Study On CPU And Memory Hierarchy

Study On CPU And Memory Hierarchy CPU must have compatibility with the memory in the computer system. Memory cannot increase the speed of the processor however it can help the processor increase its performance. If the CPU doesnt get the data it requires, it would sit idle wasting CPU clock cycles that would decrease the overall throughput and execution of the processes. If data needs to be accessed to and from hard disk which is slower as compared to the main memory, more and more cycles are wasted decreasing the efficiency of the system. Conclusion- For better performance of the system, faster program execution and proper CPU utilization the compatibility between CPU and memory is required. A computer employs RAM chips of 256*8 ROM chips of 1024*8. The computer society system needs 2K byte of RAM 4KBYTE of ROM, 4 interface units. Each with 4 registers. A memory mapped I/O configuration is used. The 2 highest order bits of the address bus are connected with address 00 or RAM and 01 for ROM 10 for interface. How many RAM ROM chips are needed? Draw a memory address map. 2 kb of RAM required i.e. 21024(bytes) =2048 bytes (Since 1 kb =1024 bytes) RAM = = 8 chips; and 4kb of ROM is required i.e. 4 x 1024 = 4096 bytes Therefore ROM = = 4 chips; and There are 4 interfaces each having 4 register, So total no. of registers is 44=16 registers; Memory address map Cache Coherence- Caches allow greater performance by storing frequently used data. In multiprocessing system, each processor is provided with its own cache and they all share the same memory or address space so it is possible for more than one processor to access a data item at a time. What if one processor updates the data item without informing the other processors, inconsistencies may result and cause incorrect executions and the problem of inconsistencies is known as Cache Coherence in computing. The coherence of caches is obtained if the following conditions are met. However these read and write operations are said to be one after another and this is not possible due to memory access latency and a write by first processor may not be seen by a read from second processor if the read is made within a very small time after the write has been made. Case 1 Case 2 Processor P1 reads memory location X and then writes back to same location X while no other processor is not accessing the memory location X. Processor P1 reads and then processor P2 writes to and from same location X and currently the location would return value written by processor P2 only. Processor P1 and P2 writes to same memory location X in a sequence and currently the value returned would be decided as per the sequence. Mechanisms- Bus Snooping- In Bus Snooping each cache is connected through the same bus and it is where every CPU knows who has a copy of its cached data. So each CPU watches continually for write activity concerned with data addresses which it has cached. This assumes that all communication can be seen by all. However it is far more complex to implement. Directory Based Approach- In a directory-based system, the data being shared is placed in a common directory that preserves the coherence connecting caches. The directory acts as a filter through which the processor must ask authorization to fill an entry from the primary memory to its cache. When an entry is distorted the directory either updates or invalidates the other caches with that entry. The MESI protocol is the best suited protocol to avoid cache coherence, where M stands for MODIFIED, E stands for EXCLUSIVE, S stands for SHARED and I stands for INVALID. Write Back Cache- Cache uses two approaches to write data back to main memory. Write Through Write Back It is the simplest one in which all write all operations are made to the main memory as well as to cache; ensuring main memory is always valid. Any other CPU- cache module can monitor traffic to main memory to update the data in its own cache, but always results in substantial memory traffic. It minimizes memory writes. In write back method modifications to data in the cache arent copied to the cache source until absolutely necessary. It is also known as copy back cache .In write back updates are made only in the cache. When an update occurs UPDATE bit are set associated with the slot and when the block is replaced it is checked whether the UPDATE bit is set or not. If it is set then data is written back to main memory. For Example- Intel processors since the 80486 uses back caching. Problem with this kind of implementation is that performance improvement comes with a slight threat that data may be vanished if the system crashes and more complex circuitry. Onboard Cache- Cache is a part of multi-level storage strategy which is used to increase the performance of CPU by providing a bridge in between the slower memory RAM and CPU. The cache that is the part of the CPU is known as off-board cache and the cache which is present on the motherboard is known as on-board cache. Generally L1 cache is referred as off-board and L2 is known as on-board. Sometimes L3 cache is also present on the motherboard along with L2. Now a days specific CPU vendors incorporates L2 as