are feeling helpless about creating change because we don't have faith that we can make a difference as individuals. We have forgotten that the only way change ever occurs is with an idea and someone to represent it. We must remember that if it is worthy, others eventually will see and follow.

Is there hope? Is it too late? There are very worrisome signs that our government is so far out of the hands of "we the people" that it no longer does much good to "write to our Congresspeople!" In fact, even voting in many respects no longer offers much choice; does it matter in any substantive way whether you vote Democratic or Republican? Is there that much, or even any for that matter, difference between the two parties as far as corruption is concerned? Has either party come up with a solution to our health care issues that is sensible? Have we become involved with a colossal struggle characterized by politics so polarized that we have lost sight of what we're trying to accomplish. Why is it that every single Democrat votes one way and every single Republican votes the other on health care reform? Is anyone in either political party thinking for themselves? Is following political party lines more important than working together to make America a better place? Are we doomed to crumble under the weight of our own corruption as have so many empires of the past?

Perhaps Gandhi had the answer when it comes to effecting social transformation. Our natural instincts are to fight against what we believe is wrong. However, where has this gotten us? Into fights! Sometimes there is no other option, but generally, even when this works, it causes change through fear and dominance rather than inspiration. How about we behave by becoming the change we want to see? That was what Gandhi proposed. There's no fighting involved in this approach. But, it may be more difficult to change our behavior rather than do what comes so naturally to us; fighting back. Change through inspiration tends to be lasting because it comes from within and is what we choose. Change through fear and dominance may impose change, but it is not likely to be lasting because it is not our choice. It leads to revolution, not evolution.

What if we took action at the local level and engaged in community programs based on good things such as developing programs that support a healthy lifestyle? What if we began participating in local government to create policies we believe in? What if we created educational programs that teach the golden rule first, and then how to build community? What if we learned to listen and care about everyone in our community? What if we spent our dollars to achieve these goals and refused to spend them on what we don't believe in? What would happen if we took this kind of responsibility?

The answer is obvious! We'd control our destiny. We'd take back democracy without the firing of a single shot. We would become leaders rather than followers and would elect only those Congresspeople who would represent us completely. We would stay in constant contact with our elected officials and participate in all governmental decisions. We'd eliminate any corporate or private business that did not offer service as the first priority because we would not purchase their goods or services. We'd be teaching our children how to get along with one another and live in community. We'd have health care that we could afford and would encourage wellness rather than react for the most part only after we get sick. In short, we'd be healthier, much happier, and make decisions that benefit our community. We'd have meaningful purpose in our lives. We'd also have far more financial resources to allocate to whatever projects we believed in.

The choice is ours: reacting to corruption with outrage, or being the change we want to see. Do you support revolution or evolution?


About the author:
Len Saputo, MD is board certified in internal medicine and is in private practice focused on integrative, holistic, person-centered care at the Health Medicine Center (http://www.doctorsaputo.com/a/healt...) in Walnut Creek, CA. Dr. Saputo is the founder of the Health Medicine Forum (http://www.doctorsaputo.com/a/healt...) and the author, with Byron Belitsos, of the Nautilus Gold Award winning book, "A Return to Healing: Radical Health Care Reform and the Future of Medicine" (http://doctorsaputo.com/a/a-return-...). He and his wife, Vicki, have hosted KEST radio's "Prescriptions for Health" show that airs daily for more than a decade.

Dr. Saputo's highly interactive health and wellness website www.DoctorSaputo.com has more than 1500 audio and video media files that are organized and targeted to address your specific and unique health issues. Take the free Health and Wellness Assessment Survey on the home page and experience how his surveys on a wide range of health care conditions provide immediate personalized integrative suggestions for your health challenges!

HHS releases new plan to prevent and treat viral hepatitis

(NaturalNews) Viral hepatitis remains a public health challenge in the United States. Approximately 3.5-5.3 million persons are living with the condition, and millions more are at risk for infection. Hepatitis, which is largely preventable, is the leading cause of liver cancer. Without appropriate care, 1 in 4 persons with chronic hepatitis will develop liver cirrhosis or liver cancer.

