Operating System Concepts

More About Airsoft Guns

2012-01-26T00:23:00.001-08:00

For the interested person who is looking to join the exciting and exhilarating fun of the sport of Airsoft, finding an affordable Airsoft gun is not as complicated as it may seem. Although some of the higher-end guns can be expensive, the average newcomer does not have to spend a small fortune to purchase and enjoy a quality Airsoft gun. Before the interested buyer begins to search for his optimal weapon, an understanding of the different types of guns that are available, and how these guns work can be very helpful.Generally speaking, Airsoft guns fall into three different categories, which are defined by how the guns are designed and operate. The more complicated the inner mechanisms that fire the guns, usually the more expensive they become.

The first category we will examine is the Automatic Electric Airsoft OR Airsoft AEG Gun or what is commonly referred to as the AEG. These electric guns are arguably the most popular guns among veteran Airsoft players. They have given the sport its greatest appeal and are singularly responsible for its explosive growth around the world. The AEG has an electric motor that is powered by an onboard battery. The motor turns the gears inside the gun, which in turn causes a piston to compress and release. The piston creates a blast of air that propels a 6mm plastic BB through the barrel of the gun. This fully automated system gives these guns the exciting rapid-fire feature that makes them so popular. These guns also tend to be the most expensive of the Airsoft gun family, usually costing around several hundred dollars.

The next group of guns to look at is the Gas Powered Airsoft guns. These guns operate by compressed air that fires the BB. The gas is either stored in an onboard cylinder or a gas filled magazine that connects to the gun. Some of the more popular styles are the gas blowback guns or commonly called the GBBs. The compressed air that fires the BB also returns the firing slide to the fire position at the same time. This return action creates a realistic ìrecoilî sensation from which the name blowback is derived. Reputed to be great fun to play with, the high-end GBB model guns can also cost around several hundred dollars. The non-blowback gas guns are less costly and start at around 40 dollars.

The last category of guns to look at is the Spring guns, which are also referred to as the ìSpringersî or Cheap Airsoft guns. Commonly tagged the cheap Airsoft gun, these spring guns were the original Airsoft models. In order for the gun to fire, a spring mechanism must be manually cocked back each and every time. Due to their simplistic design, the Springers are the most inexpensive and cost effective Airsoft guns. These guns are recommended as perhaps the best for entry-level players. Most players at some point have owned one of these models, which can be purchased for as little as 20 dollars.In an effort to find a cheap Airsoft gun the shopper must keep in mind the value for the money. Even though one can purchase a gun for around 20 dollars, this does not mean that the gun is cheap in quality. A well made 20 dollar Springer can be a great value for the money, just as a two hundred dollar AEG can be a great value as well. Usually no matter the price, buying a gun from a well-established Airsoft manufacturer like Zephyr Airsoft is important and worth the investment.

More on Paintballs

2012-01-14T05:49:00.000-08:00

This is a question asked by a majority of paintball players, as the first item that is usually changed on a paintball gun is the paintball barrel.With the huge number of selections available in the market, it is no surprise that players have a hard time choosing what paintball barrel to buy.Nowadays, the internet is used to search for what is hot, what works, what doesn’t work and which paintball barrel the top paintball teams use. Of course when people see their favorite teams playing, they love to check out all the equipment they are using and then proceed to purchase the exact same setup, with the paintball barrel.

Choosing the right paintball barrel is still very much a personal preference. Some believe that a longer barrel will be more accurate and some prefer a shorter barrel because they want to tuck into their bunkers and be more mobile.Then there are others who purchase paintball products including paintball barrels solely because of a certain brand. They don’t care about anything else.As more players become educated in choosing the correct paintball barrel for their marker and use, they will find that the experienced players always require a selection of different bore sizes so that they can “size” the paintball to have the best paintball to barrel match. Now this depends on what they wish to achieve. Some like to underbore and some like to overbore. What this means is that if the paintball size is a 0.689 then they might use a 0.693 so the fit is not too tight or they might use a 0.689 which would be a perfect fit.

Using a 0.693 in this case is overboring and players claim that it gives the paintball a chance to expand during its path down the barrel where a 0.689 might be perfect but if the paintball swells a little due to heat and humidity, it might break on its way out. Underboring here would be using a 0.685 bore size when the paintball is 0.689. Some players claim that due to the tight fit, the paintball will shoot a straighter path and be more accurate.All this is really personal preference and the best advice to anyone wishing to upgrade their paintball barrel, would be to test different kinds of barrels to see what feels best. A lot about choosing a paintball barrel is psychological.So, dont forget to check the Tippmann barrel , because this is the place where you can find all types of paint ball barrel guns.Let's face it, this is an expensive sport. Buying paintball supplies is definitely something we all want to do to save some cash. A hard day of playing can end up costing a lot of money if you have to buy high end or over priced paint.

A few weekends of playing can cost more than your equipment. What paintballs can you trust to deliver quality at a cheap price?Tippmann will be making some changes to their US ARMY paintball product line in the next month or so. They are replacing the standard US Army Alpha Black paintball gun with the new CARVER ONE. Tippmann will still be offering the Alpha Black in the Tactical model as well as the Tactical Egrip, Digital Camo Tactical and Project Salvo. This departure from the standard Alpha Black is likely due to the popularity of the Alpha Black Tactical over the standard Alpha Black which are offered at very close price points.

Paintball Game

2012-01-04T08:45:00.000-08:00

Recreational paintball games are fun, and the ideas you can come up with or participate in are many. For example a creative paintbal game that may be considered recreational paintball game is called President's Men. One person is the President (the president does not get a gun) and he or she has 4 or 5 special agents who have to protect him for a certain period of time dictated by the game.

Welcoming a wide variety of people, young and old, men and women, amateurs and pros, paintball has made a noticeable mark on the sports industry. The game of paintball holds a unique combination of many old games and sporting activities; From the skill and accuracy required in archery, to the thrill and adrenaline rush surrounding the many childhood games such as, tag, hide and seek, manhunt and so on.Where is the fun in paintball? Picture this…Your on the hunt, loaded paintball gun in hand. Suited in your uniform and googles, your ready for the battle that lies ahead of you.Looking across the way and see movement just behind a line of bushes.So you’d like to buy a paintball gun –what do you need to know? First, paintball guns are also called “markers.” The purpose for the term “marker” is based on the idea that the paintball gun is merely meant to mark a player, and the term “marker” sounds less violent.There are a few ways that you can start narrowing down the list of paintball guns that would be good for you.Price. First, you could narrow down the list of paintball guns that are right for you by price. For example, if you don’t want to spend over $200, your price limit would exclude a wide number of high-end paintball guns.

Let's face it, this is an expensive sport. Buying Cheap Paintballs is definitely something we all want to do to save some cash. A hard day of playing can end up costing a lot of money if you have to buy high end or over priced paint. A few weekends of playing can cost more than your equipment. What paintballs can you trust to deliver quality at a cheap price?

What are the most important things when it comes to the performance of your paintballs? Is the cheapest brand going to break in shipping? In your pods? Hopper? Barrel? Or will it not break at all, not even on your opponent? Let's take a look at what makes up some of the cheap paintballs that are commonly available from your favorite online store.If you shop at paintball store, you can get in their VIP program and get free shipping on a single case of paint. They also offer you cheaper prices on all of their paintball gear if you're a VIP member. That can save you a lot of money over time too.

Spending a little more on name brand cheap paintballs, like WPN Weapons Grade, is definitely our recommendation here. You need to think about how playing with white box or seconds paintballs is going to affect your game. If you can't shoot because of paintball failure, then it really isn't worth the couple of bucks you're going to save on that crap paint. Get cheap paintballs, but shop smart.

Cheap Car Hire Rates

2012-01-03T07:46:00.000-08:00

Looking for a hire car for business trips or holiday rentals, just one search with Cheap Car Hire Rates will enable you to compare prices of up to 50 companies and 28000 locations in seconds. Whether on holiday or business they provide you short term or long term contracts to suit you. There rental offers often include sat nav, air conditioning, free insurance, unlimited mileage, insurance waivers, additional drivers, free fuel, baby / child seats and a choice of automatic or manual drive. There suppliers offer a wide variety of vehicles such as sports hatchbacks, trucks, vans, people carriers, 7 seater, prestige models, mini buses, and family cars.

You can save time searching for your perfect car hire by using there independent price comparison website. The free price comparison offered here, provides you with an individual offer. You compare your hire car by price and quality. You can also filter your cheap car rental results according to your category, included services, extras or by preferred company. What follows is a detailed summary of your chosen car hire. Here, you will find from luxury car hire to cheapest car hire in only one click. You will see that you have found your hire car quickly, efficiently and conveniently.

If you are worried about the security of their website, then here I want you to tell you there website has been certified secured by VeriSign, which should assure you that we are a safe and legit option to book your hire car. There encoded ways of payment ensure a high level of security for our all users. Exclusive deals and conditions with car hire companies give you access to cheap car rentals and special deals when looking for your perfect car hire. There call centre will be there to help you throughout the entire process and we will of course stay your point of contact even after booking your hire car.

Alpinestars Shirts

2011-12-29T14:02:00.000-08:00

Get the latest Alpinestars clothing, t-shirts, caps & hoodies from Two Seasons, the UK's fastest growing board sports retailer. Alpinestars are one of the biggest auto and moto brands around so get involved if you're a fan!!!!

Alpinestars is the premier motocross company which have huge selections of casual apparels. From tShirts, shorts, hat, and many other sporty accessories. Luckily, you will find both comfortable and trendy look in Alpinestars T Shirts. Zephyrsports.com is the best place for you to find high quality sport clothing. One of the notable brands that offer you the best clothing is Alpinestars. This brand has a good reputation as one of the brands that offer the best sport apparels and gears. The most important aspect of what you wear is that you are comfortable in it.There are so many types of sport clothing provided in the online store so that you can easily find the best for you. And also, you will be able to choose your favourite design.

Online stores have become more and more competitive nowadays. Therefore many of them try to attract more customers by giving discounts and bonuses in their products. Visit this website, you will get best service, high quality t-shirts and fast delivery service. Zephyr Sports carries the complete line of Alpinestars apparel you need. There are many kinds and models of hoodies available on the market which comes from different brands, and alpinestars apparel are the favorite one.

The importance of special sport clothing to accompany your time during doing sport is highly regarded. Clothes that are intended for sports become part of a fashion trend. Considering the alpinestars shirts has become very popular nowadays. Other garments, which is also popular and is also a feeling of aura sporting a Alpinestars hoodie. It is very important to choose the best Skateboard Clothes to make your life smarter, better, faster and wiser. Logos are an important part of skateboard culture.