a part of CPU and L3 on motherboard. Implementation of Cache- In Cache, latency needs to be decreased and hit rate needs to be increased. Larger caches have better hit rates but longer latency. To address this problem, many computers use multiple levels of cache. The smaller and faster one is L1 cache built inside the CPU known as on-chip. If CPU needs data it first checks in L1; if it hits the processor proceeds at high speed. If the smaller cache misses, the next larger cache (L2) is checked, and so on, before external memory is checked. As the latency difference between main memory and the fastest cache has become larger, some processors have begun to utilize as many as three levels of on-chip cache. For Example- Intels Xeon MP Product code-named Tulsa, AMD Phenom II (2008), Intel Core i7 (2008) uses unified L3 cache. However Cache can be implemented by using Direct Mapped, Associative Mapping or Set-Associative Mapping. Virtual Memory- For the execution of programs memory required is more than what is actually present. So, the technique used to overcome this size limitation is Virtual Memory which is illusion of memory not physically present. The purpose is to allow multiple programs share same memory allowing splitting up of program into smaller pieces that can be loaded into different parts of memory whenever space can be found. Implementation of Virtual Memory- It is implemented using two techniques- one is Demand Paging and other one is Demand Segmentation. CPU generates address which is not physically present. These are the program addresses referred to as logical addresses, they dont have any existence outside the program, the actual memory addresses are known as physical addresses. These virtual addresses are mapped or interchanged to its corresponding physical address through a process known as mapping. A page table or look up table is maintained for this purpose. In Demand paging, valid-invalid bit scheme is used in which a valid-invalid bit is associated with each page. 1 for the page in memory and 0 for not present in memory. During address translation if bit in entry is 0 the page fault occurs. In virtual memory process are divided into chunks of equal size known as pages and chunks of memory in which pages are loaded are known as frames. In Demand Segmentation each row of the lookup table contains a starting address for a logical block of memory, together with the size of the block and a corresponding starting address in physical memory. Paging and Segmentation operates both the same. Problem of Fragmentation- Fixed Memory Partitioning- Operating system occupies fixed portion of main memory and partitions are created for multiple processes but not of same size, so there will be wastage of memory. In most cases the process will not acquire memory provided to it. Variable Memory Partitioning- In variables-size partitions, the memory allocated is as much it is required by process. However when processes are swapped in, small holes are created leading to problem of fragmentation. Compaction is done to solve problem, but it waste CPU time. In Virtual Memory demand paging method is implemented, in which memory is partitioned into equal chunks that are relatively small, and each process is divided into small fixed size chunks of some size. The lists of the frames that are free are maintained by the operating system. As the size of the pages and frames are same so suffer less fragmentation problem. The Memory Hierarchy The design constraints on a computers memory can be summed up by three questions: how much memory is available, how fast it is and how much it will cost? Following are the relationships between these tradeoffs- Smaller access time, greater cost per bit. Greater capacity, smaller cost per bit. Greater capacity, greater access time. Access Time Increase Transfer Rate DecreasesCPU Registers Cache Cost per/bit Decreases Capacity IncreasesRAM Magnetic Disk Figure -Memory Hierarchy Memory hierarchy helps in increasing the performance of processor, without hierarchy, faster process wont help and all time waiting on memory, It provides a large pool of memory that costs as much as the cheap storage near the bottom of the hierarchy, but that serves data to programs at the rate of the fast storage near the top of the hierarchy. It provides a faster access of data stored in the memory. If it is understand how the system moves data up and down the memory hierarchy, then application programs can be written so that data items are stored higher in the hierarchy, where the CPU can access them more quickly. Addressing modes affecting performance of system- It simplifies the memory references, produces variable length instruction format and instruction manipulates operands in memory directly. It adds convenience and flexibility to have modes of addressing, and it allows a large range of addressable memory while using a reasonable number of bits. Addressing modes make it easier to write certain type of programs such as loops that uses an index to address different entries in a table or array. For Example- Indexed Addressing. Now a days computer allows programmer accessible registers that manipulate data directly between registers.

