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2129710142200313CSE312 Amir Adel Salah.Pdf استمارة جقييم الزسائل البحثيت ملقزر دراس ي اوﻻ : بياهاث جمل بمعزفت الطالب اسم الطالبـــــــــــ :أم ري عادل صﻻح عبد العظيم كلية : الهندســــه القسم: الحاسبات و النظم الفرقة/المستوى : الثالثة الشعبة : اسم المقرر :بنية الحاسب كود المقرر : CSE312 استاذ المقرر : د.طارق مراد جمعة ر ال رييد اﻻلكيون [email protected] : للطالب عنوان الرسالة البحثية : Modern Computers Memory ثاهيا: بياهاث جمل بمعزفت لجىت املمتحىيين هل الزسالت البحثيت املقدمت متشابت جشئيا او كليا ☐ وعم ☐ ﻻ فى حالت الاجابت بىعم ﻻ يتم جقييم املشزوع البحثى ويعتبر غير مجاس جقييم املشزوع البحثى م عىاصز التقييم الوسن التقييم اليسبى 1 الشكل العام للزسالت البحثيت 2 جحقق املتطلباث العلميت املطلوبت 3 يذكز املزاجع واملصادر العلميت 4 الصياغت اللغويت واسلوب الكتابت جيد هتيجت التقييم النهائى 100/ ☐ هاجح ☐ راسب جوقيع لجىت التقييم 1. .2 .3 .4 .5 جزفق هذه الاستمارة كغﻻف للمشزوع البحثى بعد استكمال البياهاث بمعزفت الطالب وعلى ان ﻻ جشيد عً صفحت واحدة Computers Memory Introduction At the beginning of the age of technology , A new term name called Memory has appeared .The memory is the most important thing in Computer . it is the main item which is responsible for data storage. The memories were designed by different ways and through multiple stages. At the beginning of memory manufacturing, the memory was produced by vacuum tubes from 1946 to 1959 .Vacuum tubes were basic components which was used to make the first generation of memories . Also the vacuum tubes used to make circuitry of CPU (Central Processing unit).In this generation ,the basic programming language was machine code which used in computers used vacuum tubes in the memory. There were many types that were made the same way as punch cards , paper tape , and magnetic tape which used as input and output devices . But the first time that the vacuum tubes were used there were many problems and defects appeared such like generation a lot of heat and consumption a lot of memory . This reduced the memory life and was not good in terms of performance . As it led to a very slow transfer and reception of information.The computers used this type of memory were like ENIAC , EDVAC,UNIVAC,IBM 701 and IBM 650.Then they discovered a new type of material used to make the memory called ferrite magnet rings. The memory which produced from this type called Magnetic core memory . So it was designed by hard material but in shape of rings . It was working in the principle of current . Sending current through every wire causes the memory core writes one or zero .the first generation of this type was in 1947 and it was attributed to Fredrick Viehe .Magnetic core memory used at least 20 years from 1950 to 1970. Memory has experienced great development over the years .But now , we are dealing with Semiconductor Memories such like Ram and Rom .In the 1960, they started to produce the first semiconductor memory from bipolar transistors .In 1961 United State Air Force required from Texas instruments to support them by bipolar semiconductor memory but the first model was out in 1965 called SP95 and introduced by IBM . Although this type appeared , it was failing to replace magnetic core memory because bipolar circuits are large and expensive. But in main topic the types of memory will be discussed from all sides. Simply ,the memory is a device to store data or program (sequences of instructions). So the computers get these data as binary code . Each binary digit is being stored in memory to represent 0 and 1.so now the computer uses many types of memory .Although the hard drive and ram are memory .It is very important that they are classified into Ram as memory or primary memory and hard drive as storage or secondary storage . As we will look at all types of memory used in the computer and the dates of use or development of each type in that research. Topic The memory is not only storage device , it is sometimes used to fast the operation of data transfer . as example, if the computer’s CPU needs to access data from hard drive ,the operation will take more time and become very slowly . this makes the CPU in Idle state. Therefore, another type of memory is used like RAM or different levels of cache to make the process more fast And take all the benefit and time from the CPU. In computer, we can classify the memory into four categories: CPU registers Cache Memory Primary memory / Main memory Secondary Memory / Mass storage o Virtual memory CPU registers In CPU, The registers are a type of a computer memory . it is needed to a hold data , information and instructions which are treating with CPU temporirly.it is also