VmWare

2011-11-25T03:21:00.001-08:00

VMware is a popular commercial application that abstracts Intel 80X86 hardware into isolated virtual machines. VMware runs as an application on a host operating system such as Windows or Linux and allows this host system to concurrently run several different guest operating systems as independent virtual machines.Consider the following scenario: A developer has designed an application and would like to test it on Linux, FreeBSD, Windows NT, and Windows XP. One option is for her to obtain four different computers, each running a copy of one of these operating systems. Another alternative is for her first to install Linux on a computer system and test the application, then to install FreeBSD and test the application, and so forth. This option allows her to use the same physical computer but is time-consuming, since she must install a new operating system for each test. Such testing could be accomplished concurrently on the same physical computer using VMware. In this case, the programmer could test the application on a host operating system and on three guest operating systems with each system running as a separate virtual machine.The architecture of such a system is shown in Figure 2.16. In this scenario, Linux is running as the host operating system; FreeBSD, Windows NT, and Windows XP are running as guest operating systems. The virtualization layer is the heart of VMware, as it abstracts the physical hardware into isolated virtual machines running as guest operating systems. Each virtual machinehas its own virtual CPU, memory, disk drives, network interfaces, and so forth.

London Olympics

2011-09-27T06:51:00.000-07:00

As all we very well know about the last Olympics and its grand success that was held in China. In 2012 olympics are going to be held in London. People from all over the world had already started planning their leaves so that they can come to London and enjoy the grand Olympics here. Bookings had been already started in all the major hotels for these Olympics. If you are also planning for the London Olympics and want to be a part of it , then you have to also start planning for it. If you are worried about the accommodation and the food facilities at that time, then there are lot of places available in London that provides you ideal accommodation facility and self catering service.

Holiday Rentals is one of the place where you can find best London apartments on rental at a very affordable price. In addition to this they also provide you self catering facility where you can cook whatever you want,as per your taste. You have no need to depend on others like in major hotels where you are forced to have whatever is available at these hotels. Now a days these rental apartments are commonly known as Olympic Park Rentals as they are directly or indirectly linked to London Olympics.

Deadlock in Operating Systems

2011-08-27T04:40:00.001-07:00

A system consists of a finite number of resources to be distributed among a number of competing processes. The resources are partitioned into several types, each consisting of some number of identical instances. Memory space, CPU cycles, files, and I/O devices (such as printers and DVD drives) are examples of resource types. If a system has two CPUs, then the resource type CPU has two instances. Similarly, the resource type printer may have five instances.If a process requests an instance of a resource type, the allocation of any instance of the type will satisfy the request. If it will not, then the instances are not identical, and the resource type classes have not been defined properly.

For example, a system may have two printers. These two printers may be defined to be in the same resource class if no one cares which printer prints which output.
However, if one printer is on the ninth floor and the other is in the basement, then people on the ninth floor may not see both printers as equivalent, and separate resource classes may need to be defined for each printer.A process must request a resource before using it and must release the resource after using it. A process may request as many resources as it requires to carry out its designated task. Obviously, the number of resources requested may not exceed the total number of resources available in the system. In other words, a process cannot request three printers if the system has only two.

Class Path Vs Build Path

2011-08-12T08:29:00.000-07:00

This topic is liitle bit off to the operating system concepts but still I want to share it ;)

The classpath is the classic way to tell the Java compiler and the Java runtime where to find compiled classes. It is typically a sequence of JAR file names and directory names. The classpath used by the compiler and the runtime system don't have to be the same, but they typically "should be*, especially for a small project.

Buildpath is not classic Java terminology. It is the term for the richer way that a typical IDE specifies the relationship between the "modules" or "projects" that make up an application. The IDE uses this to figure out the classpath and sourcepath for compiling the Java code, and the classpath for running it. The IDE also uses the build path to figure out how to package up your code and its dependencies as (for example) a WAR file.

For example, an Eclipse build path for a project includes the other projects that it depends on, and lists any additional library JARs that the project contains / relies on. It also lists the packages in the current project that downstream projects can depend on.

(If you are using Maven for your project, the IDE buildpath mechanism is secondary to the dependencies declared in the POM files. For example, using Eclipse with the m2eclipse, the buildpath is synthesized from the POM files.)

Virtual Machines

2011-08-03T09:21:00.000-07:00

The fundamental idea behind a virtual machine is to abstract the hardware of a single computer (the CPU, memory,disk drives, network interface cards, and so forth) into several different execution environments, thereby creating the illusion that each separate execution environment is running its own private computer.By using CPU scheduling and virtual-memory techniques
), an operating system can create the illusion that a process has its own processor with its own (virtual) memory.

Normally, a process has additional features, such as system calls and a file system, that are not provided by the bare hardware. The virtual-machine approach does not provide any such additional functionality but rather provides an interface that is identical to the underlying bare hardware. Each process is provided with a (virtual) copy of the underlying computer. There are several reasons for creating a virtual machine, all of which are fundamentally related to being able to share the same hardware yet run several different execution environments (that is, different operating systems) concurrently.

Paging

2011-07-29T10:15:00.000-07:00

Hello friends in this post we are going to discuss on paging and how an operating system used it for memory management.

Paging is another memory management technique which widely uses virtual memory concept. When paging is used, the processor divides the linear address space into fixed-size pages (of 4KBytes, 2 MBytes, or 4 MBytes in length) that can be mapped into physical memory and/or disk storage. When a program (or task) references a logical address in memory, the processor translates the address into a linear address and then uses its paging mechanism to translate the linear address into a corresponding physical address.

Some physical memory is reserved for the operating system itself, and for its data structures. This is called wired memory, because it is not subject to paging. The rest of physical memory is managed via the paging mechanism, and is called the page pool. Whenever a virtual memory page that is not in physical memory is referenced, a page is allocated from the page pool’s free list and mapped to the required virtual memory address. Pages are returned to the free list when the memory has been unmapped or freed. Pages can be reclaimed from the free list if they are referenced again before the physical memory page has been reused.
OS performs an operation for storing and retrieving data from secondary storage devices for use in main memory. Paging is one of such memory management scheme. Data is retrieved from storage media by OS, in the same sized blocks called as pages. Paging allows the physical address space of the process to be non contiguous. The whole program had to fit into storage contiguously.

Paging is also used to deal with external fragmentation problem. This is to allow the logical address space of a process to be noncontiguous, which makes the process to be allocated physical memory.

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Round Robin Scheduling

2011-07-26T05:31:00.000-07:00

Round robin is the scheduling term which is being used for the purpose of algorithms which is mainly used for the purpose of operating systems. This system had mainly been used in order to handle out the processes which are incurred in the operating system which means that the time that is being taken for the opening of the program and then as a result the user is being shown with the process chart which is being drawn. The entire process is being done in equal portions where each and every item is being taken into account.

On the other hand a process schedule had been defined for the round robin scheduling system. This form is adopted in that case when the jobs or certain other tasks are to be performed. The round robin schedule is one of the easiest and simplest forms of doing the work and hence it can be carried out and implemented easily. The data is also being used in the round robin scheduling which means that in such a situation the user have to bear the data packet scheduling process. It had been found out that first come first serve basis is one of the alternative which can be used in the form of the round robin scheduling. This is one of that forms of scheduling which can be applied to other forms of scheduling as well and at time it is also used for the purpose of handling the problems too.

It is also used in the computation of the computer networks which is found to be quite helpful in the data packet scheduling process. The entire process of round robin scheduling generates about minimum and maximum of the results and it is referred to as the min-max fairness which means that each and everything is to be carried out on equal basis

All about Semaphores

2011-07-23T04:06:00.000-07:00

A semaphore is a synchronization mechanism that can be used to manage synchronization relationships and implement the access policies. A semaphore is a special kind of variable that can only be accessed by very specific operations. The semaphore is used to help threads and processes synchronize access to shared modifiable memory or manage access to a device or other resource. The semaphore is used as a key to access the resource. This key can only be owned by one process or thread at a time. Whichever task owns the key or semaphore locks the resource for its exclusive use.

Types:
Counting semaphores are used when you might have multiple devices (like 3 printers or multiple memory buffers).

Binary semaphores are used to gain exclusive access to a single resource (like the serial port, a non-reentrant library routine, or a hard disk drive). A counting semaphore that has a maximum value of 1 is equivalent to a binary semaphore (because the semaphore's value can only be 0 or 1.

Mutex semaphores are optimized for use in controlling mutually exclusive access to a resource. There are several implementations of this type of semaphore.

Implementation:
Semaphores can be implemented with a queue and an integer counter. You maintain the set of consumers in the queue, and when a consumer releases the semaphore, you retrieve the next entry in the queue and "wake" them to allow them to enter the critical section. When a consumer requests the semaphore, you simply push them onto the queue. If no one is in the critical section, you go ahead and grant the requester the right to enter the critical section.

Real Time Operating System

2011-07-21T04:59:00.000-07:00

A real time operating system is based on the OS which has the capability to perform a number of functions at a time. This RTOS only serves real-time applications. These real-time applications include robots, spaceships; research tools used by scientists and embedded systems like home appliances, cell phones and thermostat.

RTOS system captures the real time events and brings out the results which may slightly differ from the reality. It’s processing and computation totally depends on the way it is programmed. RTOS can be judged as how quickly it performs the operation and how accurate the results are. Most important factors which increase the working of this system are low interrupt latency and a low thread switching latency.

The real time operating system is designed keeping in mind every aspect in mind of real life. This operating system is designed on two basic principles. First design pattern is that it should focus on event-driven programming so that tasks can process depending upon their scheduling priorities. Second design refers to time sharing feature so to process tasks on the basis of clock interrupts.

In RTOS allocation of memory is the most critical task. Two elements are of significant importance in case of memory allocation. First one is speed and second is the fragmentation of free region during the memory allocation process.

Golf terms

2011-07-19T12:05:00.000-07:00

Golf is now the emerging game that is popularized among all the people. Earlier only the rich and educated people played it. Now the popularity of the game is wide spread, so that every one has interest in playing the game. This particular game attracts all the types of crowds regardless of their age. Many people are now interested in learning this game. Mainly students involve themselves in this game so much and are very eager to learn the game. They are interested in learning in all the nuances, rules and regulations of the game. Since many people are interested in learning the game, there are many golf academies newly erecting in and around the city. Golf academies bear the responsibility to teach the young generation about the game. The rules of the golf etiquette are the first and fore most things, the golf academies teach their students. The rules of the game mainly aim at the safety of the golfers and to the pace of the play, which helps in keeping the game enjoyable. The golf etiquette is an essential part of the game. This is something very vital that all the new comers and the new beginners should learn on the course. For any game to be played successfully, the instruments used for the play shohttp://www.blogger.com/img/blank.gifuld be manufactured or prepared with utmost care and you can found all these instruments at their Golf shop. A standard set of a golf club mainly consists of three woods, eight irons and a putter. Actually according to the rules and regulations of the play a golfer is allowed to carry 14 clubs in the bag. The more clubs the player carries the easier is his victory. To know more about golf academies, please visit Golfreisen.
The above site explains you all the details about the game. They are one of the largest German golf shops with a full range of all brand names. You can also visit Golfkurse it will be useful for you.

Golf Platzreife means "Complete and utter load of bollocks" in English and I will tell you why.

