استمارة جقييم الزسائل البحثيت ملقزر دراس ي اوال : بياهاث جمل بمعزفت الطالب اسم الطالبـــــــــــ :أم ري عادل صالح 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 االلكيون [email protected] : للطالب عنوان الرسالة البحثية : Modern Memory ثاهيا: بياهاث جمل بمعزفت لجىت املمتحىيين هل الزسالت البحثيت املقدمت متشابت جشئيا او كليا ☐ وعم ☐ ال فى حالت الاجابت بىعم ال 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

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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 . it is the main item which is responsible for 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 ().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 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 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 from bipolar .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 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

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CPU registers

In CPU, The registers are a type of a . 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 . 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. The user should have The PROM burner or PROM programmer to write any data he needs in the blank PROM Chip. The memory can be modified only once in the wake of assembling by "blowing" the , which is an irreversible procedure. EPROM (Erasable Programmable Read Only Memory): EPROM is a special kind of ROMS at which the user can write the data by high voltage also use ultraviolet light for 10 min to expose data .

EEPROM (Electrically Erasable and programmable Read Only Memory): EEPROM is like PROM and EPROM but the only difference is the way of writing data .In this type, the chip should be exposed in electrical charge and the time of this process take from 4 to 10 milliseconds. The EEPROM can be programmed until 10000 times. Also, The user can choose any location to program and erase one byte instead of entire chip. The flexibility of reprogramming process is good but the process is slow.

FM () is a modern type of EEPROM, the new designs of flash memory have high endurance (nearly 1,000,000 cycles). The user can program the flash memory many times , the process of writing data is more faster than the EEPROM. In 2007, they can make the modern NAND flash memory with storage reaches to 32 Gigabyte.

RAM

RAM is an abbreviation of Random Access Memory. The System can read and write in the RAM unlike ROM which read only memory. The RAM has easy way to access the data and information. After the short time , the user can reach to the data or information when he specifies the address of this data. The RAM is a . It holds the information when the CPU needs that. but it accesses the data when the power is on and CPU works. If the power is turned off, it will lose all information and data. So RAM is temporarily memory.

There are two basic types of RAM :

First type is the SRAM , The static RAM is having the information only when the power is on. It stores the information in heap hope and is more speed than dynamic RAM. It is called “static” because it does not need to be refreshed to save the data being stored. S, why we don’t use only the SRAM instead DRAM ? because it is more expensive and lesser memory capacities.

The second type is DRAM, The dynamic RAM consist of , these capacitors always discharge the energy. So , the DRAM requires always to be refreshed by the power to stay in holding the data stored. If there are any lose in power, the DRAM will lost the information. So it was called “dynamic”.In this way we can classify it as volatile memory. Some advantages of DRAM are the more capacities and low cost. But it is slow in accessing data and requires high power. Secondary memory

Unlike the some types in primary memory, the secondary memory has huge storage. Also it is volatile because it is not losing any data when the power is turned off. The secondary memory is not accessed directly by the CPU. So , the RAM takes the data which accessed from the secondary memory then the process access the data from RAM directly. In normal, the secondary memory is having very low speed but the advantage is that it has more space than the primary memory. So, we always see the computer has one hard drive whose capcity equals 1000 gigabyte but the ram is 4 or 8 or 16 gigabyte.

The most important devices in the secondary memory are the hard disk and CD drive.

The hard drive

A hard drive is the hardware component that used to store the data, the information and the all things which used by the operating system permanently because it is nonvolatile memory. Also, the ram sometimes takes extension from the hard disk. This extension called virtual memory.

The virtual memory is the space from secondary memory specially the hard drive. Then it is addressed by way to become part from the ram. The virtual memory works temporarily not permanently .when the ram runs low, Virtual memory use space called paging file to move the data to this place .sometimes some user faces a problem like that the virtual memory runs low.it means that the more space is needed to be added to ram or the size of paging file needs to be increased.

CD drive

It means a compact disk. It is a digital disk which used to access information or data from the computer. It was developed in 1982 by Philips and sony.

Primary memory Secondary memory

 Fast  Slow

 Expensive  Cheap

 Low capacity  Large capacity

 Data can be accessed directly by  Data is not accessed directly by the the . processor.

History time line for some memories

We know nothing remaining fixed at its state so the memory from the past until now, is under development.

In 1837,the used the punch card as memory. It was the first computer using it. Then in 1932,Gustav Tauschek could develop memory called the .

In 1942, john Atanasoff could test the ABC(Atanasoff berry computer)in which drum memory used.

In1946 by cathode ray tube, freddie Williams could to make a small storing device and called Williams tube. It was having the ability to store 40-128 words. It was the first shape of RAM.

In 1950, the united states received the UNIVAC1101 or ERA1101. It was the first computer could access the data from memory directly. In July 1953 a core memory expansion was added to the ENIAC.

In 1955, Zuse completed Z22 which the first computer used the memory. Also in the same year at march the MIT introduced the first digital computer with magnetic core RAM.

In 1969, intel company released SRAM (bipolar 64 bit) and ROM (bipolar 1024bit). Then in 1970 , intel appeared again with its first DRAM which has the ability to store 1KB.also in 1971 , they could release the EPROM .otherwise , George perlegos with intel released the first EEPROM.

In 1993, Samsung appeared the most important invention which was synchronous DRAM (SDRAM).then DDR RAM (DDR=Double Data Rate) came with sold material.

In 2014, they could develop the DDR RAM to DDR RAM4.

According to hard drive in 2007, they released the first hard drive with storage reaches to 1 terabyte. The last edition was in 2017 , they could release the hard drive with storage reaches to 2 terabyte.

Conclusion

In today’s world of ever growing need of faster and high end computers, so the need for faster and better memory technology is never ending .without memory, no one can save its data and information. so the memory is the second important thing after the CPU.As discussed ,Memory plays a great role in computer systems. There are 3 computer memory types available in standard computer based on their function and physical make up. However ,only the main memory that can be changed or upgraded , the other comes with the system whether it is a processor, ROM or graphics card. If there is one thing needed by every computer owner , it will be a place to store his data.

References

 https://www.webopedia.com/TERM/M/memory.html

 https://techterms.com/definition/memory

 https://www.sciencehq.com/computing-technology/cpu-registers.html

 https://computersciencewiki.org/index.php/Cache_memory

 https://www.tutorialspoint.com/basics_of_computers/basics_of_computers_pri mary_memory.htm

 https://www.atpinc.com/blog/computer-memory-types-dram-ram-module

 http://digitalthinkerhelp.com/computer-memory-primary-secondary-storage- devices/