Memory Units And Memory Hierarchy

Memory Units And Memory Hierarchy Memory organisation is combination of several memory devices efficiently. Memory devices are combined and organised based on their characteristic such as access time, speed, storage capacity, physical size and cost per byte. Memory devices organised in such a way that computer system should operate at highest speed, provide bulky storage capacity, smaller in size and less in a cost. Memory organisation uses primary memory devices and secondary memory devices. 3.2 Memory Unit Memory unit is storage unit of the computer system. It stores content such as instructions (codes) and data for temporary or permanent purpose. It is used to stores content and to retrieves the content when needed by CPU or user. Memory unit includes two types of memory: primary (main) and secondary. Instruction or data given by input devices is first getting stored in the primary memory. Further users saves processed (executed) data in the secondary memory. Primary memory is volatile (temporary). It is faster than secondary memory. It includes RAM and ROM. It is directly accessible by CPU. Secondary memory is non-volatile (permanent). It includes several secondary storage devices such as Hard Disk Drive (HDD), Floppy Disk Drive (FDD), CDROM, and DVD and so on. Figure 3.1 shows memory unit and communication line with other units. Note: Volatile memory loses its content when computer loses power. In non-volatile memory power loss of computer does not affects content. Input Unit Process Unit Output Unit Primary Memory Secondary Memory Memory Unit 3.3 Memory hierarchy Memory organisation includes various memory devices. These devises are structured in a hierarchy based on the characteristics of memory devices. Memory hierarchy explains the sequence of accessing memory device while processing, in the computer system. Memory is structured in the hierarchy in such a way that computer system should give excellent performance. Figure 3.2 shows Memory hierarchy. Hierarchy is made on the basis of characteristics of memory, they are listed as follow: Access Time Time taken by memory to read or write data. It is measured in milliseconds (ms) or in nanoseconds (ns). Memory size It is amount of memory. Measured in KB, MB, GB or TB. Cost per byte It is cost required to access per byte. Transfer bandwidth It is speed of the memory. It measured in MHz, GHz. Unit of transfer Data transfer rate. Measured in Kbps, Mbps or Gbps. Increasing speed and cost per bit dcreeasing sisize Registers in CPU Level one cache Level two cache Main memory Virtual Memory Increasing Size, decreasing speed and cost capacity Secondary Storage devices Figure 3.2 Memory Hierarchy Memory hierarchy includes CPU registers on the top. Register provides fastest data access and it is one of the most expensive memory location. Second and third levels are level-1 and level-2 cache respectively. The level one cache is small in size (4 KB to 32 KB) though much larger than register. It is fixed on CPU chip so user can not expand. The level-2 cache is present on some CPUs only. It is much larger than level-1 cache. User can not expand it as it is fixed on CPU chip but it is cheaper than level-1 cache. Virtual memory is part of disk drive, which simulates to Random Access Memory (RAM). Disk drives are less expensive; so cost per bit is significantly less. Secondary storage devices are such as Hard Disk Drive (HDD), Floppy Disk Drive (FDD), Compact Disk Read Only Memory (CDROM), Digital Versatile Disk (DVD) and tape drives. It is bit slower. 3.4 Memory types Basic purpose of memory is to store content. Still memory is available in different types. Basic type of memory is primary memory and secondary memory. Types are made based on memory characteristics and its role in the computer system. Primary memory is the first memory used by CPU, so it should be faster and easily accessible. To make primary memory as per the requirement, memory organisation includes RAM and ROM as primary memory. The main use of secondary memory is use to store users data permanently. Speed of secondary memory can be compromised, but storage capacity should be excellent. So memory organisation includes HDD, FDD, and CDROM and so on as a secondary memory. Figure 3.2 shows types of memory. 