The idea behind it is that you answer a few questions about golf rules and then play a few holes of golf with your instructor. As long as you do not kill too many people whilst playing then you get your 54 handicap... Seriously.. 54 handicap. Basically a 54 handicap means you cannot actually play golf at all and should not really be allowed on a half-decent golf course... But everybody must start somewhere I suppose.....

Demand Paging

2011-07-18T12:38:00.001-07:00

Virtual memory can be implemented by a technique called demanding paging. It is a technique in which a Page is brought into memory when it is actually needed.
A typical life cycle of a process is as follows:

1. When a process is initiated, the operating system must at least load one page in real memory. It is the page containing the execution part of the process.
2. Execution of the process commences and proceeds through subsequent instructions beyond the starting point.

3. This execution continues as long as memory references generated by this page are also within same page. The virtual address created may reference a page that is not in real memory. This is called a page fault. It generates an interrupt that asks for the referenced page to be loaded. This is called demanding page.

4. The operating system will try to load the referenced page into a free real memory frame. When this is achieved the execution can continue.
5. Finally when the process terminates, the operating system releases all the pages belonging to the process. The pages become available to other processes.
In general, the operating system accommodates the new page by removing a currently loaded page that is not in use. This is called page replacement. It is important to remove a page that will not be accessed in a short time. It will reduce the number of page faults in the system.

Ideal Place for Golf Club House

2011-07-14T22:11:00.000-07:00

As in my previous posts i already discussed about the golf,rules,its history and etc.
Yesterday I was visiting some golf club house locations and in those the one that i really found interesting is Whisper Rock Golf Course Homes.They provides you such a wonderful location in Scottsdale area that is ideal for any golf course home.

The whisper rock golf club scottsdale attempts to demonstrate that a conventional commercial building system can be transfigured into a design solution that recalls a traditional lineage, that of the traditions of the game of golf, while simultaneously transcending traditional responses by commenting on the present. When the owner and originator of the golf facilities first asked us to take part in the design competition for the club I was hesitant, not being a golfer or knowing much about golf. His response was simply “its not just about golf, its about people and space!” As the finished clubhouse comes alive each day with activity and the passing of time, I am reminded that no matter the building type, scope, or size, in the words of Rudolf Schindler, “the perception of architecture is not in the eyes, but in the living.”

If you have any doubt or queries regarding buying or selling the club house in the space you can always contact to Holm Group that will help you in exploring more.

Multiprocessor thread scheduling strategies

2011-07-14T10:06:00.000-07:00

Load Sharing: Processes are not assigned to a particular processor. A global queue of threads is maintained. Each processor, when idle, selects a thread from this queue. Note that load balancing refers to a scheme where work is allocated to processors on a more permanent basis.

Gang Scheduling: A set of related threads is scheduled to run on a set of processors at the same time, on a 1-to-1 basis. Closely related threads / processes may be scheduled this way to reduce synchronization blocking, and minimize process switching. Group scheduling predated this strategy.

Dedicated processor assignment: Provides implicit scheduling defined by assignment of threads to processors. For the duration of program execution, each program is allocated a set of processors equal in number to the number of threads in the program. Processors are chosen from the available pool.

Dynamic scheduling: The number of thread in a program can be altered during the course of execution.

Short,Medium and Long term scheduler

2011-07-13T06:16:00.000-07:00

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 part of the swapping function. This relates to processes that are in a blocked or suspended state. They are swapped out of real-memory until they are ready to execute. The swapping-in decision is based on memory-management criteria.

Short term scheduler, also know as a dispatcher executes most frequently, and makes the finest-grained decision of which process should execute next. This scheduler is invoked whenever an event occurs. It may lead to interruption of one process by preemption.

OS-9

2011-07-12T02:27:00.000-07:00

I was trying to write this post from last 2 years, but always i postponed it.Now I have decided to done it.This post is about an operating system OS-9 from legacy systems developed by Microware.OS-9 is a real-time, multiuser, multitasking operating system developed by Microware Systems Corporation. It provides synchronization and mutual exclusion primitives in the form of signals, events, and semaphores. It also allows communication between processes in the form of named and unnamed pipes, as well as shared memory in the form of data modules.

OS-9 is modular, allowing new devices to be added to the system simply by writing new device drivers, or if a similar device already exists, by simply creating a new device descriptor. All I/O devices can be treated as files, which unifies the I/O system. In addition, the kernel and all user programs are ROMable. Thus, OS-9 can run on any supported hardware platform from simple diskless embedded control systems to large multiuser minicomputers.

Originally developed for the 6809 microprocessor, OS-9 was a joint effort between Microware and Motorola. The original version of OS-9 (OS-9 Level I) was capable of addressing 64 kilobytes of memory. OS-9 Level II took advantage of dynamic address translation hardware, and allowed a mapped address space of one megabyte on most systems, and up to two megabytes on others, most notably the Tandy Color Computer 3.

In the 1980's, Microware ported OS-9 to the 68000 family of microprocessors, creating OS-9/68000, which is used in a variety of industrial and commercial arenas, including Philips' CD-i and most recently, set-top boxes for interactive television.

Error in Loading Operating System

2011-07-11T06:51:00.000-07:00

The Error Loading Operating System error appears when your operating system fails to load properly. This error is localized to the Microsoft Windows XP operating system, so users of other operating systems should not face this problem. Essentially, the Error Loading Operating System occurs at a point between the computer’s BIOS running checks on the system’s hardware and the actual launching of the operating system. This error is usually accompanied by a black screen and occurs directly after the installation of Windows XP.

What causes this error?
You can expect to see the Error Loading Operating System error when there is an issue with the way the BIOS and the Windows XP operating system are communicating with each other. Most commonly, the BIOS has an issue where it does not support or has no way to correctly manage the capacity of the hard drive that Windows XP was installed to.

How can I resolve this error?
The Error Loading Operating System problem can be solved in a variety of different ways. However, it is important that you have some knowledge of computers before you proceed with any of the suggested solutions to this error message. Not knowing exactly what you are doing, or failing to follow the directions you see on your screen could result in the corruption or destruction of your computer. Changing or flashing your BIOS can have detrimental effects on your computer and should only be performed if you are completely sure you know what you are getting into.

Your first step to resolve the Error Loading Operating System issue should be to update your computer’s BIOS. Check your computer’s manual for information on how to do this or call the company which constructed your computer. Alternatively, if you built your computer yourself, consult the manual which came with your motherboard.

Once you are sure that your BIOS has been upgraded to its most recent version, determine which type of BIOS you are using. Each BIOS is somewhat different, and newer versions of popular BIOSes tend to change the locations of different functions and features, so consult your computer vendor, your motherboard manual, or a tech support forum for the most up to date information on how to make sure that your hard drives are interfacing properly with your BIOS.

My true companion Ticket America

2010-12-31T09:36:00.000-08:00

If you are an american then you are definitely aware of what exactly ticket america is because it is the only site that made a tremendous growth in last few years in providing best services to its users in the field of entertainment. If you want to know what latest is happening in your town then you can simply visit their site and get to know about all the facilities that they provide in the form of concerts,city guides,sports or any other useful information that you need for your entertainment. In this post I am mainly going to concentrate on all the stadiums where you can get the tickets from here.The biggest point for Ticketamerica is that they are far from unique in applying these extra costs, and it is symptomatic of the ticketing industry in general, rather than this one individual supplier. With ticket america can get a chance to visit all the best stadiums across whole america which includes Bank of America Stadium,Lucas Oil Stadium,Lambeau Field,FedEx Field,Invesco Field and may more in the same list.

Assuming there are tickets remaining to your show, the tickets you have selected will be presented to you. Once they are in your 'basket', you have a limited amount of time to complete the transaction before the tickets are released for other people to buy. This is normally a few minutes worth, but it's often best to have all of your card details at hand to avoid any wasted time. Another alternative is to create an account on the site, whereby all of your personal information is stored, thus making the checkout process a lot quicker.

Review on Ticket America 4

2010-11-27T03:53:00.000-08:00

If you are a real fun loving person and fond of visiting different different stadiums and even not getting chance to look on all these then here is a place for you where you can complete any of your game dream. Now here is a great news for american people because with Ticket america you can get a chance see matches in all those stadiums and enjoy matches their. But sometimes it is very difficult to get these tickets because a lot of people want to see the same matches in all those lovely stadiums like Bank of America Stadium,Lucas Oil Stadium,Lambeau Field,FedEx Field,Invesco Field and many more in the same list.

Here I am going to give you some more detail about Yankee Stadium,in Yankee stadium their are two sections at Yankee Stadium that offer fans with a more economical way to see a game, The Tier Reserved outfield and the Bleachers. The Tier Reserved outfield consists of sections 26-36 and 25-35. These sections are nosebleed seats and they are far down the line, but they get you into the park at a cheap price. The Bleacher sections are better in that they are not elevated as high but as with many bleacher sections in most MLB parks a birds eye view is hard to come by. Bleacher sections are numbered as 37 to 59. If your fortunate enough to sit in the lower rows of the Bleachers, you will be able to get a nice view of the bullpens. Again, these two sections get you in and allow you to indulge in few extra brews.

Review on Ticket America 3

2010-11-05T02:05:00.000-07:00

If you plan to attend any kind of ticketed event on your travels to the USA, then I can give a big thumbs up to Ticketmaster.com, the biggest provider around, and in my experience, also the best. I've used this service several times when attending sporting events in the USA, and it works quite smoothly, so I have no real complaints at all about the service. The biggest negative for Ticketmaster is their hefty service and transaction charges that are applied to each order, but they are far from unique in applying these extra costs, and it is symptomatic of the ticketing industry in general, rather than this one individual supplier. You can book the tickets for any of your favorite matches,it may be kentucky basket ball match tickets,george town hoyas basket ball group, tennessee vols mens basketball group or kansas state wildcats mens basketball match.

Assuming there are tickets remaining to your show, the tickets you have selected will be presented to you. Once they are in your 'basket', you have a limited amount of time to complete the transaction before the tickets are released for other people to buy. This is normally a few minutes worth, but it's often best to have all of your card details at hand to avoid any wasted time. Another alternative is to create an account on the site, whereby all of your personal information is stored, thus making the checkout process a lot quicker.

Review on Ticket America 2

2010-10-15T06:17:00.000-07:00

If you enjoy going to see live music then you should check out TicketAmerica.com. They have a huge list of arenas and stadiums all over the country. For example, they offer tickets to events at Green Bay Packers,Philadelphia,New York Yankees,Detroit Lions,San Fransisco Giants, Arco Arena, Chicago Bears,Staples Center, Texas rangers,Carolina Panthers and many, many others.

The website is easy to navigate and contains all of the information you need to choose the perfect seat and area. They also have phone numbers, layouts and maps. The maps open up into a Google Map page so you can see the entire area (in case you need driving directions or just want to see if there's a restaurant or hotel nearby.)

They're touted as having the most comprehensive inventory of tickets online, and tickets are sent via FedEx. Some of the current list of shows are Kelly Clarkson, John Mayer, Leonard Cohen, No Doubt, and Neil Diamond (yes, he's still performing!) There are many, many other tickets available for other shows as well. And you can order from the comfort of your own home.

