CENTRAL PROCESSING UNIT
Иностранные языки, филология и лингвистика
UNIT 4. CENTRAL PROCESSING UNIT I. Practise reading the following words: execute fundamental circuit tolerances miniaturization standardization automobile configure advent eventually significantly wiring contents architecture primarily discrete differentiate failure whereas desired retrieve deterring issue register directly cycle entire simultaneously access monolithic separate. II. Before reading the text try to answer these questions: 1. What i...
UNIT 4. CENTRAL PROCESSING UNIT
I. Practise reading the following words:
execute, fundamental, circuit, tolerances, miniaturization, standardization, automobile, configure, advent, eventually, significantly, wiring, contents, architecture, primarily, discrete, differentiate, failure, whereas, desired, retrieve, deterring, issue, register, directly, cycle, entire, simultaneously, access, monolithic, separate.
II. Before reading the text try to answer these questions:
1. What is a central processing unit?
2. What is the main function of the CPU?
3. What are the advantages in making computers as small as possible?
III. Read and translate the following text.
Central processing unit
A central processing unit (CPU) is a logic machine that can execute computer programs. This definition can be applied to many computers that existed before the term «CPU» came into widespread usage. The form, design and implementation of CPUs have been changed dramatically since the earliest examples, but their fundamental operation has remained the same.
Early CPUs were custom-designed as a part of a larger computer. The integrated circuit (IC) has allowed increasingly complex CPUs to be designed and manufactured. Both the miniaturization and standardization of CPUs have increased the presence of these digital devices in modern life. Modern microprocessors appear in a wide range of things from automobiles to cell phones and children's toys.
On June 30, 1945, mathematician John von Neumann published the paper «First Draft of a Report on the EDVAC» in which he outlined the design of a stored-program computer that would eventually be completed in August 1949. EDVAC was designed to perform a certain number of instructions or operations of various types. With von Neumann's design, the programs that EDVAC ran could be changed by substituting the contents of the computer's memory.
The so-called Harvard architecture of the Harvard Mark I, which was completed before EDVAC, also utilized a stored-program design by using punched paper tape rather than electronic memory. The key difference between the von Neumann and Harvard architectures is that the latter separates the storage and treatment of instructions and data, while the former uses the same memory space for both. Most modern CPUs have von Neumanns design, but elements of the Harvard architecture also exist.
The general task of most CPUs is to execute a sequence of instructions called a program which is represented by a series of numbers stored in the computer memory. There are four steps that nearly all von Neumann CPUs use in their operation: fetch, decode, execute and writeback.
The first step, fetch, involves retrieving an instruction from program memory. The location in program memory is determined by a program counter (PC), which keeps track of the next instruction to be performed in the main memory. The instruction that the CPU fetches from memory is used to determine what the CPU must perform.
In the decode step, the instruction is broken up into parts that have significance to the CPU. The CPU's instruction set architecture (ISA) defines the way numerical instruction value is interpreted. Often, one group of numbers in the instruction (called the opcode) indicates which operation to perform. In older designs the portions of the CPU responsible for instruction decoding were unchangeable hardware devices. However, in more complicated CPUs and ISAs, a microprogram is often used to assist in translating instructions into various configuration signals for the CPU. This microprogram is sometimes rewritable so that it can be modified to change the way the CPU decodes instructions even after it has been manufactured.
After the fetch and decode steps, the execute step is performed. During this step, various portions of the CPU are connected so they can perform the desired operation. If, for instance, an addition operation is requested, an arithmetic logic unit (ALU) will be connected to a set of inputs and a set of outputs. The inputs provide the numbers to be added, and the outputs will contain the final sum. The ALU contains the circuitry to perform simple arithmetic and logical operations. If the addition operation produces a result too large for the CPU to handle, an arithmetic overflow flag in a flags register may also be set.
The final step, writeback, simply «writes back» the results of the execute step to some form of memory. Very often the results are written to some internal CPU register for quick access by subsequent instructions. In other cases results may be written to slower, but cheaper and larger, main memory. Many instructions will also change the state of digits in a «flags» register. These flags can be used to influence how a program behaves, since they often indicate the outcome of various operations. The flag could then be used by a jump instruction to determine program flow.
A multi-core CPU combines two or more independent cores into a single package composed of a single integrated circuit, called a die and implements multiprocessing in a single physical package. A processor with all cores on a single die is called a monolithic processor. Cores in a multi-core device may share a single coherent cache at the highest on-device cache level (e.g., L2 for the Intel Core 2) or may have separate caches (e.g., current AMD dual-core processors). Each «core» independently implements optimizations such as superscalar execution, pipelining and multithreading. The most commercially significant multi-core processors are used in computers (primarily from Intel & AMD) and game consoles (e.g., the Cell processor in the PS3).
IV. Answer the following questions:
1. What is a definition of a central processing unit?
2. What is the impact of using integrated circuits in computer technology?
3. What is the John von Neumann famous for?
4. What architectures are there in modern computers?
5. What steps do von Neumann CPUs perform in their operation?
6. What operations are performed by the arithmetic logic unit?
7. What is a multi-core CPU?
8. What companies' multi-core CPUs are the most commercially significant?
V. Decide whether the following statements are true or false. It they are false, correct them.
1. On June 30, 1945, John von Neumann published his paper «First Draft of a Report on the EDVAC».
2. After the fetch and decode steps, writeback is performed.
3. CPU performs four operations: fetch, encode, decode and writeback.
4. CPU is arithmetic-logic machine that can execute computer programs.
5. A microprogram cannot be modified to change the way the CPU decodes instructions.
VI. Write the plural form of the following nouns:
core, memory, system, datum, megabyte, information, frequency, machine, device, product, copy, medium, capacity, minute, role, input, drawing.
VII. Arrange the words in the correct order to make sentences:
1. computer, The, or, how, processes, fast, CPU, information, controls, the, data.
2. faster, the, will, higher, the, computer, of, The, speed, run, the, the CPU.
3. needs, on, a, Watching, the, modem, a, CPU, movies, and, faster, Internet.
4. the, memory, called, except, and, are, All, CPU, working, hardware, peripherals, the.
5. are, touch, a, monitor, you, or, hardware, such, of, The, CPU, can, parts, the, as, computer, the.
VIII. Match each term with its definition:
1. fetch a) the state of being connected together
2. input b) a device that connects a computer to the Internet
3. retrieve c) a drawing or plan that shows how something new will be made and how it will work, etc.
4. dual d) to go and get the next instruction or piece of data from memory
5. connection e) to manage or use something; to do business
6. custom f) to come into view so that you can see somebody or something
7. modem g) the act of putting information into a computer
8. operate h) having or using two parts or aspects
9. design i) to find the information that has been stored
10. appear j) a way of behaving which a particular group or society has had for a long time
IX. What do the following abbreviations stand for?
CPU, IC, ALU, ISA, PC, ENIAC, EDVAC, AMD.
X. Divide the text into logical parts and find topical sentences in each part. Write out of the text words and word combinations for describing four steps of the CPU operation.
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