3.4.1 Primary Memory Primary memory is access directly by CPU. Primary divided in to two types RAM and ROM. Primary memory should be faster and easily accessible. RAM RAM is a primary memory used in the computer. RAM is the main memory of the computer system. It is volatile since its content is accessible only as long as the computer is ON. The content of RAM is cleared as soon as computer is powered OFF. It is at third place in the memory hierarchy. Operating system, application program and running data are loaded in the RAM. CPU directly accesses the RAM. Types of RAM are as follows: Static Random Access Memory (SRAM) SRAM is made with several transistors, usually four to six, for each memory cell. It does not require refresh time as capacitors are not used. It is much faster and costlier than DRAM. Computer system use SRAM as cache memory. DRAM (Dynamic Random Access Memory) It has memory cells with a paired transistor; it uses capacitor, as capacitors slowly leaks with as they stared discharging, so need periodic refresh. It is slower and chippers than SRAM. It is much denser (stores many bits per chip). It requires less power and generates less heat as compared to the SRAM. DRAM is available in several forms such as SDRAM, then DDRAM to RDRAM. Read Only Memory (ROM) ROM is non-volatile primary memory. Data written on ROM can not delete or overwrite. Data is burned on the ROM as firmware. ROM memory is used in the computer system to write firmware for example BIOS program. Types of ROM are as follows: Programmable read-only memory (PROM) This type of memory is one time written memory. Once program is written can not be change. Erasable programmable read-only memory (EPROM) Data written on EPROM can be erased. Ultraviolet is used to erase the data written on PROM. Electrically erasable programmable read-only memory (EEPROM) It is same as EPROM but to erase data entirely it requires electrical signal. So not require to remove from computer. Data can be erased or over written it the computer itself. 3.4.2 Secondary Memory A secondary memory is non-volatile. Secondary memory used to save users data permanently. Devices used as secondary memory are HDD, FDD, CD, DVD, Tape drives and so on. Secondary memory is at sixth place in the memory hierarchy. Devices used as secondary memory are listed as follows: Floppy Disk Drives (FDD) Used as magnetic, portable memory device. It stores maximum 1.44 MB data. Earlier it used to transfer data among computer systems. Hard Disk Drives (HDD) HDD is fixed, magnetic memory device. It is vital in the computer system because Operating System and users data is saved on the HDD. Storage capacity of HDD is vendor specific. CDROM and DVDROM Are optical memory units used for transferring data and programs among the computers. CDs are available in the size 650MB, DVDs are available up to 4 GB in a size. Tape drives Are usually used for data backup purpose. 3.6 Cache Memory The cache is small amount of memory with high speed. Cache memory keeps data and code (introductions) that are used by CPU often. Use of cache memory reduced the waiting time of CPU that makes CPU more effective. SRAM is used to create cache memory. SRAM does not required refresh as it does not use capacitors as DRAM, it is 10 times faster than DRAM. Cache is of two types Level-1 that is placed ion the CPU. Level 2 cache is optional some processors have this type of memory that is some time placed inside the CPU or placed near by CPU. To execute next instruction, CPU first check cache memory for the same instruction if that instruction is not available then it goes further. Note: DRAM is made up of capacitors which need constant refreshing to preserve data. SRAM uses flip-flop circuit that does not require refresh. 3.6.1 Cache line replacement Algorithms While a new line is loaded in the cache, one of the existing lines must be replaced. Direct mapped cache, same block from line is removed take place for new one. In associative cache, it can search for another place. Four of the most common line replacement algorithms are as follows: LRU (Lease Recently Used) the cache line that was last referenced in the most distance past is replaced. FIFO (First In First Out) the cache line from the set that was loaded in the most distant past is replaced. LFU ( Least Frequently Used) the cache line that has been referenced the times is replaced. Random a randomly selected line from cache is replaced. Note: The most commonly used algorithm is LRU. Cache Terminology Cache use few terminology for operation are as follows: Hit A cache access finds data the cache memory Miss A cache access does not find data or instruction, forcing access to next memory down in memory hierarchy. Miss ratio Percent of misses to data compared to all accesses. Hit access time Number of clocks to return a cache hit Miss penalty Number of clocks to process a cache miss. Virtual Memory Operating system enables a process through which space of hard disk drive can be simulate to RAM. The HDD space used as RAM is known a Virtual