Review on Ticket Amercia

2010-10-15T06:08:00.000-07:00

If you enjoy going to see live music then you should check out TicketAmerica.com. They have a huge list of arenas and stadiums all over the country. For example, they offer tickets to events at Philadelphia, New York Yankees,San Fransisco Giants, Arco Arena, Staples Center, Texas rangers, and many, many others.

The website is easy to navigate and contains all of the information you need to choose the perfect seat and area. They also have phone numbers, layouts and maps. The maps open up into a Google Map page so you can see the entire area (in case you need driving directions or just want to see if there's a restaurant or hotel nearby.)

They're touted as having the most comprehensive inventory of tickets online, and tickets are sent via FedEx. Some of the current list of shows are Kelly Clarkson, John Mayer, Leonard Cohen, No Doubt, and Neil Diamond (yes, he's still performing!) There are many, many other tickets available for other shows as well. And you can order from the comfort of your own home.

Get rid of aging problem

2010-06-24T10:50:00.000-07:00

Antioxidants are intimately involved in the prevention of cellular damage -- the common pathway for cancer, aging, and a variety of diseases. The scientific community has begun to unveil some of the mysteries surrounding this topic, and the media has begun whetting our thirst for knowledge. Athletes have a keen interest because of health concerns and the prospect of enhanced performance and/or recovery from exercise. The purpose of this article is to serve as a beginners guide to what antioxidants are and to briefly review their role in exercise and general health. What follows is only the tip of the iceberg in this dynamic and interesting subject.

Endurance exercise can increase oxygen utilization from 10 to 20 times over the resting state. This greatly increases the generation of free radicals, prompting concern about enhanced damage to muscles and other tissues. The question that arises is, how effectively can athletes defend against the increased free radicals resulting from exercise? Do athletes need to take extra antioxidants?

Because it is not possible to directly measure free radicals in the body, scientists have approached this question by measuring the by-products that result from free radical reactions. If the generation of free radicals exceeds the antioxidant defenses then one would expect to see more of these by-products. These measurements have been performed in athletes under a variety of conditions.

Glutathione (gamma-glutamyl-cysteinyl-glycine; GSH) is the most abundant low-molecular-weight thiol, and GSH/glutathione disulfide is the major redox couple in animal cells. The synthesis of GSH from glutamate, cysteine, and glycine is catalyzed sequentially by two cytosolic enzymes, gamma-glutamylcysteine synthetase and GSH synthetase. Compelling evidence shows that GSH synthesis is regulated primarily by gamma-glutamylcysteine synthetase activity, cysteine availability, and GSH feedback inhibition. Animal and human studies demonstrate that adequate protein nutrition is crucial for the maintenance of GSH homeostasis. In addition, enteral or parenteral cystine, methionine, N-acetyl-cysteine, and L-2-oxothiazolidine-4-carboxylate are effective precursors of cysteine for tissue GSH synthesis.

These initial products position OXIS for a feasible entry into the wellness market with a lot of room for expansion. This paves the way for solid partnerships with leaders in the industry with an established customer base or those with the capacity to build one. The ultimate goal is to be regarded as a health partner. For now, it may be penny stocks for OXIS, but with more nutraceutical products lined up (including functional foods like nutrition bars and energy beverages sold over the Internet and through multi-level marketing, infomercials, direct mail, and retail outlets), the future of OXIS is secure and will benefit people all over, allowing them to be healthy and young.

http://www.oxis.com

Oxis on Twitter

Oxis on facebook

Firmware

2010-06-17T05:46:00.000-07:00

Fixed software programs that internally control various electronic devices or individual hardware parts of these devices (such as mobile phones). They involved very basic low-level operations of the device, without which the device would be completely non-functional.More simple firmwares are usually stored on ROM or OTP/PROM, while more complex firmwares occupy flash memory to allow for updates. Common reasons for updating firmware include fixing bugs or adding features to the device.Doing so usually involves loading a binary image file provided by the manufacturer into the device, according to a specific procedure. More often than not this is meant to be done by the end user.

FM Radio??? A big question for me.....

2010-05-14T07:14:00.000-07:00

The built-in FM radio tuner is now considered a basic feature. It allows the user to listen to most of the live-broadcasted FM radio stations. Almost all phones with FM radio tuner require a wired headset to be connected to the unit as it’s used as an antenna.Most FM radio tuners can receive basic radio station info over RDS. The use of FM radio does not interfere with the network carrier and it’s free.Nokia enhance their FM radio interfaces with the Visual Radio enhancement that adds visuals and text as an additional info layer to normal radio broadcasts.A presentation of graphics and text, synchronized to the audio programming, gets downloaded to the phone over a data connection; the FM transmission chain is unaffected by the addition of Visual Radio.

Here's the type of content that Visual Radio can offer:

* Information on the song and artist currently playing on air
* View images related to presenters or news stories
* A weather map during the weather broadcast
* News, weather and traffic alerts while songs are playing
* Listen in to a talk show and see what has been discussed so far
* Join in audience votes, Big Brother style
* Participate in on-air competitions

Cluster Computing

2010-04-27T06:17:00.000-07:00

In computers, clustering is the use of multiple computers, typically PCs or UNIX workstations, multiple storage devices, and redundant interconnections, to form what appears to users as a single highly available system. Cluster computing can be used for load balancing as well as for high availability. Advocates of clustering suggest that the approach can help an enterprise achieve 99.999 availability in some cases. One of the main ideas of cluster computing is that, to the outside world, the cluster appears to be a single system.

A common use of cluster computing is to load balance traffic on high-traffic Web sites. A Web page request is sent to a "manager" server, which then determines which of several identical or very similar Web servers to forward the request to for handling. Having a Web farm (as such a configuration is sometimes called) allows traffic to be handled more quickly.Clustering has been available since the 1980s when it was used in DEC's VMS systems. IBM's sysplex is a cluster approach for a mainframe system. Microsoft, Sun Microsystems, and other leading hardware and software companies offer clustering packages that are said to offer scalability as well as availability. As traffic or availability assurance increases, all or some parts of the cluster can be increased in size or number.

Understand what daemon is???

2010-04-13T07:10:00.000-07:00

A demon (also see daemon which has a somewhat similar meaning) is a program or process, part of a larger program or process, that is dormant until a certain condition occurs and then is initiated to do its processing. Eric Raymond cites an artificial intelligence ( artificial intelligence ) application as an example. An AI program might include a number of demons, one or more of which might become active when a new piece of knowledge was acquired by the AI program. If the new knowledge affected a particular demon's own sphere of knowledge, it would spring into action and create new pieces of knowledge based on its particular inference rules. Each of these new pieces of knowledge might in turn activate additional demons that would continue to filter through and refine the entire AI knowledge base.

Understand what are .ini files

2010-04-07T06:42:00.000-07:00

INI is a file name extension used in Microsoft Windows. The letters stand for initialization. As this term implies, INI files are used to initialize, or set parameters for, the operating system and certain programs.

In Windows, two common INI files are SYSTEM.INI and WIN.INI. It is possible to get some idea of what these files do by opening them in a plain-text (ASCII) word processor or in a DOS editor. The files contain statements that set various parameters for the mouse, keyboard, peripherals, screen colors, passwords, and so on. Under ordinary circumstances, no changes should be made to these files in the text editor. (If the text editor presents the option to "Save changes" upon closing, click on "No.")

In Windows 95, 98, NT, and later versions, much of the configuration is done through values in the registry, rather than through INI files. Certain programs contain their own INI files. The contents of these files are normally modified by changing the characteristics of a program through the user interface for that program, not by editing the files themselves.

Difference between Table and View in Oracle

2010-04-05T04:56:00.000-07:00

A table is where you store your data. The table actually occupies space on disk. A sample table might be the EMPLOYEE table which has the columns EMPID, EMP_NAME, and SALARY.

A view is a stored query. A sample view might look like the following:

CREATE VIEW emp_view AS SELECT empid,emp_name FROM employee;

Notice that in the view, I have omitted the SALARY column. You can then query the view similar to the following:

SELECT * FROM emp_view;

Oracle will know this is a view and automatically rewrite the query to return only the EMPID and EMP_NAME columns from the EMPLOYEE table.

Views are used primarily to store a common query in the database. Without the view, you might have the same complex query stored in multiple locations in your application code. If you need to make a change, you would have to change the query in all locations. However, if that query were in a view, you would only have to change it in one location.

The other common reason for a view is for security purposes. If I grant a user the ability to query EMP_VIEW and they do not have permissions to query the EMPLOYEE table, then they could never see the SALARY column.

Understand Deadlock

2010-04-01T07:10:00.000-07:00

A deadlock is a situation in which two computer programs sharing the same resource are effectively preventing each other from accessing the resource, resulting in both programs ceasing to function.

The earliest computer operating systems ran only one program at a time. All of the resources of the system were available to this one program. Later, operating systems ran multiple programs at once, interleaving them. Programs were required to specify in advance what resources they needed so that they could avoid conflicts with other programs running at the same time. Eventually some operating systems offered dynamic allocation of resources. Programs could request further allocations of resources after they had begun running. This led to the problem of the deadlock. Here is the simplest example:

Program 1 requests resource A and receives it.
Program 2 requests resource B and receives it.
Program 1 requests resource B and is queued up, pending the release of B.
Program 2 requests resource A and is queued up, pending the release of A.

Now neither program can proceed until the other program releases a resource. The operating system cannot know what action to take. At this point the only alternative is to abort (stop) one of the programs.

Learning to deal with deadlocks had a major impact on the development of operating systems and the structure of databases. Data was structured and the order of requests was constrained in order to avoid creating deadlocks.

Below is a funny example of car deadlock.
:)

What is Cygwin

2010-03-31T06:15:00.000-07:00

Cygwin is an open source collection of tools that allows Unix or Linux applications to be compiled and run on a Windows operating system from within a Linux-like interface. This capability helps developers to migrate applications from Unix or Linux to Windows-based systems, and makes it easier to support their applications running on the Windows platform. Cygwin includes a dynamic link library (DLL) and a collection of tools. The DLL serves as a Linux emulator, and the tool set provides the Linux-like development environment.

Using Cygwin, developers can more easily provide remote support for applications running on Windows platforms. Because Unix and Linux are open to public input, administrators have contributed a great number of management scripts for these systems over the years, helping to assemble a large collection of available administrative tools. Cygwin makes it possible to use these scripts on computers running Windows, as well. An administrator can log in to a Windows-based computer and fix user problems within a Unix or Linux shell, and can also incorporate Windows command line interface tools into the shell script environment.

The name Cygwin was created from a combination of Cygnus and Windows

Know more about Cron Script

2010-03-31T06:09:00.000-07:00

A CRON script is a list of one or more commands to a computer operating system or application server that are to be executed at a specified time. Each command is executed when its triggering time arrives. In Unix-based operating systems, the crontab command is a user interface command that creates or changes a file (called a crontab file). This file contains a list of UNIX shell commands, each with a specified time of execution. A CRON script is similar.