Abolitionists Essay -- essays papers

Abolitionists Strategies of Sojourner Truth, Harriet Tubman, and John Brown Abolitionist Movement was a reform movement during the 18th and 19th centuries. Often called the antislavery movement, it sought to end the enslavement of Africans and people of African descent in Europe, the Americas, and Africa itself. It also aimed to end the Atlantic slave trade carried out in the Atlantic Ocean between Africa, Europe, and the Americas. Many people participated in trying to end slavery. These people became known as the abolitionists. The three well-known abolitionists are Sojourner Truth, Harriet Tubman, and John Brown. Sojourner Truth (1797-1883), born into slavery as Isabella, was an American abolitionist and an advocate of women's rights. She joined the abolitionist movement and became a travelling preacher. She took her new name-Sojourner Truth-in 1843 and began preaching along the eastern seaboard. Her strategy consisted of walking through Long Island and Connecticut, speaking to people about her life and her relationship with God. She was a powerful speaker and singer. When she rose to speak, wrote one observer, "her commanding figure and dignified manner hushed every trifler to silence." Audiences were "melted into tears by her touching stories". She traveled and spoke widely. Encountering the women's rights movement in 1850, Truth added its causes to hers. She is particularly remembered for the famous "Ain't I a Woman?" speech she gave at the woman's rights convention in 1851. Although Truth never learned to read or write, she dictated her memoirs to Olive Gilbert and they were published in 1850s as The Narrative of Sojourner Truth: A Northern Slave. This book, and her presence as a speaker, made her a sought-after figure on the anti-slavery woman's rights lecture circuit. Harriet Tubman was closely associated with Abolitionist John Brown and was well acquainted with other abolitionists, including Frederick Douglas, Jermain Loguen, and Gerrit Smith. After freeing herself from slavery, Tubman worked at various activities to save to finance her activities as a Conductor of the Underground Railroad. She is believed to have conducted approximately 300 persons to freedom in the North. The tales of her exploits reveal her highly spiritual nature, as well as a grim determination to protect her charges and those who aided t... ... others to do what she needed them to do. Her subjects listed to what she had to say and were encouraged enough by her words not to give up and to continue their journey to freedom. As a result of the abolitionist movement, the institution of slavery ceased to exist in Europe and the Americas by 1888, although it was not completely legally abolished in Africa until the first quarter of the 20th century. While the abolitionist movement's greatest achievement was certainly the liberation of millions of black people from servitude, it also reflected the triumph of modern ideas of freedom and human rights over older social forms based on privileged elites and social stratification. Bibliography: Baines, Rae. Harriet Tubman-The Road to Freedom. New Jersey: Troll Asssociates, 1982. Bernard, Jacqueline. Journey Toward Freedom-The Story of Sojourner Truth. New York: Norton Publishers, 1967. Ripley, Peter C. The Black Abolitionist Papers. Chapel Hill: University of North Carolina Press, 1985. www.askjeeves.com Visited site November 14, 2001 www.encarta.msn.com Visited site November 14, 2001 www.encyclopedia.com Visited site November 14, 2001

The Colliding Dynamics of Class Structure Essay -- Social Studies

The rigidity of class structure is the culprit for the vast number of inequities in society. Power is concentrated in the hands of a small sector; leaving a few individuals to have more authority and influence, in comparison to others. The construction of class structure identifies the way groups are divided into social positions. Differences stemming from social position are further exemplified by the accessibility to valuable resources–such as wealth, education, occupation, and status. Those with distinguished command in society have access to these increasingly wide ranges of resources, which may be present in limited forms to the less powerful. Used as a device of supremacy, power is a style of control when the basis is acquiring these societal possessions. Even though class structure is considered to be fluid in nature, for some it is a complex web of entanglements hard to deal with it. Groups who suffer from social and material deprivations are not doing so by choice, b ut hugely in part to economical and occupational factors. These prominent distinctions have led several to fall victim to the systems of hierarchy. Built within these schemes are the inequalities that arise due to one’s position; and captured inside are the outcomes that influence levels of individual, educational, and occupational independence. People who do observe the inequities between classes may feel the impact of social stratification in various ways. Similarly the dynamics of class structure are very significant elements found throughout the works of Virginia Woolf, George Orwell, and Karl Marx. They are all in agreement that society host the series of conflicts underlying that of class structure. Class structure as a whole denotes differing realit... ...ist Feminism." Critical Sociology (Brill Academic Publishers) 25.2/3 (1999): 196-217. Academic Search Complete. Web. 19 Mar. 2012. Marx, Karl, and Frederick Engels. Marx/Engels Selected Works, Vol. One. Moscow. Progress Publishers, 1969, N. pag. http://www.marxists.org/archive/marx/works/1848/communist- manifesto/index.htm. Web. 23 Apr. 2012. Orwell, George. "Shooting an Elephant". The Seagull Reader Essays. 2nd Edition. Ed. Joseph Kelly. New York. W. W. Norton & Company, Inc, 2008. 243-250. Print. Peet, Richard. "Inequality and Poverty: A Marxist-Geographic Theory." Annals of the Association of American Geographers 65.4 (1975): 564-571. Academic Search Complete. Web. 19 Mar. 2012. Woolf, Virginia. A Room of One's Own. New York. Quality Paperback Book Club, 1992. Print. Woolf, Virginia. Three Guineas. New York. Quality Paperback Book Club, 1992. Print.