Memory. As cost per byte of HDD is less, so virtual memory is beneficial to run many large programs that need more memory. Access time of RAM is in nanoseconds but virtual memory gives access time in milliseconds. It is much slower than RAM. Figure 5.1 shows operation of virtual memory. Virtual memory uses paging and segmentation terminologies. Terms used by paging are as follows: Virtual address- Address used by application program from virtual memory. It is composed of page number and page offset. Physical address Address of physical memory. Page virtual space divided into fixed-size pages. Frame Physical memory divided into fixed frames size. MMU Memory Management Unit (MMU) used to map virtual address to physical address. Page table Each process has its own page table. Each page table entry contains the frame number of the corresponding page in main memory Figure 3.4 Virtual memory operations 3.8 Chapter Review Questions Which of the following is primary volatile memory? (A) RAM (C) ROM (B) HDD (D) FDD Ans: A Which among the following are magnetic storage devices? (A) HDD (C) FDD (B) CDROM (D) DVDROM Ans: A and C Maximum storage capacity FDD is - (A) 2GB (C) 2.44 MB (B) 1.44MB (D) None of these Ans: B A  ­Ã‚ ­Ã‚ ­____ is used as cache memory in the computer system. (A) SRAM (C) DRAM (B) SDRAM (D) ROM Ans: A Which of the following is primary non-volatile memory? (A) Cache (C) ROM (B) Virtual (D) None of these Ans: C Which of the following ROMs content can be deleted using ultraviolet? (A) PROM (C) EPROM (B) ROM (D) EEPROM Ans: C Virtual memory is concept of (A) Using HDD space as RAM (C) Using FDD space as a RAM (B) Logical based (D) Protocol based Ans: A 8. In the memory hierarchy which memory is at first level? (A) Register (C) L1 cache (B) L2 cache (D) None of these Ans: A 9. Which memory takes second place in the memory hierarchy? (A) L1 cache (C) L2 cache (B) ROM (D) HDD Ans: B 10. MMU stands for (A) Memory Mixture unit (C) Memory Management Unit (B) Memory measurement Unit (D) None of these Ans: C 3.8.1 Answers 1. A 2. A and C 3. B 4. A 5. C 6. C 7. A 8. A 9. B 10. C Summary In the chapter, Memory Organisation, you learnt about: Different memory units and its types. Memory hierarchy based on memory characteristics. Cache and its replacement algorithm. Virtual memory and paging.

Hemingways the Old Man And The Sea: An Analysis :: essays research papers

Hemingway's "The Old Man and the Sea": An Analysis Everyone has an arch enemy. Batman had the Joker, Superman had Lex Luthor. But without their enemies, they would be unimportant, just like anyone else. One could say that they needed their enemies, that their enemies were almost friends. Similarly, The Old Man and the Sea, by Ernest Hemingway, is a love story about the relationship developed over the years between a man and his lifelong friend and foe, the sea. Within the following paragraphs, it will be proven that the man needed the sea, that the two respected each other, and were very close. The old man respected the sea, unlike some of the younger, richer fishermen. They referred to the sea as a man. "...spoke of her as el mar which is masculine." (p.30) This was considered improper to the older fishermen, as it was spoken of like a place or a contestant. The old man always referred to the sea as a female, like a mother. "He always thought of the sea as la mar which is what people call her in Spanish when they love her." (p.29) He saw the sea as a woman, a woman that gave or withheld favors. She was unpredictable beacuse "The moon affects her as it does a woman." (p.30) The sea was like a second home for the man, who fished every day. La mar provided the man with food, a living, an enemy, and a friend. When he was out on the sea fishing, he was at home. The sea, la mar, was like his mother. The fish in the ocean were like his brothers and sisters. When he heard the dolphins playing in the night he thought, "They are good...they are our brothers like the flying fish." (p.48) He had almost reeled the giant marlin in when he realized what he was doing. "You are killing me, fish. But you have a right to. Never have I seen a greater, or more beautiful...thing than you, brother." (p.92) Even as he ate the fish that he would catch, or as he killed scavengers trying to get the marlin, he was apologizing or talking to his "family". The old man saw the sea as a person, as a woman, and the fish were people, also. Thinking that way, he kept an open dialogue with his surroundings. Throughout the several days in which he tried to catch the marlin, he constantly spoke to it. He had just eaten a fish to get his strength back when he said, "How do you feel, fish?