Oracle revenue up

2010-03-26T07:39:00.000-07:00

Fueled by growth in new software licenses, Oracle revenue for its fiscal third quarter, ended Feb. 28, increased 17% from the same period last year, hitting $6.4 billion, though earnings declined due in part to restructuring charges incurred by the company's purchase of Sun Microsystems.Oracle reported third-quarter earnings of $1.2 billion, a drop of 10% compared to the same period last year.

Excluding special charges, earnings per share grew 9% to $1.9 billion or $0.38 per share, with $6.5 billion in revenue. Analysts polled by Thomson Reuters had on average predicted earnings per share of $0.38 and $6.35 billion in revenue.
New software license revenues, which are considered a key indicator of growth and market temperament, grew 13% to $1.7 billion.Software license updates and product support revenue continued to be key for Oracle's performance, rising 13% to $3.3 billion, or just over half of all revenue.

Total hardware systems revenue was $458 million, but the figure does not represent a full quarter, as the Sun deal closed in January.Oracle's work on integrating Sun is going well, and Sun products will make "a significant contribution" to Oracle's fourth-quarter earnings, co-President Safra Catz said in a statement.

Oracle's Exadata data warehousing machine is "the fastest-growing product" in company history, with nearly $400 million in the sales pipeline, co-President Charles Phillips said in a separate statement.It's become a tradition for Oracle executives to bash applications rival SAP during earnings calls, but Thursday's call featured an especially large dose of trash talk.

CEO Larry Ellison bashed SAP's technology, particularly its ABAP programming language. Oracle's Java-based Fusion Applications -- set for release in the second half of this year after a long delay -- will give his company a major edge, Ellison said.Fusion Applications will be sold as on-premises software, integrated appliances, and in on-demand form.

"We're going to go compete with SAP's 25-year-old technology. Once we deliver Fusion, we're going to be well-positioned to challenge for the number-one slot [in applications]," Ellison said.He neglected to mention that SAP developers nowadays also have the option to program in Java.Ellison acknowledged that Fusion Applications have been a long time coming but said it was for the best.

"We did not make the mistake of trying to rush this out early. Were we late with Fusion? Yes, we were late." But that is preferable to releasing a poor product, he said.With the Sun deal complete, Oracle's broader strategy involves selling customers integrated systems spanning hardware, storage, middleware and applications.

To this end, "there will be other clusters like Exadata ... coming out pretty much for all of the software we sell," Ellison said.

Oracle partnered with Hewlett-Packard on the original Exadata machine, but jumped to Sun technology for the second version, which is aimed at transaction processing as well as data warehousing.Oracle wants to compete with IBM's "biggest, best box," Ellison said. "We're going to get better and better at large-scale transaction processing."

Review on Addiction Treatment

2010-01-05T14:33:00.000-08:00

Entering Addiction treatment to try to get my alcohol and cocaine abuse under control I thought that my only problem was substance abuse. It wasn’t long into my addiction treatment that I learned that the reason why I had been abusing substances since my teenage years was to avoid dealing with the death of my brother. The treatment facility quickly recognized this and put together a treatment plan for me that would help me mourn my brothers passing as well as address my addiction. The staff at the addiction recovery program provided me with support and understanding. I did not feel like I was “less then” because of my dependency to drugs and alcohol.

As my drug treatment experience went on I could literally feel myself changing. For the first time I was able to talk about my brother and more importantly cry without having to put drugs or alcohol into my body to self medicate. I was learning that it was okay to feel sad and vulnerable. I also started to feel remorse for all of the emotional harm that I caused my family and friends during my active addiction. I never realized that I was not only just hurting myself but everyone that cared about me. During my drug addiction I was not capable of helping, caring, or loving others. How could I? I didn’t know how to love and respect myself.

Addiction treatment got my recovery off on the right foot. It built the foundation for a long lasting recovery contingent that I continue to take suggestions. If it wasn’t for my drug abuse and addiction treatment I don’t think that I would be becoming the man I am today. Someone that I can look in the mirror at an be happy with. Now I am able to treat people with care and understanding and not make selfish decisions that will only benefit my cause.

The need to find a drug rehab program in Florida that treats dual diagnosis is an important step in stopping the destructive lifestyle of drug abuse and addiction. Drug abuse and addiction not only affects the addict but also the family, friends, co-workers and loved ones who are intimately connected with him or her.

Follow your own fashion style

2009-12-03T07:44:00.000-08:00

I was watching the fashion show episode of Gossip Girl and remembered how much I love this show. It’s so smart despite its over use of sexed up teenagers. Eleanor Waldorf said to Jenny after her green mess of a dress goes down the runway she is going to expose her “Eve Harrington ways.” Now, I doubt the average GG viewer would even pick that up, and I sure didn’t the first time. But it’s a reference to the classic film “All About Eve” starring Bette Davis as an aging actress who is usurped by a younger manipulative Eve.So with a renewed appreciation for GG, I remember the great fashion moments and trend sparked by the Upper East Siders this year. The female stars also made a splash on the red carpet, with Leighton Meester amping up the stakes with her edgy, innovative looks.

It has been bitterly cold down south this winter. Seriously, I feel as if I have been freezing my tail off. This hasn’t left me with a lot of fashion inspiration. Most of what has inspired me is a nod to warmer days.The shoes are the cutest things Target has carried in a while so i mostly prefer ugz boots. Target got really dull with their shoes, so these bright and sparkly ones are just what the doctor ordered. The bags, on the other hand, are cute but completely disconnected from the shoes.

I’ve just finished reading this book by Anna Davis, and it’s a must read for every fashion-crazed woman with a penchant for SHOES! The book is set in the roaring 1920s Paris, and the heroine is aspiring poet Genevieve who has found herself in a loveless marriage.She is a shoe- and fashion-obsessed member of the aristocratic class. Instead of publishing her own writings, she gets her wealthy American husband to back her Bohemian friends’ enterprises. She sees one of her rivals wearing a pair of some of the most unattainable shoes in the world and decides she must have them.

Know more about golf

2009-08-22T06:13:00.000-07:00

Golf is now the emerging game that is popularized among all the people. Earlier only the rich and educated people played it. Now the popularity of the game is wide spread, so that every one has interest in playing the game. This particular game attracts all the types of crowds regardless of their age. Many people are now interested in learning this game. Mainly students involve themselves in this game so much and are very eager to learn the game. They are interested in learning in all the nuances, rules and regulations of the game. Since many people are interested in learning the game, there are many golf academies newly erecting in and around the city. Golf academies bear the responsibility to teach the young generation about the game. The rules of the golf etiquette are the first and fore most things, the golf academies teach their students. The rules of the game mainly aim at the safety of the golfers and to the pace of the play, which helps in keeping the game enjoyable. The golf etiquette is an essential part of the game. This is something very vital that all the new comers and the new beginners should learn on the course. For any game to be played successfully, the instruments used for the play should be manufactured or prepared with utmost care and you can found all these instruments at their Golfshop. A standard set of a golf club mainly consists of three woods, eight irons and a putter. Actually according to the rules and regulations of the play a golfer is allowed to carry 14 clubs in the bag. The more clubs the player carries the easier is his victory. To know more about golf academies, please visit Golfreisen.
The above site explains you all the details about the game. They are one of the largest German golf shops with a full range of all brand names. You can also visit golfkurse it will be useful for you.

Concept of Process

2009-05-31T05:01:00.000-07:00

In simple terms we can say that a process is a program in execution. A process is not only the program code which is known as text section. A process can also include the program activities which are represented by the program counter and processor’s registers. A process also includes a stack that contains the temporary data like function parameters,return addresses and local variables and a data section that contains the global variables.A process also contains a heap which is the memory that is allocated dynamically to the process during its creation and execution.

Here,one thing that you had to make very much clear in your mind is that a process can never be a program because a program is a passive entity and a process is an active entity. A program becomes a process when it is loaded into memory.The most common technique that is used for loading a program into main memory is by double clicking on that icon or you can type the name of that program on the command line.It is possible that two or more than two processes are associated with a program but this does not mean that they are different execution sequences.For instance,several users may running different copies of the same email program, or the same user may invoke different instances of the web browser.Each of these is a separate process and although the text sections are equivalent while the stack and heap sections may vary.

Get rid of your financial crisis

2009-05-28T04:44:00.000-07:00

Ezunsecured.com is a premier organization that helps in making the life of many people, those are very deeply affected by recession and in great need of some financial aid.This organization provides its various types of loans schemes to its clients so that you can select any of them as per your requirement.Their personal loans scheme are very easy and attractive and anyone can easily take benefit from them.For availing all these facilities you had to just signup with them,and once you sign up you will be eligible for their ultimate personal financing service.Here,they provide you personal loan of $ 400,000 without any documentation,if you are in need of much larger amount then also you can contact them.

They also provides personal loan of up to $ 10 million with easy documentation facility.If you are worried about unsecured personal loans then here I want to tell you this company experiencing very high approval rates for the first $100,000 of Unsecured Financing even in this market.Their terms and conditions are so easy that you can easily take advantage of them.If you want more proof on how this company helped other people in recovering their business then you can watch the success stories of the people that already taken benefit from them.

Best Marble Shop

2009-05-24T10:16:00.000-07:00

If you are worried about the designing and installation of your kitchen and bathroom then marblecityca.com is the right place for you because they offers you their stylish and elegant stone collection, expert design and flawless installation so that you can transform your kitchen and home into marble kitchen and marble bathroom.You can take idea of popularity of this company by their heavy customer group across the world.Their marble slab and granite countertops are imported across the world.This company is one of the best and largest provider of marble slab and granite countertops in California.If you are in California and worried about designing and installation of your home then leave all of your problem to marblecity.

Operating System Structure Part-2

2009-02-22T05:51:00.000-08:00

In the last post we had seen the first method in which an operating system can be structured i.e Simple Structure.From the last post about simple structure it is very much clear that this method is not very much efficient and there may be other structuring techniques that are much more efficient than simple structure technique.The most important thing for the success of any operating system structure is its hardware support,if an operating system got the proper hardware support then it can be broken into pieces that are more smaller and more effective then that of simple structure.If this is done successfully then an operating system can have much more control over the computer and the applications that are used by computers.In this post we take a look at the other method of making an operating system more modular i.e Layered Approach.

Layered Approach:-In this method of structuring the whole operating system is divided into a number of layers,in which the lowest layer represents the hardware part and the highest layer represents its user interface part.Each layer in this model is an implementation of abstract object model that contains objects and the routines that are required to access these objects.In layered approach a layer can only invoked the operations of its lower level layers.This approach helps very much in simplifying debugging and system verification.The first layer can be debugged without any concern for the rest of the system because their is no layer below the first layer and underlying hardware are assumed to be functioned correctly.Once the first layer is debugged,we can assume its correct functioning and we can debugged the second layer and so on.If an error is found during debugging of that layer then that error belongs to that particular layer because all the underlying layer are already debugged.Thus, the design and implementation of the system is simplified.
The main problem that exists with the layered approach is in defining the functions of every layer because a layer can only use its lower level layers for its functioning.One more problem that exists with this layered approach is that they tend to be less efficient than other types.For instance consider an example,when an user program executes an I/O operation,it executes a system call that is trapped to the I/O layer,which then call the memory management layer,which in turn call the CPU scheduling layer and then passes to the hardware.In this whole process,the each layer add its corresponding overhead result in that system call takes more time in comparison to the non-layered approach.