In January 2010, the Institute of Medicine (IOM) released a report on hepatitis, explaining the barriers to hepatitis prevention and treatment. In response to this, The U.S. Department of Health and Human Services (HHS) just released the Viral Hepatitis Action Plan -- Combating the Silent Epidemic: US Department of Health and Human Services Action Plan for the Prevention, Care and Treatment of Viral Hepatitis. The Plan is meant to result in:

- more people being aware that they have the condition
- a reduction in new cases
- a complete elimination of mother to child transmission of Hepatitis B

Although viral hepatitis is a leading cause of infectious death in the U.S., many people are unaware they have the condition because often time they don't feel the symptoms, or the symptoms are there, but just feel like the flu.

Here's a quick overview of viral hepatitis:

Hepatitis A - found in the feces of infected persons. Hepatitis A spreads from one person to another by putting something in the mouth that has been contaminated with the stool of a person with hepatitis A. This can happen when people do not wash their hands after using the toilet and then touch other people's food. Typically, milder symptoms than hepatitis B or C. Illness from hepatitis A is usually brief, and infection with the virus does not lead to chronic liver disease or liver cancer.

Hepatitis B - found in blood and certain body fluids of infected persons. Hepatitis B spreads when a person who is not immune comes in contact with blood or body fluid from an infected person. Hepatitis B is spread by having sex with an infected person without a condom, sharing needles during injected drug use, needle sticks or sharps, exposures in a health care setting, or from an infected mother to her baby during vaginal birth. Exposure to blood in any situation can be a risk for transmission. There are usually no symptoms until there are serious liver complications. When symptoms do appear, they may include high fever, jaundice and abdominal pain chronic hepatitis B can lead to cirrhosis and/or liver cancer.

Hepatitis C - also found in blood and certain body fluids of infected persons. Hepatitis C spreads when a person who is not immune comes in contact with blood or body fluids from an infected person. Hepatitis C is spread through sharing needles during injected drug use, needle sticks or sharps, exposures in a health care setting, through organ transplants that have not been screened, or less commonly from an infected mother to her baby during vaginal birth. It is possible to get hepatitis C from sex, but it is uncommon. Infection with the hepatitis C virus is the number one reason for liver transplant in the U.S. Unlike hepatitis A and B, there is no vaccine to prevent hepatitis C.

There is a simple blood test to check for the Hepatitis virus.

Hopefully, with the guidance of this plan and the collaboration of policy figures, stake holders, and health care practitioners we can reduce the transmission of this silent epidemic.

To read the action plan please see http://www.hhs.gov/ash/initiatives/...

Data source: The Racial and Ethnic Approaches to Community Health (REACH) Risk Factor Survey (www.cdc.gov/reach)
Data source: National Health and Nutrition Examination Survey (NHANES) (www.cdc.gov/nchs/nhanes.htm)

About the author:
Kshamica Nimalasuriya MD, MPH is a Preventive Medicine Physician involved with merging Media with Health, Open-Source Education, Herbal Medicine, Fitness, Nutrition, Wellness, and Love. She works on many initiatives bridging the global digital divide of health care education.

Health care system

A health care system is the organization of people, institutions, and resources to deliver health care services to meet the health needs of target populations.

There is a wide variety of health care systems around the world, with as many histories and organizational structures as there are nations. In some countries, health care system planning is distributed among market participants. In others, there is a concerted effort among governments, trade unions, charities, religious, or other co-ordinated bodies to deliver planned health care services targeted to the populations they serve. However, health care planning has been described as often evolutionary rather than revolutionary

Health policy

Health policy can be defined as the "decisions, plans, and actions that are undertaken to achieve specific health care goals within a society." According to the World Health Organization, an explicit health policy can achieve several things: it defines a vision for the future; it outlines priorities and the expected roles of different groups; and it builds consensus and informs people.



There are many categories of health policies, including personal health care policy, pharmaceutical policy, and policies related to public health such as vaccination policy, tobacco control policy or breastfeeding promotion policy. They may cover topics of financing and delivery of health care, access to care, quality of care, and health equity.