Audience Analysis Essay

â€Å"Audience analysis gives you the tools you need to shape your product and your message† (Locker & Kienzler, 2008, p. 41). When presenting the company’s quarterly sales information it is important to evaluate the audience so that you can tailor the message to their needs. Considering the characteristics of the audience; the more you know about the audience, the more you can focus your presentation on what they need to know. You will also need to determine which communication channel is the most effective to present this information. It is almost important to understand the diversity of the audience so that you aren’t focusing on one group of people. If you spend the time analyzing your audience you can ensure that your sales presentation is effective. The more you know and understand your audience the better your message will be; you can start by identifying the characteristics of your audience. According to Locker and Kienzler (2008), the demographic characteristics such as age, sex, race, religion, education level, and income may be relevant when analyzing the audience. Because the sales presentation is for the stakeholders of the company, particularly managers, sales, and the customers, the demographics of the audience may be irrelevant for this case. When analyzing the stakeholders for this presentation, it is important to evaluate what they have in common and what is important to them. For example, stakeholders have a stake in the company so they want to see the company succeed; the sales data should be detailed enough to see the true performance of the company. Performing an audience analysis can be simplified by focusing on who they are, what their needs and expectations are, and how they will use the information. Managers need the sales information to gauge the performance of the company and to help make decisions on the day-to-day operations. The sales staff can use the information to see if they are meeting their sales goals and customers want to know that their suppliers are operating consistently and solid. Knowing the specifics needs you audience needs will help you when you are organizing your information for the presentation. Effective communication is based on selecting the appropriate communication channel to convey your message. Communication channels are the methods that are used to send a message to the audience. These methods can vary in efficiency and speed to the number of people who are reached (Locker & Kienzler, 2008). These messages can be sent through brochures, letters, e-mail messages, telephone conversations, video conferencing, and face-to-face meetings (Communication Channels, 2011). You are currently planning your sales presentation for a face-to-face meeting with the stakeholders. By meeting face-to-face you can combine some of the communication channels for a more effective message. The written part of the message includes presenting the sales information in a PowerPoint that allows you to include detailed information incorporating graphs and charts. You can communicate the information orally providing a narrative that supports your PowerPoint slides. This can be a very effective method of highlighting specific points of the presentation to what the audience needs to capture. Other methods that can be used effectively in this scenario are a video conference or a conference call combined with Net meeting in order for everyone to access the PowerPoint during the meeting. Emailing this type of information is fast and efficient, but it would be ineffective. There is too much information that could get overlooked and misinterpreted regardless of how much effort you put into the audience analysis. Email channels are more appropriate for routine communication such as day-to-day activities. Selecting the proper channel can contribute to the success of the message. When preparing your presentation it is important to take into consideration the diversity of the audience. Living in a multicultural society it is important to recognize and be sensitive toward the different cultures and ethnicities of people. In addition you should understand the organizational culture. Organizational culture is a set of values and attitudes that can change from company to company. It can be an important part of delivering a successful sales presentation by understanding the culture of the company. In the sales meeting with the stakeholders you have a diverse audience of internal company managers and sales staff and you have external customers. You need to take this into consideration when determining the level of detail that you want to share in the meeting. With the presence of outside people, you may want to be cautious of how much sales information you present in the meeting. Too much information could be damaging; you