Operating System Structure Part-1

2009-02-21T05:51:00.000-08:00

If a system is large as well as complex then it is required that it must be designed carefully so that it can function properly and can be modified easily.The most common approach to achieve this is to partition the whole system into small components rather than having a single big structure.Now there are four approaches for achieving this.In this post we take a look at the first approach for structuring the system i.e Simple Structure.

Simple Structure:As all we know that every commercial system do not have well defined structure,the main reason behind this is,initially when these system are developed they developed as a simple,small,having limited functionality and then with time they started to grew up beyond their scope.The most common example of such type of a commercial system is MS-DOS.Initially when it was written the designers of DOS have no idea that this operating system became so popular in future.The main aim of designing this MS-DOS is to provide each and every functionality in a very limited space.So,in achieving this it was not divided into modules carefully.

In MS-DOS,the interfaces and level of functionality are not well separated.The major drawback of this thing is that application programs are able to access the basic I/O routines that means they can directly read or write to the basic display and disk drives.Due to this problem,the MS-DOS is very much vulnerable to the malicious programs,causing entire system crashes on the failing of user program.The other major problem with MS-DOS is that it is limited to hardware of its era because at that time the Intel 8088 for which it was written provides no dual mode and no hardware protection.Hence,in short we can say that their exists a lot of problem with this simple structure.

Parallel Communication

2009-02-19T04:20:00.000-08:00

Parallel communication takes place when the physical layer is capable of carrying multiple bits from one device to another.This means that the data bus is composed of multiple data wires,in addition to control and possibly power wires,running in parallel from one device to another.Each wire carries one of the bits.Parallel communication has the advantage of high data throughput,if the length of the bus is short.The length of a parallel bus must be kept short because long parallel wires will result in high capacitance values and transmitting a bit on a bus with a higher capacitance will require more time to charge or discharge.In addition,small variations in the length of the individual wires of a parallel bus can cause the received of data bits at the different times.

Such misalignment of data becomes more of a problem as the length of a parallel bus increases.Another problem with parallel buses is the fact that they are more costly to construct and may be bulky,especially when considering the insulation that must be used to prevent the noise from each wire from interfering with the other wires.For ex:-a 32 wire cable connecting two devices together will cost much more and be larger than a two wire cable.In general,parallel communication is used when connecting devices resides on same IC,or the devices that reside on the same circuit board.Since,the length of such buses is short,the capacitance load,data misalignment and cost problems mentioned earlier do not play an important role.

Cache Replacement Policy

2009-02-18T11:56:00.000-08:00

The cache replacement policy is the technique for choosing which cache block to replace when a fully associative cache is full,or when a set associative cache's line is full.One thing that you must note here is their is no choice in a direct-mapped cache that is a main memory address always maps to the same cache address and thus replaces whatever block is ready there.There are three common replacement policies for the cache.The first one is random replacement policy that chooses the block to replace randomly.While simple to implement,this policy does nothing to prevent replacing a block that is likely to be used soon.

The second replacement policy is least recently used(LRU) replacement policy replaces the block that has not been accessed for the longest time,assuming that this means that it is least likely to be accessed in near future.This technique provides for an excellent hit/miss ratio but requires expensive hardware to keep track of the times blocks are accessed.The third and last replacement policy is first in first out replacement policy uses a queue size N,pushing each block address onto the queue when the address is accessed,and then choosing the block to be replaced by popping the queue.

IC Technolgy

2009-02-08T09:39:00.000-08:00

Before we go in detail of IC technology first of all we have to understand what is IC,IC directly implies the Integrated Circuit.An IC,often called a chip,is a semiconductor device consisting of a set of connected transistors and other devices.Every processor must eventually implemented on an integrated circuit(IC).IC technology involves the manner in which we map a digital implementation onto an IC.A number of different processes exists to build semiconductor,the most popular of which is complementary metal oxide semi conductor(CMOS).IC technology is independent from processor technology that means any type of processor can be mapped to any type of IC technology.Now the main question that arises in front of us is what are the differences between the different IC technologies.

To understand the difference between different IC technologies we must first recognize that semiconductors consists of numerous layers.The bottom layers form the transistors.The middle layers form logic components.The top layers connect these components with wires.One way to create these layers is by depositing photo-sensitive chemicals on the chip surface and then shining light through masks to change region of the chemicals.Thus,the task of building the layers is actually one of designing appropriate masks.A set of masks is often called layout.

Cache Memory

2009-02-07T08:33:00.000-08:00

As all we know that,processing core and the memory are two integral parts of any CPU(Central Processing Unit).Now further this,memory is again divided into two categories slow memory and fast memory.Slow memory are RAM and hard disk,while Cache memory is the fast memory.The term slow and fast directly implies with the speed with which data can be accessed from these memory units.In simple words we can say cache memory is the memory that is used to store frequently used data so that the CPU doesn't have to wait for the data to be fetched from another slower storage areas like the system RAM or hard disk.

The main reason behind the fast accessing of data from cache memory is that it does not require refreshing of data and it is made of quite expensive static RAM.Once the data is stored in the cache, future use can be made by accessing the cached copy rather than re-fetching or re-computing the original data and this is what makes the average access time shorter. Cache, therefore, helps expedite data access that the CPU would otherwise need to fetch from main memory. The main advantage of cache memory is that performance of the CPU is increased to a great extent and it saves use of the read/write head which in turn extends its life too.Now a days cache memory is available in the range from 2 MB to 16 MB.

Single Purpose Processors

2009-02-06T09:42:00.000-08:00

A single purpose processor is a digital circuit designed to execute exactly one program.An embedded system designer may create a single purpose processor by designing a custom digital circuit.Alternatively,the designer may purchase a predesigned single purpose processor.Many people refer to this part of the implementation simply as the hardware portion,although even software requires a hardware processor on which to run.A single purpose processor when used in embedded systems,it has both advantages and disadvantages over the general purpose processors.If we look at the advantages of the single purpose processor,then by using single purpose processor performance may be fast,size is small,less power consumption and low unit cost for large quantities.On the other hand its disadvantages are very high design time,high NRE costs,low flexibility and high unit cost for small quantities.

General Purpose Processors

2009-02-05T11:57:00.000-08:00

A general purpose processor is a programmable device that is suitable for a variety of applications.The most important feature of these processors is program memory,that means the designer of such processors does not know what program will run on that processor,so the program cannot be built into the digital circuit.Another important feature of these processors is general datapath that means the datapath must be general enough to handle a variety of computations,so such a datapath typically has a large register file and one or more general purpose arithmetic logic units(ALUs).An embedded system designer,however need not be concerned about the design of general purpose processor.An embedded system designer simply uses a general purpose processor,by programming the processor's memory to carry out the required functionality.Using a general purpose processor in an embedded system may result in several design benefits.

Understanding BIOS/CMOS

2009-02-04T13:19:00.000-08:00

Though often interchangeably used, the two terms refer to different things. BIOS(Basic Input Output System) refers to asset of instructions that are critical for the functioning of the system .These instructions include information about the components connected to the motherboard, like the hard disk, RAM, and the configuration of the many onboard subsystems .CMOS (Complementary Metal Oxide Semiconductor) refers to the chip on which the BIOS instructions are stored. CMOS is the name of the technology behind the chip that stores the BIOS.Present-day CMOS is technically called EEPROM for Electronically Erasable Programmable Read-only Memory.These can be rewritten too, and this allows the BIOS instructions of a motherboard to be updated when required. The process of updating the BIOS instructions is called Flashing.

Flash Memory

2009-02-02T05:37:00.000-08:00

Flash Memory is the type of memory which is non-volatile in nature which means that it does not need power to maintain the information stored in the chip and primarily used in memory cards and USB flash drives for generals storage of data.You can also use these devices for transfer of data between computers and other digital products.The main advantage of using a flash drive is that it can be electrically erased and reprogrammed.Now if talk about the internal components of a flash drive then flash drive consists of a Flash Memory chip that stores the data, a controller that manages the read/write operations, and a USB interface.Now a days flash memory is also available as in non integrated form that means it can be plugged into Memory Card readers that have a USB interface.If we take a look at the advantages of the flash drives then it offers you fast read access times and better kinetic shock resistance than hard disks.In addition to this, when the flash memory is packaged in a memory card then it offers you very high durability,able to withstand intense pressure, extremes of temperature, and immersion in water.

Bad Sectors

2009-01-30T04:03:00.000-08:00

As all we know that a hard drive is made of the millions of sectors and it is possible that some of these sectors gone bad.As I a want to told you that when a hard drive is manufactured it still contains some bad sectors and as the life span of hard drive's increase or it gets old the number of bad sectors increased in it.A sector is a small area on the surface of the hard drive or a floppy disk.As all we know that each hard drive have several platters.The platters are the disc that are covered with magnetic material which is used to hold data and they are divided into a number of concentric rings known as track.If we talk about a floppy disk(1.44 MB) than it contains only one platter and having about 160 tracks.But in the case of hard drive it contains a lot of tracks and each track is divided into smaller storage areas called sectors.Now when a sector goes bad the whole data that it contains lost and it cannot be recovered.Bad sectors never affects the data of the remaining hard disk and disk is still completely usable.The main problem with the bad sectors is that it cannot be repaired,it only marked as unusable.Once you marked these bad sectors as unusable then operating system will never store data in these areas and storage capacity of your hard drive is decreased.

Avoid Swapping of Files

2009-01-23T07:54:00.000-08:00

When Windows loads, it moves certain parts of the operating system to the swap file anyway, regardless of whether it has run out of RAM or not. This is very good for systems with less memory, since it leaves some free RAM and applications will start much faster. Otherwise, when you start an application and memory is required, Windows will have to first move all this data to the swap file to free up RAM. This functionality is usually not required on systems with 256 MB or more RAM, especially if they only run common productivity tools such as Office and Internet applications. You can prevent Windows from using the swap file until absolutely required by adding the line below to the [386Enh] section of the \Windows\ system.ini file.

ConservativeSwapfile Usage=1 You can edit this file in Notepad. In case you face any problems such as programs crashing frequently, remove this line and reboot.