There are also many topics in the politics and evidence that can influence the decision of a government, private sector business or other group to adopt a specific policy. Evidence-based policy relies on the use of science and rigorous studies such as randomized controlled trials to identify programs and practices capable of improving policy relevant outcomes. Most political debates surround personal health care policies, especially those that seek to reform health care delivery, and can typically be categorized as either philosophical or economic. Philosophical debates center around questions about individual rights, ethics and government authority, while economic topics include how to maximize the efficiency of health care delivery and minimize costs.

Illness

Illness (sometimes referred to as ill-health or ailment) is a state of poor health. Illness is sometimes considered another word for disease. Others maintain that fine distinctions exist. Some have described illness as the subjective perception by a patient of an objectively defined disease.

The mode of being healthy includes, as defined by the World Health Organization, " [...] a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity". When these conditions are not fulfilled, then one can be considered to have an illness or be ill. Medication and the science of pharmacology is used to cure or reduce symptoms of an illness or medical conditions. Developmental disability is a term used to describe severe, life-long disabilities attributable to mental and/or physical impairments.

Physical

Conditions of the body or mind that cause pain, dysfunction, or distress to the person afflicted or those in contact with the person can be deemed an illness. Sometimes the term is used broadly to include injuries, disabilities, syndromes, infections, symptoms, deviant behaviors, and atypical variations of structure and function, while in other contexts these may be considered distinguishable categories. A pathogen or infectious agent is a biological agent that causes disease or illness to its host. A passenger virus is a virus that simply hitchhikes in the body of a person or infects the body without causing symptoms, illness or disease. Foodborne illness or food poisoning is any illness resulting from the consumption of food contaminated with pathogenic bacteria, toxins, viruses, prions or parasites.

Adaptive response

According to evolutionary medicine, much illness is not directly caused by an infection or body dysfunction but is instead a response created by the body. Fever, for example, is not caused directly by bacteria or viruses but by the body raising its normal human body temperature, which some people believe inhibits the growth of the infectious organism. Evolutionary medicine calls this set of responses sickness behavior. These include such illness defining health changes as lethargy, depression, anorexia, sleepiness, hyperalgesia, and the inability to concentrate. These together with fever are caused by the brain through its top down control upon the body. They are, therefore, not necessary, and often do not accompany an infection (such as the lack of fever during malnutrition or late pregnancy) when they have a cost that outweighs their benefit. In humans, an important factor are beliefs that influence whether the health management system in the brain that evaluates costs and benefits deploys them or not. The health management system, when it factors in false information, has been suggested to underlie the placebo reduction of illness.[8]

Mental

Mental illness (or Emotional disability, Cognitive dysfunction) is a broad generic label for a category of illnesses that may include affective or emotional instability, behavioral dysregulation, and/or cognitive dysfunction or impairment. Specific illnesses known as mental illnesses include major depression, generalized anxiety disorder, schizophrenia, and attention deficit hyperactivity disorder, to name a few. Mental illness can be of biological (e.g., anatomical, chemical, or genetic) or psychological (e.g., trauma or conflict) origin. It can impact one’s ability to work or go to school and contribute to problems in relationships. Other generic names for mental illness include “mental disorder”, “psychiatric disorder”, “psychological disorder”,“abnormal psychology”, “emotional disability”, “emotional problems”, or “behavior problem”. The term insanity is used technically as a legal term. Brain damage may result in impairment of mental function.
[edit] Study of illness

Epidemiology is the scientific study of factors affecting the health and illness of individuals and populations, and serves as the foundation and logic of interventions made in the interest of public health and preventive medicine.

Behavioral medicine is an interdisciplinary field of medicine concerned with the development and integration of psychosocial, behavioral and biomedical knowledge relevant to health and illness. Clinical Global Impression scale to assess treatment response in patients with mental disorders. It's " Improvement scale" requires the clinician to rate how much the patient's illness has improved or worsened relative to a baseline state. Mental confusion and decreased alertness may indicate that a chronic illness has gotten worse.