don’t want your customer to have more information than necessary to get the message across. Analyzing your audience will prepare you for the diversity of your audience. In order to communicate effectively with your audience, you need to understand who they are, what groups they belong to, and what values they hold† (Locker & Kienzler, 2008, p. 41). One way to ensure that you deliver an effective message is to start by performing a thorough audience analysis. Organize the information that you are including the key points that you want to get across. Creating visual aids like graphs and charts that support your ideas can help to keep the attention of your audience. It is also helpful to know your material and have good speaking skills so that you can relay the information without interruption. When meetings run long you can start to lose the attention of your audience; keep the presentation to a time length appropriate to get the message across. Create an interactive meeting and ask questions; this way you will know immediately if the audience is clearly receiving the information that you are presenting. Presenting quarterly sales information requires a little bit more than throwing numbers on a slide and showing them to the managers, sales, and customers present in the meeting. To ensure that you are delivering an effective message put in the extra time to do the research. Evaluate the audience so that you can focus the presentation on what type of data and information that each group of stakeholders need. Prior to scheduling the face-to-face meeting; consider different communication channels to present the sales data, this will help to determine which method is the most effective. Include enough information to ensure that you deliver an effective message that benefits your audience. â€Å"Audience analysis is the first step in any communication process: it gives you the tools you need to shape your product and your message† (Locker & Kienzler, 2008, p. 41).

Business Ethics Essay - 1572 Words

31: Constitutional, Contract, Criminal, Evidence, Property and Tort Law 32: List and explain Nash’s, Drucker’s, Buffet’s, Blanchards and Peale’s comprehensive approach for resolving ethical dilemma Drucker: â€Å"Above all do no harm.† Intentionally making decisions that will not do harm will encourage ethical decision-making. Buffet: front-page-of-the-paper test, it supports critical thinking to envision how the decision may look on the front page of a paper before making the final decision. Blanchard and Peale: three- question test: â€Å"Is it legal?† â€Å"Is it balanced?† and â€Å"How does it make me feel?† Nash: a comprehensive model allows for the incorporation of perspective, alternative views and historical consideration in the decision†¦show more content†¦The terms of the offer and the acceptance 2. Any dates 3. Any oral or telephonic communication 4. The subject matter and whether it’s Article II. Always ask yourself â€Å"is this a contract for the sale of goods?† If it is, Article II applies. If it’s a contract for anything else, common law applies. Normally, it will either be goods, which is Article II, or services. 42:Constitutional law is divided into four broad categories. Please list them 1. Due process 2. Equal protection 3. The privileges and immunities clause of Article IV 4. The First Amendment. We can divide the First Amendment into two subcategories: (a) Free Speech and (b) Freedom of Religion 43: In order to convict one of a crime two elements must exist and concur. What are those two elements? Explain fully with complete details (1) the performance of a prohibited act and (2) a specified state of mind, or intent, on the part of the actor. Additionally, to establish criminal liability, there must be a concurrence (agreement) between the act and the intent. The Criminal Act—In criminal law, a prohibited act is referred to as the actus reus, or guilty act. In some cases an act of omission can be a crime, but only when a person has legal duty to perform the omitted act, such as filing a tax return. State of Mind—A wrongful mental state, mens rea is also typically required to establish criminal liability. The mental state, or intent, is indicated in the applicable statute or law.Show MoreRelatedBusiness Ethics : Ethics And Business943 Words   |  4 Pagesdiscussions in Business is Ethics. Some people believe that the decisions businesses make in interest of the business has no place in ethics and that they are essentially amoral. These businesses believe that their main objective is to simply make a profit and that it does not affect the success of the business. Whereas some businesses believe that they have to take ethics into consideration, in order for their business to be a success. Richard T. 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