Music: the Medicine of the Mind

Music can have effects on the human brain that are hard to exaggerate. For instance, a mere snippet of song can trigger one’s memories so vividly. A tune can induce emotions ranging from unabashed joy to deep sorrow and can drive listeners into states of patriotic fervour or religious frenzy–to say nothing of its legendary ability to soothe the savage beast. The study of how music affects the mind and the interconnection between music and the physical and mental health of human beings has been a subject of interest for many.Music is known to speed the recovery of health ailments and has a calming effect on the mind. Music helps fight anxiety and has a soothing effect on the brain. Music may affect the brain/mind by increasing creativity and problem solving skills; concentration and memory; and speeding up healing. Music increases creativity and problem-solving skills. Music enhances creativity, by positively impacting the right side of the brain where most of oneâ€℠¢s creative thought is situated and triggering brain centres which deal with enhancing creativity.For example, according to the article â€Å"Healing by Music Therapy – Ragas† From the online magazine: ‘Akhand Jyoti’, certain ragas (A pattern of notes in Indian music that have characteristic intervals, rhythms, and embellishments, used as a basis for improvisation) activate the chakras of the body, thus giving the individual an added advantage in other creative tasks. Additionally, music increases spatial and abstract reasoning skills required in tackling problems, solving puzzles and decision-making.Moreover, according to Eric H. Chudler, Ph. D. , a lecturer at the Washington University Faculty of Music, â€Å"the brain responds to the â€Å"Mozart Effect†; listening to classical music for a period of 10 minutes appears to increase your creative abilities. † Therefore, listening to Mozart's music positively affects the spatial-temporal reaso ning, simply put; it ‘makes one smarter’. Furthermore, music increases concentration levels and improves memory.According to the online article â€Å"The Brain on Music† by the neurologist Dr. Ellen Weber; â€Å"Classical music, such as Haydn and Mozart, often improves concentration and memory when played in the background. † Hence, music helps increase your concentration levels a great deal. In addition, music has a calming effect on the mind, so, the calmer the mind, the easier it is to focus and concentrate. Additionally, music has been found to increase memory levels of Alzheimer's and dementia patients.The silence between two musical notes triggers brain cells which are responsible for the development of sharp memory. Flute music, and instruments like the santoor and sarod are recommended for the enhancement of concentration and memory. Also, classical music improves the ability to recall what's retained in the brain in the form of memory. Strong beat s cause the brain waves to resonate in synch with the beat, thus, leading to increased levels of concentration and increased mental alertness. Moreover, music acts as a catalyst in the healing process.According to the online article â€Å"Music and the Healing Process† from the Thorburn Associates Acoustic and Technology Consultants website, â€Å"There is also significant research that music can be used in medicine to help manage pain, reduce anxiety†¦Ã¢â‚¬  Hence, music is an effective distraction from pain and suffering of the sick and injured, however, music not only diverts the mind from pain, but also helps bring about certain chemical changes in the brain, such as, enabling one’s mind to secrete endorphins that speed up the process of healing.As a result, music therapy is recommended for patients of high blood pressure, heart diseases and even cancer, so, music may be considered as therapeutic in pain management. Therefore, listening to melodious, comfort ing music is sure to have a positive effect on the physical and mental well-being of patients. If not cure every ailment, music definitely creates hope in the minds of patients – a hope to recover. And when nothing else works, only hope does. To sum up, increased creativity and problem solving skills; concentration and memory levels; and speedy healing, are the effects music has on the mind/brain.Music really affects the human mind a great deal. So much so, that it influences one’s physical and mental state. Music aids in the speedy recovery of ailments by diverting the mind away from the pain as well as through chemical changes in the brain brought about by music which catalyse the healing process. In addition music calms the mind, helps fight anxiety and has a soothing effect on the brain, thus, increasing one’s concentration and memory levels. Lastly, through triggering brain centres and stimulation of the right side of the brain, music enhances an individual ’s creativity and problem-solving skills.