Disease

A disease is an abnormal condition affecting the body of an organism. It is often construed to be a medical condition associated with specific symptoms and signs.[1] It may be caused by external factors, such as infectious disease, or it may be caused by internal dysfunctions, such as autoimmune diseases. In humans, "disease" is often used more broadly to refer to any condition that causes pain, dysfunction, distress, social problems, and/or death to the person afflicted, or similar problems for those in contact with the person. In this broader sense, it sometimes includes injuries, disabilities, disorders, syndromes, infections, isolated symptoms, deviant behaviors, and atypical variations of structure and function, while in other contexts and for other purposes these may be considered distinguishable categories. Diseases usually affect people not only physically, but also emotionally, as contracting and living with many diseases can alter one's perspective on life, and their personality.

Death due to disease is called death by natural causes. There are four main types of disease: pathogenic disease, deficiency disease, hereditary disease, and physiological disease.

Diseases can also be classified as communicable and non-communicable disease.

Health Care

Health care (or healthcare) is the diagnosis, treatment, and prevention of disease, illness, injury, and other physical and mental impairments in humans. Health care is delivered by practitioners in medicine, chiropractic, dentistry, nursing, pharmacy, allied health, and other care providers. It refers to the work done in providing primary care, secondary care and tertiary care, as well as in public health.

Access to health care varies across countries, groups and individuals, largely influenced by social and economic conditions as well as the health policies in place. Countries and jurisdictions have different policies and plans in relation to the personal and population-based health care goals within their societies. Health care systems are organizations established to meet the health needs of target populations. Their exact configuration varies from country to country. In some countries and jurisdictions, health care planning is distributed among market participants, whereas in others planning is made more centrally among governments or other coordinating bodies. In all cases, according to the World Health Organization (WHO), a well-functioning health care system requires a robust financing mechanism; a well-trained and adequately-paid workforce; reliable information on which to base decisions and policies; and well maintained facilities and logistics to deliver quality medicines and technologies.

Health care can form a significant part of a country's economy. In 2008, the health care industry consumed an average of 9.0 percent of the gross domestic product (GDP) across the most developed OECD countries. The United States (16.0%), France (11.2%), and Switzerland (10.7%) were the top three spenders.

Health care is conventionally regarded as an important determinant in promoting the general health and wellbeing of peoples around the world. An example of this is the worldwide eradication of smallpox in 1980—declared by the WHO as the first disease in human history to be completely eliminated by deliberate health care interventions.

Chapter 1. Computer System Overview

Chapter 1. Computer System Overview

Intruction Execution

A program to be execute by a processor consists of a set of instruction stored in memory. In its simplest form, instruction processing of two: the processor reads (fetches) intructions from memory one at a time and executes each instruction. Program execution consists of repeating the process of instruction fetch and instruction execution. The instruction execution may involve several opeartions and depend s on the nature of the instruction.

The processing requered for a single instruction is colled an instruction cycle. Using the simplified two-step description, the instruction cycle is depicted in Figure 1.2. the two steps are referred to as the fetch stage and the execute stage. Program execution halts only if the machine is turned off, some sort of unrecoverable error occurs, or a program instruction that halts the processor is encountered.


Figure 1.2. Basic Instructino Cycle

Instruction Computer

Instruction fetch: take instruction from program storage
Instruction decode: determining the required actions and instruction size
Operand fetch: get and put operand
Execute: Obtain and put operand
Result store: calculate the value of the outcome or status
Next instruction: determining the next instruction

The processor interprets the instruction and performs the required action. In general, these actions fall into your categories.

1. Processor memory : data may be transferred from processor to memory or from memory to processor.
2. Processor I/O : Data may be transferred to or from a peripheral device by transferring between the processor and an I/O module.
3. Data processing : the processor may perform some arithmetic or logic operation on data.
4. Control : An instruction may specify that the sequence of execution be altered.

