Computer Science. The English Language Perspective - Беликова (1176925), страница 7
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Each transaction between the CPU and memory iscalled a bus cycle. The number of data bits a CPU is able totransfer during a single bus cycle affects a computer’sperformance.One distinguishing characteristic of RAM is that it is possibleboth to read data from the memory and to write new data intothe memory easily and rapidly.
Both the reading and writingare accomplished through the use of electrical signals.The other distinguishing characteristic of RAM is that it isvolatile. A RAM must be provided with a constant powersupply. If the power is interrupted, then the data is lost.The two traditional forms of RAM used in computers areDRAM (dynamic RAM) and SRAM (static RAM). A dynamicmemory cell is simpler and smaller than a static memory cell.Thus, a DRAM is more dense (smaller cells = more cells perunit area) and less expensive than a corresponding SRAM.DRAMs tend to be favored for large memory requirements.SRAMs are generally somewhat faster than DRAMs.
Because ofthese relative characteristics, a static RAM is used for cachememory (an intermediate layer of memory that is smaller butfaster, and can hold portions of programs that are likely to beused again shortly), and a dynamic RAM is used for mainmemory.39Input/Output UnitsAll of the computing power in the world wouldn’t be useful ifwe couldn’t input values into the calculations from outside orreport to the outside the results of the calculations. Input andoutput units are the channels through which the computercommunicates with the outside world.An input unit is a device through which data and programsfrom the outside world are entered into the computer.
The firstinput units interpreted holes punched on paper tape or cards.Modern input devices include: the mouse, keyboard, touchscreen monitor, scanner, track pad, microphone, joystick, andweb camera.An output unit is a device through which results stored in thecomputer memory are made available to the outside world.
Themost common output devices are printers, video displayterminals, speakers, and plotters.System interconnectionThe memory, the peripherals and the CPU communicate witheach other via the bus, which carries data around and allows,for example, data to be transferred from disc into mainmemory.
The bus consists of a set of physical wires plus aprotocol (of which there are many, for example, PCI, ISA, IDEetc) that is implemented by the bus controller that determineswhich subsystem can communicate (depending on priorities,previous access history, and other factors). In all cases, only onepiece of data can be on the bus at any time.A bus that connects major computer components (processor,memory, I/O) is called a system bus. The most commoncomputer interconnection structures are based on the use of oneor more system buses.In a personal computer, the components in a von Neumannmachine reside physically in a printed circuit board calledmotherboard. The motherboard also has connections forattaching other devices to the bus such as a mouse, a keyboard,or additional storage device.40Notes:RAM (Random Access Memory) - оперативная память,оперативное запоминающее устройство, ОЗУPCI (Peripheral Connect [Component] Interconnect) межсоединение периферийных компонентов, шина PCIISA (Industry Standard Architecture) - архитектура шиныпромышленного стандарта, шина ISAIDE (Integrated Drive Electronics) - встроенный интерфейснакопителей, интерфейс IDEAssignments1.
Translate the sentences from the text into Russian payingattention to the underlined words and phrases:1. The more data it is possible to have available in theRAM, the faster the PC will run.2. A static RAM is used for cache memory (anintermediate layer of memory that is smaller but faster,and can hold portions of programs that are likely to beused again shortly).3. All of the computing power in the world wouldn’t beuseful if we couldn’t input values into the calculationsfrom the outside or report to the outside the results ofthe calculations.4.
The first input units interpreted holes punched on papertape or cards.5. In all cases, only one piece of data can be on the bus atany time.412. Answer the following questions:1. Name the components of the computer.2. What are the major structural components of the CPU?3.
Why is the ALU considered to be the essence of acomputer?4. What kind of information do registers store?5. What is the control unit responsible for?6. What kind of information is stored in the main memory?7. How is the main memory connected to the CPU?8. Name the distinguishing characteristics of RAM.9. How do the memory, the CPU, and the peripheralscommunicate with each other?3. Translate into English:а.) Шины, как известно, используются для передачиданных от центрального процессора к другим устройствамперсонального компьютера.