needed to hold the memory location which is required to calculate the addresses of the next instructions after completing the current instructions from CPU . the current instructions go to exit state after full process from CPU . so , the CPU register needs to know the address which was used from CPU to get and calculate the location of the next instruction which will go in execution state. These registers are PC (Program counter): Increase the location of the last address and store the new the address of the next instructions in RAM. Memory address register : hold the addresses of next instructions from main memory. Memory data register: get only data from main memory to be executed by CPU. Current instruction register : hold the instructions which is decoded and executed . Accumulator : it is responsible for calculation processes which done in CPU and its results . IR (Interrupt register): control the processes when interrupt occurs due to input/output devices or execution time is ended. Cache Memory In the past, computer systems was treating with hard disk as a device storage and mean to transport data to CPU but the problem is the time . the process is very slowly .then they tried to make a small memory with high cost to access the data from CPU directly with high speed.so , the cache memory is more rapid than hard disk and RAM. In Reality, Cache memory helps the computer’s CPU to do the operations rapidly .It holds the instructions from Main memory or ram and makes the CPU to fetch it. This process prevents the CPU from waiting when needing to get new instruction from The main memory. Cache memory is locating very nearly from CPU chip itself And the link between the two parties are the data buses.so we say that the cache memory increases the performance of the CPU. The result is that a very small amount of cache memory can result in a significant increase in the computer's performance .Until now the cache memory is used to reduce the slow and performance bottlenecks between the RAM and CPU. Sometimes we ask why we can not use more Other pieces of the SRAM. SRAM is fast but more expensive .so , it is preferred to use cache memory which has more speed and less capacity. but the CPU is dealing with 2 types of cache the primary cache and the secondary cache. Primary cache represents into the piece which locates on the same chip of CPU. And secondary cache represents into the part which is away from CPU and not in the same chip but it locates on a separate chip. Now, the developers seek to develop the modern computers so, they try to get more than one piece of cache. But every piece has a special size and speed .These are known as cache levels. Primary memory Sometimes , it is called Main memory or Internal Memory .The primary memory is the memory which connects the CPU Directly with buses . it is formed from two important parts RAM and ROM that store system programs. its manufacturing by using integrated circuits or semiconductor device. Its advantages are that the size is small , also it is more speed than secondary memory but it is more expensive from secondary memory. When you turn on the computer, Generally CPU searches for essential codes in RAM to get it. Otherwise, it goes to ROM. Yes, they both chips collectively called primary memory in a computer system. So we will discuss the ROM and RAM Rom Rom is read only memory and semiconductor memory that can only read data of the system. At the first time when the ROM is programmed from the company , No one can change or delete anything from it . It is usually used in computer or other electronic devices, and even if the power is turned off, the data will not disappear. Rom is nonvolatile memory so it is used in computer and some electronic devices. But, we cannot use it as a primary storage because if we need to get 1 terra as a internal size, it will increase the cost. Also the non-volatile memories have lower performance, or have a limited lifetime compared to volatile random access memories. The ROM is not only one type but There are more one type to ROM. Always the developers try to get their best to reach to the best performance of memory. Types of ROM: MROM (Mask Read Only Memory):it was manufactured to be very fast. Also it is expensive ROM which is hard wired device that contains a pre-programmed set of data or instructions. PROM (Programmable Read Only Memory): In this type , the user can write only one time in chip . The obvious difference between ROM and PROM , The ROM is written in manufacturing Process and no one can write in it but PROM is made from blank Memory.
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