Man’s Innate Evil †“Lord of the Flies” by William Golding Essay

The Savage inside us all, when certain situations are brought up the primitive human nature is unleashed. Aspects of human nature in the world alert us to our potential to descend from law and order to chaos, good to evil and civilization to savagery. The break down of civilization towards savagery dramatizes the struggle between the ruling element of society which include law, morality, culture and the chaotic element of humanity’s savage instincts which include anarchy, amorality, and a desire for power. Throughout the novel, Lord of the Flies, Golding explicitly articulates that circumstances creates decay in moral value, innocence of human being and deteriorates the democratic system. Ralph the leader is the symbols for morality and leadership, while their enemy Jack is the symbol for the desire for power, selfishness and amorality. Simon the intellect who was the only boy who realizes fear is innate and the beast is within the boys. Lord of the Flies reveals how people ca n descend into barbarism in an atmosphere of chaos. The protagonist, Ralph, who personifies order, pragmatism, and everyman’s natural weakness, displays power and influence in the beginning but is almost tempted into savagery in the end; his use of the conch in the beginning of the book exhibits his characteristics and his civilized nature. He at first is presented as an activist individual, but also possesses an innate savage nature like everyone else and this is displayed when he partakes in the killing of Simon. Dont you understand, Piggy? The things we did He may still be. Although Ralph commits murder, he is still not completely submerged into savagery since he is able to realize what they have done, and this is clearly allegorized when he says he is afraid of them and wants to return home. These examples of Ralph show that when humans are not under the right circumstance, or away from civilized world they are most likely to unleash their inner selves their evil side. They also show how Ralph descended from Civilization to Savagery. In spite of Ralph’s display of civility, wisdom and the confident view for man’s fate, Jack on the other hand reveals the credence of man’s fall into savagery. Jack, who personifies savagery, bloodlust, and the hunger for power, shows the unavoidable fate of man. When Jack painted his mask, he had liberated  from shame and self consciousness. This is one of the major turning points for the alteration of Jack’s character is his relevance of the mask. Jack’s hiding behind the mask is a way for him to unleash his savage nature without feeling repentance. He also desires power from the beginning of the novel to the point when he declares himself the new leader. Jack persuades the boys to join him by using fear about the beast, and he does so until they all come to believe in its existence. After Jack diffuse this fear and belief in the boys’ minds, all aspects of civilization, culture and dissolve quickly. Absurdity emphasizes Jack’s bloodlust when he kills the sow and when he attempts to kill Ralph also. Jack hunts not with the sole intention to get meat, but he particularly enjoy exercising power over living creatures while hunting. Though it is not accomplished, Ralph’s potential murder also illustrates Jack’s ridiculous and savage nature. Jack is completely descended from good to evil in an atmosphere of chaos. On the opposite side Simon is the only boy on the island who really knows who the beast is. Simon was the only boy who did not descend into savagery. He is really the only one on the island who realizes that the fear is innate and that there is no beast. What I mean is†¦ maybe it’s only us. Simon’s delirious confrontation with the Lord of the Flies confirms his theory of evil being instinctive to man and actually within all of us There isn’t anyone to help you. Only me. And I’m the beast†¦ fancy thinking the Beast was something you could hunt and kill! †¦ You knew didn’t you? I’m a part of you. These examples validates that savagery was always there in mankind but need a proper circumstance to come out. So when Simon climbs the mountain and sees the parachutist and comes back to tell everyone that there is no beast, the inner beast of the boys made them kill Simon thinking that it is the beast. As Jack had implanted that there is a beast in real into their brains. Even after Simons death Jack and his tribe did not stop hunting and did not think about the murder they did the night before. The inner beast led to the loss of religion, and turned Jack and his tribe into complete savages. These are examples of the events that happened away from the civilized world. Simon the only boy to know the original beast mans innate evil. Jack turning completely savage; and Ralph the leader who was often tempted by the  savagery of the others. All the above examples conclude that aspects of human nature in the world alter us to our possibility to descend from law and order to chaos, good to evil and civilization to savagery. Lord of the Flies showed that the evil residing within everyone could be unleashed. It proved the dark side of human nature could be really brutal and even the most innocent of us are vulnerable to it. Bibliography â€Å"Lord of the Flies†, William Golding, The Berkley Publishing Group, New York, 1954