Enable your computer's DMA

2009-01-20T09:32:00.000-08:00

Direct Memory Access (DMA) is a technique that hard disks and CD-ROM drives can use to transfer data directly to and from memory, without passing through the processor. DMA reduces the load on the system processor since data transfers do not require monitoring by the CPU. With DMA, a write or read operation can be executed in two to four clock cycles. Without DMA it will cost the CPU a minimum of 16 clock cycles per operation. Not only do disk read/write operations gain a significant boost in speed, but Windows also works faster, since it can load system files much faster and also accesses the swap file at higher speeds. Older hard disks and CD-ROM drives do not support DMA, but almost all computers today use DMA-compliant devices. In case you face a problem after enabling DMA, reboot Windows to Safe Mode and disable the option. Also, DMA needs to be enabled from the BIOS, but again, on most computers, this is on by default. DMA is supported only in Windows 95 OSR 2 and later. To enable DMA, open Control Panel > System > Device Manager.Expand the Disk drives tree, select the hard disk and click Properties. Under the Settings tab, check the DMA option. Repeat this for all other hard disks and the CD-ROM or DVD-ROM drives.

File System Properties

2009-01-16T12:08:00.000-08:00

Changing the File System settings can also provide better performance. First, change your computer's role to a Network Server, even if it is not one. Open Control Panel > System > Performance and click File System. Under the Hard Disk tab, change the typical role of the computer to Network server instead of Desktop computer. The setting controls the size of various internal data structures used by the 32-bit file access driver (VFAT). When you use the Desktop computer setting, VFAT allocates memory to record the 32 most recently accessed folders and 677 most recently accessed files, consuming approximately 10 KB of memory. With the Mobile or docking system setting, VFAT allocates memory to record 16 folders and 337 files, taking up around 5 KB of memory. As a Network server, VFAT allocates around 40 KB of memory to record
64 folders and 2,729 files. With the kind of memory available on systems today, this slight overhead hardly makes any difference, especially considering the performance gain it provides.

Optimize your Virtual Memory

2009-01-15T01:36:00.001-08:00

The way virtual memory is configured tremendously affects Windows performance. This is true for all versions of Windows, including the now-obsolete Windows 3.1. The swap file is what Windows uses to store temporary data when it runs out of RAM. Thus, your working is not limited by the amount of RAM on your machine. However, for a program to be able to use this data, it must be transferred back to the RAM. The data that is not immediately required is moved to a part of the hard disk and recalled when required. However, since hard disks are nowhere as fast as RAM, swapping data back and forth drastically reduces speed. No matter how much RAM you have, Windows will always use the swap file for some infrequently used parts of the OS (read the next tip to see how to avoid this).

By default, Windows uses a variable swap file that is created on boot up and where the size is dynamically modified when required. Though this works just fine, it is not the most optimal. You can never get the speed of RAM from the hard disk, but you can make it slightly faster. The best way to configure the swap file is to have a permanent swap file, preferably on a dedicated partition. This minimizes the effect of disk fragmentation and increases seek time. Another practice that a few power users have adopted is to place the swap file on the first partition and the operating system on the following partition. Data closer to the center of the drive is read slightly faster than data at the periphery. This is especially useful for PCs with only 64 or 128 MB of RAM where data would frequently be swapped to the hard disk and can be easily done with BIOSes that allow booting from the D drive.

To change the swap file settings, open Control Panel > System > Performance and click Virtual Memory. Choose 'Let me specify my own virtual memory settings' and select the drive for the swap file. Note that no matter what partition you boot from, it will always appear as the C drive from DOS and Windows 98, and the first partition that is recognized as C by the BIOS will be assigned a higher drive letter. Set the minimum and maximum size for the swap file. Both these numbers should be identical to set a permanent (non-variable) swap file. Ideally, it should be two-and-a-half times the amount of RAM on your system, but if you have a separate partition for it, you may not want it to be less than 512 MB-if it is lower, it will have to be a FAT16 partition, not FAT32.

Concept of Thrashing

2009-01-14T05:58:00.000-08:00

If the number of frames allocated to a low priority process is lower than the minimum number required by the computer architecture then in this case we must suspend the execution of this low priority process.After this we should page out all of its remaining pages and freeing all of its allocated frames.This provision introduces a swap in,swap-out level of intermediate CPU scheduling.Let take a example of a process that does not have enough number of frames.If the process does not have the number of frames it needs to support pages in active use, it will quickly page fault.The oly option remains here for process is to replace some active pages with the page that requires a frame.However,since all of its pages are in active use,it must replace a page that will be needed again right away.Consequently,it quickly faults again and again that mean replacing pages that it must bring back in immediately.This high paging activity is called Thrashing.Or we can say that a process is Thrashing if it is spending more time in paging then executing.Thrashing results in severe performance problems.

Client Server Communication with the help of Sockets

2008-11-11T00:40:00.000-08:00

A socket is defined as an end point for communication between client and server.A socket is identified by a IP address concatenated with the port number.In general all sockets work on the client server architecture.In server client system, server waits for the incoming client request by listening to a specified port.Once the server received the request from the client it accepts the connection from the client socket to complete the connection.As there are some standards ports already defined for some specific services like a telnet server listens to port 23,a ftp server listen to port,a http server listens to port 80.All ports below 1024 are considered well known and we can use them to implement standard devices.Now when a client process requests to initiates a connection with the server,it is assigned a port by the host computer.This port is some arbitrary number greater that 1024.

Let us consider a example,there exists a client on host with IP address 185.145.23.87 wishes to establish a connection with the web server which is listening on the port 80 and having IP address 164.25.17.5,now let host X is assigned a port number 1547.Now this connection will contain a pair of sockets (185.145.23.87:1547) on host X and (164.25.17.5:80) on the web server.Now the packets traveled between the hosts are delivered to the appropriate process based on the destination port number.The main thing that kept in mind during connection that all connections must be unique,that means if another process on host X wants to establish a connection with web server then the port number that is assigned to this process must be greater that 1024 and different from 1547.

Hope you found this post useful.Waiting for your responses for further improvement.
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Understanding System Booting

2008-10-24T10:55:00.000-07:00

The procedure of starting a computer by loading the kernel is known as booting the system.In general every computer system has a small piece of code known as bootstrap program or bootstrap loader whose main task is to locate the kernel then load it into main memory and starts its execution.In some computers this process takes place in two steps in which in the first step a simple bootstrap loader fetches the more complex program boot program from the disk, which in turn loads the kernel(2nd step).Whenever any computer is powered or rebooted,the instruction register is loaded with a predefined location(at which bootstrap program is present),and execution starts their.This bootstrap program is in the form of Read Only Memory because RAM is in an unknown state at start up and in addition to this ROM is virus free because it is read only.In addition to this a bootstrap program perform a variety of task like to run diagnostics to check the state of machine.If the diagnostics is successful then the program is continued with booting steps.

All small application devices like cellular phones,PDA's and game consoles store their operating system in ROM.It is always recommended to store small operating system in ROM.But in the case of large operating system like Windows,Linux and Mac OS X or for the systems that change frequently,the bootstrap loader program is stored in firmware(ROM) and operating system is on disk. In this case the bootstrap runs diagnostics and has a bit of code that can read a single block at the fixed location from disk into memory and execute the code from that boot block.The program stored in the boot block may be sophisticated enough to load the entire the operating system into memory and begin its execution.Now after that full bootstrap program is loaded and it can traverse the file system to find the operating system kernel load it into memory and start its execution and at this point we can say that system is running.

Role of Timer in Operating System

2008-10-19T01:31:00.000-07:00

Timer in Operating System:As all we know that it is only the operating system that has full control over the CPU,and it is the primary duty of operating system to prevent user programs from getting stuck into an infinite loop or not calling to system services and never returning control back to the operating system.To accomplish all those services an operating system uses a device known as Timer.The main task of a timer is to interrupt the CPU after a specific period of time.This specific period of time is set by operating system and its value may very from 1 ms to 1 second.If the operating system is interested in using variable timer then it is implemented with the help of fixed rate clock or counter and in this case operating system sets the counter.

Working of Timer:Whenever the clock ticks,the counter is decremented.When the value of this counter reaches zero an interrupt occurs and control is transferred back to the operating system.Let's understand this with the help of example,A 10 bit counter with a 1 Millisecond clock allows interrupts at interval from 1 millisecond to 1024 milliseconds,in steps of 1 millisecond.Before turning control over to the user process an operating system ensures that timer is set to interrupt.Hence a timer can be used to prevent a user program from running too long.We can also initialize the value of counter with the amount of time that a process requires to complete its execution.For example,a program with 7 minutes time limit has its counter initialized to 420,and for every clock tick the counter is decremented by 1.Hence after 420 ticks the control is automatically transferred back to the operating system.

Dynamic Loading

2008-10-13T11:47:00.000-07:00

As all we know the an entire program and the data of all the process is always kept in physical memory for the process to execute this data.Here,in this situation the size of process is limited to the size of the physical memory.Here to obtain better space utilization we use dynamic loading.In dynamic loading a routine is never loaded into memory until it is called.All routines are kept on the disk in a relocatable load format.

First of all main program is loaded into memory and executed,now after this when a routine needs to call another routine,the calling routine first checks whether the other routine has been loaded.If the other routine is not loaded,then the relocatable linking loader is called to load the desired routine into memory and to update the program's address table to reflect this change. Then after this control is transferred to the newly loaded routine.The advantage of dynamic loading is that an unused routine is never loaded.This method is particularly useful when large amount of codes are needed to handle infrequently occurring cases such as error routines.

In all these cases the total program size may be large and the portion that is used may be much smaller.Dynamic Loading does not require any special support from the hardware or from the operating system.It is the responsibility of programmers to design their programs to take advantage of such a method.Sometimes operating system also helps the programmer by providing library routines to implement dynamic loading.

Logical Vs Physical Address space

2008-10-09T10:44:00.000-07:00

An address generated by the CPU is commonly refereed as Logical Address,whereas the address seen by the memory unit,that is one loaded into the memory address register of the memory is commonly refereed as the Physical Address.The compile time and load time address binding generates the identical logical and physical addresses.However, the execution time address binding scheme results in differing logical and physical addresses.

The set of all logical addresses generated by a program is known as Logical Address Space,whereas the set of all physical addresses corresponding to these logical addresses is Physical Address Space.Now, the run time mapping from virtual address to physical address is done by a hardware device known as Memory Management Unit.Here in the case of mapping the base register is known as relocation register.The value in the relocation register is added to the address generated by a user process at the time it is sent to memory.Let's understand this situation with the help of example:If the base register contains the value 1000,then an attempt by the user to address location 0 is dynamically relocated to location 1000,an access to location 346 is mapped to location 1346.

The user program never sees the real physical address space,it always deals with the Logical addresses.As we have two different type of addresses Logical address in the range (0 to max) and Physical addresses in the range(R to R+max) where R is the value of relocation register.The user generates only logical addresses and thinks that the process runs in location to 0 to max.As it is clear from the above text that user program supplies only logical addresses,these logical addresses must be mapped to physical address before they are used.

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Hina Rabbani Khar

User Operating System Interface Part-2

2008-10-07T03:21:00.000-07:00

Hello friends in the last post i told you about the one way command line interface through which an user can interact with the operating system.Now in this post i am going to told you about the second way through which an user can interact with the operating system.