Source :
William Stallings, “Operating Systems “Internals and Design Principles”, Fifth Edition, Pearson Education Internationl
Related Post :
Basic Elements
Processor Register
Intruction Execution
Interupts
The Memory Hierarchycal
Cace Memory
I/O Communication
Recommended Reading and Web Sites

Chapter 1. Computer System Overview

Chapter 1. Computer System Overview

Processor Register
A processor includes a set of register that provides a type of memory that is faster and smaller than main memory. The register in the processor serve two functions:
1. User Visible Registers
A user visible register may be referenced by means of the machine language that the processor executes and is generally available to all programs, including application programs as well as system program. Types of register that are typically available are data, address, and condition code registers.

Data Registers
Can be assigned to a variety of functions by the programmer. In come case, they are general purpose in nature and can be used with any machine instruction that performs operations on data. Often, however, there are restrictions. For example, there may be dedicated registers for floating-point operations and others for integer operations.

Address Registers
Contain main memory addresses of data and instructions, or they contain a partion of the address that is used in the calculation of the complete or effective address. These register may themselves be general purpose, or may be devoted to a particular way, or mode, of addressing memory. Examples include the following :

Index register
Index addressing is a common mode of addressing that involves adding an index to a base value to get the effective address.

Segment register
With semented addressing, memory is divided into segments, wicht are variable-length block of words.

Stack pointer
If there is user-visible stack addressing, then there is a dedicated register that points to the top of the stack.
2. Control and status register
A variety of processor registers are employed to control the operation of the processor. On most machines, most of these are not visible to the user. Some of the may be accesible by machine instructions executed in what is referred to as a control or operating system modes.

Of course,, different will have different register organizations and use different terminology. We provide here a reasonably complete list of register types, with a brief description.

1. Program Counter (PC) : Contains the address of the next to be fetched.
2. Instruction register (IR) : Contains the instruction most recently fetched.

Source :
William Stallings, “Operating Systems “Internals and Design Principles”, Fifth Edition, Pearson Education Internationl
Related Post :
Basic Elements
Processor Register
Intruction Execution
Interupts
The Memory Hierarchycal
Cace Memory
I/O Communication
Recommended Reading and Web Sites

Chapter 1. Computer System Overview

Chapter 1. Computer System Overview

An Operating system exploits the hardware resources of one or more processor to provide a set of services to system users. The operating system also manages secondary memory and I/O (input/output) devices on behalf of its users. Accordingly, it is important to have some understanding of the undelying computer system hardware we begin our examination of operating system.

Basic Elements

At top level, a computer consists of processor, memory, and I/O component with one or more modules of each type. These components are interconnected in some fashion to achieve the main function of the computer, which is to execute programs. Thus there are four main structural elements:

1. Processor : Controls the operating of the computer and performs its data processing function. When there is only one processor, it is often referred to as the central processing unit (CPU).
2. Main Memory: Stores data and programs. This memory is typically volatile; that is, when the computer is shut down, the contenst of the memory are lost. In contrast, the contents of disk memory are reatined even when the computer system is shutdown. Main memory is also referred to as real memory or primary memory.
3. I/O Moduls : Move data between the computer and its external environment. The external environtment consists of a variety of devices, including secondary memory devices, communications equipment, and terminals.
4. System bus L Provides for communication among processor, main memory, and I/O Modules.



Figure 1.1. Computer Components

One of the processor’s function is to exchange data with memory. For this purpose, it typically makes use of two internal (to the processor) register: a memory addres register (MAR(, whitch specifies the address in memory for the next read or write; and a memory buffer register (MBR), which contains the data to be written into memory or which receives the data read from memory. Similarly, an I/O address register (I/OAR) specifies a particular I/O device. An I/O buffer register (I/OBR) is used for the exchange of data between an I/O module and the Processor.

A memory module consists of a set of locations, defined by sequentially numbered addresses. Each location contains a bit pattern that can be interpreted as either an instruction or data. An I/O module transfers data from external devices to processor and memory, and vice versa. It contains internal buffers for temporrarily holding data until can be sent on.

Source :
William Stallings, “Operating Systems “Internals and Design Principles”, Fifth Edition, Pearson Education Internationl
Related Post :
Basic Elements
Processor Register
Intruction Execution
Interupts
The Memory Hierarchycal
Cace Memory
I/O Communication
Recommended Reading and Web Sites