MGMT3010 Essay Example | Topics and Well Written Essays - 500 words

MGMT3010 - Essay Example The last tier makes sure that the policies which are in practice are kept in such a manner that these benefit the organization in entirety. The four tiers within the functional experts are significant at gaining an understanding of the organization and the different roles that come about in the wake of changes and amendment happening from time to time. The benefits of the functional experts would in terms of providing value to the investors, customers and employees in essence. As far as the strategic partner is concerned, this helps in facilitating and coordinating strategies which benefit the employees and indeed the organization in the long run. It makes the tasks of all people easier without a doubt. The management reaps the dividends under such quarters because the processes play their significant role at benefiting the people at large. The strategic partner tries to integrate the different sectors within the business domains to make sure that there is a smooth operational regime in place. The strategic partner links up with the tasks with the resources which are available at their disposal and make sure that all the anomalies are taken care of without any hindrances. The strategic partner has always been an important element of any organization as its role is undoubted and there seem to be no issues which engulf their respective selves.

Strategy Development in the Global Oil, Gas and Petrochemical Industry Essay

Strategy Development in the Global Oil, Gas and Petrochemical Industry - Essay Example However, with the passage of time, the company realised that they had to compete with other companies in the global arena. Oil companies such as Exxon were giving Shell a run for their money because they were globally managed. In order to respond to this trend, the company opted to change its corporate governance style. They opted to control almost all their downstream sectors through their headquarters in London and The Hague. (Shell, 2008) Corporate governance within Shell had been carried down from almost a century of its existence. In certain scenarios, some critics have argued that this form of structure has cost the company in a number of ways. This is largely because shareholders in the company do not have as much clout as members of the board. The disadvantage of this structural approach can arise when the shareholders feel that their rights are in danger but can do very little to protect it. Bp has been faced with a number of corporate governance challenges. First and foremost, the company grappled with accusations from critics who claimed that it was doing business with a group that had been responsible for human rights abuses in the Baku Ceyhan pipeline. To add insult onto injury, BP was also faced with huge problems in its pricing strategies. This was especially seen in the United Kingdom. In Colombia, the Company was confronted with a law suit where it had been accused of colluding with terrorists to protect their clients. It lost millions of pounds in paying off that settlement. This goes to show that when companies make miscalculations and fail to implement ethical codes, they are the ones who pay for it through expensive law suits and tarnished images. Business ethics Companies need to have specified code of conduct and ethics principles that will guide their day to day practices. Shell as a company has well written down rules that assist employees in sticking to the company's goals and principles. Some of these codes of conduct include; honesty, trust and integrity. While stakeholders and employees may be well aware of rules, abiding by them is another issue altogether. (Zenobank, 2008) The enormity of this matter came to fore during the 2004 business ethics disaster; at that time, the company announced that twenty percent of all the oil reserves that it claims to have a hold to were overestimated. The revelation of such a matter brought shock waves within the Oil trading sector and even resulted in the company's poor performance. In response to this issue, the company changed its leadership structures. This business dismissed its managing Director - Sir Philip Watts and also changed their management structures. Besides this, the company also responded by providing opportunities for whistle blowers to report any irregularities through an official company website. (Beasnat & Cummins, 2005) BP also has a valid code of ethics and its company purports to a sound code of conduct. However, much like its counterpart Shell, the company seems to have fallen short of these high expectations. An example of how the company did this was when it hired an expensive public relations manager to create an Image of an