The second approach through which an user can interface with the operating system is through Graphical User Interface(GUI).This interface provides a mouse based window and menu system as an interface to the user,rather than entering commands through command line interface.A GUI provides a desktop metaphor where the mouse is moved to position its pointer on images,or icons,on the screen(desktop) that represent programs,files,directories and system functions.Depending on the mouse pointer location,clicking a button can invoke a program,select file or directory which is known as folder.Microsoft's first version of Windows version 1.0 was based upon a GUI interface to the MS-DOS operating system.Then after this various versions of windows systems proceeding its initial version had been developed Windows 98,Windows 2000,Windows XP and Windows Vista.

The choice of whether to use a command line or GUI interface is mostly depend on individual to individual.As a very general rule,many UNIX users prefer a command line interface because they provide powerful shell interfaces.Alternatively, most Windows users are pleased to use the Windows GUI environment and almost never use the MS-DOS shell interfaces.

User Operating System Interface

2008-10-05T23:14:00.000-07:00

Hello friends in this post i am going to told you about the ways through which an user can interact with the operating system.

There exists two fundamental approaches through which an user can interact with the operating system.First technique is command line interface or command interpreter with the help of which an user can directly enter commands and further these commands are executed by operating system.The second approach is GUI(Graphical User Interface) in which user gets graphical interface to interact with the operating system.Now first begins with command line interface.

Command Line Interface: The main function of the command interpreter is to get and execute the next user-specified command.Many of the commands given at this level manipulate files:create,delete,list,print,copy and so on.The MS_DOS and UNIX shell operate in this way.Now here also exists two ways in which these commands can be implemented.

The first approach implies that, the command interpreter itself contains the code to execute command.For ex: suppose we entered the command 'delete' to delete a file,then in this case the command interpreter jump to a section of code that sets up the appropriate parameter and sets the appropriate system call.The summary of this method is that command interpreter has itself its code for executing the command.

In the second approach whenever users enter any command the command interpreter did not understand the command in any way,what it does, it merely used the command to identify a file to be loaded into memory and executed.This approach is used in UNIX operating system.Thus the UNIX command to create a file is create file.txt. Now the UNIX operating system search for the file create,load the file into memory,and execute it with the parameter file.txt.The function that is associated with the create command would be defined completely by the code in the file create.With the help of this approach an user can add new commands to the system by creating new files with the proper names.

Operating System Services Part-2

2008-10-03T02:59:00.000-07:00

Hello friends in the last post i told you about the services that an operating system provides to its user.Now in this post i am going to told you about the services that an operating system provides to itself for the efficient working of it.

1.Resource Allocation:Suppose when there are multiple users or multiple jobs exists at the same time,resources must be allocated to each of them.The main task of operating system is to manage all these resources.Some resources such as CPU cycles,main memory and file storage may have special allocation code,whereas others such as I/O devices may have much more general request and release code.To use all these resources in the best efficient way operating system have CPU scheduling routines that take into account the speed of the CPU for the CPU resources.There may also be routines to allocate printers,modems,USB storage drives,and other peripheral devices.

2.Accounting:If we desire to keep track of which users use how much and what computer resources then operating system also provides this facility in the form of accounting.This record keeping may be used for for billing purpose of the users or simply for accumulating usage statistics.Usage statistics may be a valuable tool for researchers who wish to reconfigure the system to improve computing services.

3.Protection and Security:When several separate processes execute concurrently,it should not be possible for one process to interfere with the others or with the operating system itself.Protection involves ensuring that all access to system resources are controlled.Security of the system from the outsiders is also an important issue.Such security starts with requiring each user to authenticate himself or herself to the system,usually by means of a password,to gain access to system resources.This security is also applicable to the external I/O devices,including modems and network adapters from invalid access attempts .If a system is to be protected and secure,precautions must be instituted throughout it.

Hope you enjoy this post.Waiting for your response for more improvement.

Process management in operating system

2008-10-02T01:31:00.000-07:00

Hello friends from now onwards i am going to discuss various concepts of operating systems that are very necessary to grasp the fundamentals of operating systems.In the post i am going to discuss the process management in operating system.

Before i begin with process management first of all we have to understand what is a process.In simple words we can say that a process is a program that is running on our computer.Now this process may be running either in frontend or in backend of the computer.Each and every process is composed of one or more than one thread.It is possible that an operating system may contain more processes running than actual programs because some processes are running in the backend of the operating systems.Now we came to our main issue of process management.As all we know a process needs some resources like cpu time,memory files and I/O devices for the execution of its instructions.Sometimes these resources are allocated to the processes when they are created or sometime when they are in running state.Sometimes in addition to these resources we have also pass some initialization data that is known as input for the process.

To understand the concept of process management we have to very much clear about the terms process and program.The main difference between these two terms is that process is an active entity while program is a passive entity.Generally the management of each process is done with the help of program counter,in case of a single threaded process it has one program counter that specifies the execution of the next instruction.The execution of these process are sequential in nature.The CPU executes next instruction only when it successfully executed the previous instruction.In case of multi threaded process they have multiple program counters each pointing to the next instruction to execute a given thread.

A process is a unit of work in the system.These types of systems are collection of the process some of which are them operating system process that execute system code and some of them are user system process that executes the user code.In addition to process management, operating system is also engaged in various activities like:
-->Creating and deleting both user and system process.
-->Suspending and resuming process.
-->Providing mechanism for process synchronization.
-->Providing mechanism for deadlock handling.

Operating System Services

2008-09-30T22:29:00.000-07:00

Hello friends now its time to move forward with operating systems.In this post i am going to told you about the services that an operating system provides to a user.

Generally operating systems provide two types of services one that is provided to the programs and the other that is provided to the users of these programs.These operating system services are provided for the convenience of the programmer i.e to make the programming easier.Now lets begin with the first type of service that is provided to the user:

1.User Interface:As all we know almost all operating systems has user interface.Now this interface can be of any form either it may be command line interface,which uses text commands and a method for entering them or it may be graphical user interface(GUI) .In GUI the interface is a window system with a pointing device to direct I/O,choose from menus,and make selections and a keyboard to enter text.

2.I/O operations: Whenever a program is running it requires some I/O resources to complete its execution.For specific devices, special resources may be required such as a cd or dvd driver to for recording of a cd or dvd.For efficiency and protection,users cannot control I/O devices directly.Hence operating system provide some means to do I/O.

3.File system manipulation: The file system manipulation is a different area of interest.As all we know that some programs need to read and write of files and directories.They also need to create and delete them by name,search for a given file and list file information.So for doing all these instructions some program is required that include permissions management to allow or deny access to files or directories based on ownership.

[caption id="attachment_57" align="aligncenter" width="397" caption="Services that an operating system provides to its users".

4.Communications: Sometimes their exists a situation in which one process needs to exchange information with another process.Such communication may occur between the processes that executing on the same computer or between processes that are executing on different computer systems but exists in same computer network.Now this communication may be implemented by shared memory or through message passing,in which packets of information are moved between processes by the operating system.

5.Error Detection: One of the most important service that is provided by an operting system to its user is error detection.Error may occur in CPU,in memory,in I/O devices(such as parity error on tape,a connection failure on the network) and in the user program(such as arithmetic error,an attempt to access an illegal memory location).For each type of error,the operating system should take appropriate action to ensure correct and consistent computing.

All these are the services that are provided by an operating system to its user.
Hope you enjoy this post.Waiting for your comments for more improvement.

Caching in Operating Systems

2008-09-30T05:12:00.000-07:00

Hello friends in the last post i told you about the memory management in operating systems,now in this post i am going to tell you about the caching i operating system.

Caching is an important principle of computer systems.As all we know all information is kept in some storage such as main memory,as it is used,it is copied into a faster storage system-the cache-on a temporary basis.When we need a particular piece of information,we first check whether it is in cache or not,if it is in the cache we use it directly from the cache,otherwise we use the information from the source from where it is present and made a copy of that information in the cache assuming that we will need it again soon.By doing so we decreases the searching time of that particular information.

As all we know that the purpose of cache is to speed up memory accesses by storing recently used chunks of memory.Now why the need of caching or cache memory is required because as all we know that access from main memory into a register may take 20-50 clock cycles,but in the case of cache memory it reduces to single clock cycle.That's why cache memory or caching is needed.But the cache memory that we used is very expensive in cost that's why we can't compose our main memory entirely of it.

Thats why we have only very limited amount of cache,and we can store only limited amount of data in it,now the main question that arises here is that to store which data from the great chunk of data.For this we only save that data that is most recently used.Sometimes this policy is also known as the spatial and temporal locality.When we want to access memory at a certain address, we look in the cache to see if it is there. If it is there, we get it from cache instead of going all the way to memory, that situation is called a "cache hit." If the data is not in cache, then we bring the data from memory to cache, which takes longer since the data must be brought in from the smaller memory, that situation is called a "cache miss," and that delay that we endure because that memory must be brought from main memory is called a "miss penalty".

Hope you enjoy it.Please give your comments for more improvement.

Memory management in operating systems

2008-09-28T21:46:00.000-07:00

Hello friends this is my first post and in this post i am going to told you about memory management in operating systems.

If we talk about the memory management then it simply means that we are going to manage only the main memory(RAM) not secondary memory(Hard disk).As all we know that main memory is central to the operation of a modern computer system.The main task of a memory manager is to made available the memory first to the primary process then to the other.If we talk about the main memory we know that it is a large array of words or bytes ranging from millions to billions.Each word or byte has its own address.The central processor reads instructions from the main memory during the instruction fetch cycle and both reads and writes data from the from the main memory during the fetch cycle.

The main memory is only the memory that a CPU can access directly otherwise for accessing any instruction from disk then it first transferred to the main memory then CPU executes it.For a program to be executed it must be mapped to the absolute address and loaded into memory.Now as the CPU executes this program the its accessing instructions and data by generating their absolute addresses.Eventually when this program terminates it releases its occupied main memory and this memory is allocated to the next program and loaded in it.Now to improve both CPU utilization's and its speed of computer response to its users,general purpose computers keep several programs in memory,creating a need for memory management.Today there exists a lot of memory management schemes but to select a particular management scheme is totally depends on the situation or sometimes it depends on the hardware design of the system.

Each algorithm requires its own hardware support.Now in addition to memory management CPU is also engaged in various activities of memory.

Keeping track of which part of memory are currently being used and by whom.

Deciding which process or data to move into and out of memory.

Allocating and Deallocating memory space as needed.

Introducing Blog

2008-09-28T21:26:00.000-07:00

Hello friends this is my first blog and in this blog i am going to explore all the important concepts of operating system in which students find themselves in difficulty.Here you will find a complete description of all the topics that will really help you in understanding these concepts.In this blog I will also provide you a great comparison of different types of operating systems like Windows XP,UNIX,LINUX and Macontish according to their services.In this blog you will also found some latest hacking technologies in Windows XP,UNIX and Linux that will definitely a fun stuff for you.In addition to this i also give you latest news from the field of technology and also some reviews.

Hope you enjoy it.