Для того, чтобы согласоватьпередачу данных к другим компонентам, работающих насвоей частоте, используется чипсет – набор контроллеров,конструктивно объединенных в Северный и Южныймосты. Северный мост отвечает за обмен информацией соперативной памятью и видеосистемой. Южный – зафункционирование других устройств, подключаемыхчерез соответствующие разъемы – жесткие диски,оптические накопители, а также устройств, находящихся наматеринской плате (встроенная аудиосистема, сетевоеустройство и др.), и для внешних устройств (клавиатура,мышь и т.д.).б.) Кэш-память – это высокоскоростнаяпамятьпроизвольногодоступа,используемаяпроцессоромкомпьютера для временного хранения информации.
Онаувеличивает производительность, поскольку хранитнаиболее часто используемые данные « ближе» кпроцессору, откуда их можно быстрее получить. Хотя42оперативная память намного быстрее диска, тем не менее иона не успевает за потребностями процессора. Поэтомуданные, которые требуются часто, переносятся наследующий уровень быстрой памяти, называемой кэшпамятью второго уровня.
Она может располагаться наотдельной высокоскоростной микросхеме статическойпамяти (SRAM), установленной в непосредственнойблизости от процессора (в новых процессорах кэш-памятьвторого уровня интегрирована непосредственно вмикросхему процессора).На более высоком уровне информация, используемаячаще всего, хранится в специальной секции процессора,называемой кэш-памятью первого уровня. Это самаябыстрая память.4. Give the summary of the text using the key terms.SECONDARY STORAGE DEVICESRead the following words and word combinations and usethem for understanding and translation of the text:to install- устанавливатьstorage device- запоминающее устройство, накопительto back up – создавать резервную копиюto discard - отбрасывать, отвергатьtime-consuming - трудоемкий, отнимающий многовремениto spin - вращаться, крутитьсяto retrieve - находить, извлекатьto vary - меняться.
варьироватьcapable of - способный кconsistent – совместимый, последовательныйto time information - распределять (синхронизировать)информацию43hence - отсюда, следовательноhigh-definition - высокая четкость, с высокимразрешениемto retain - coхранять, удерживатьnon-volatile- энергонезависимыйnetwork switch - сетевое переключениеparallel processing system - система параллельнойобработкиpipelining - конвейерная обработкаto hand over - передаватьto update - обновлятьto range from…to - варьировать, изменятьсяSince most of main memory is volatile and limited, it isessential that there be other types of storage devices whereprograms and data can be stored when they are no longer beingprocessed or the machine is not turned on. These other types ofstorage devices (other than main memory) are called secondaryor auxiliary storage devices.Secondary storage devices can be installed within the computerbox at the factory or added later as needed.
Because thesestorage devices can store large quantities of data they are alsoknown as mass storage devices.Magnetic TapeThe first truly mass auxiliary storage device was the magnetictape drive. A magnetic tape drive is most often used to back upthe data on a disk in case the disk is ever damaged. Tapes comein several varieties, from small streaming-tape cartridges tolarge reel-to-reel models.Tape drives have one serious drawback.
In order to access datain the middle of the tape, all the data before the one you wantmust be accessed and discarded. Although the modernstreaming-tape systems have the capability of skipping oversegments of tape, the tape must physically move through the44read/write heads. Any physical movement of the type is timeconsuming.Magnetic DisksA disk drive is a cross between a compact disk player and atape recorder. A read/write head travels across a spinningmagnetic disk, retrieving or recording data. Like a compactdisk, the heads travel directly to the information desired, and atape, the information is stored magnetically.Disks come in several varieties, but they all use a thin diskmade of magnetic material. The surface of each disk is logicallyorganized into tracks and sectors. Tracks are concentric circlesaround the surface of the disk.
Each track is divided intosectors. Each sector holds a block of information as acontinuous sequence of bits. Although tracks nearer the centerlook smaller, each track has the same number of sectors, andeach sector has the same number of bits. The blocks of datanearer the center are just more densely packed. The actualnumber of tracks per surface and the number of sectors pertrack vary, but 512 bytes and 1024 bytes are common.
Thelocation of the tracks and sectors are marked magneticallywhen a disk is formatted; they are not physically part of thedisk.There is a variety of disks. One classification of disks is hardversus floppy. These terms refer to the flexibility of the diskitself. The original floppy disk, introduced in the 1970s, was 8”in diameter and very floppy.
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