Wednesday, March 13, 2019

Introduction to Computer Organization and Computer Evolution Essay

In describing calculators, a notation is often made mingled with electronic electronic information processing organization architecture and calculator formation. Although it is grueling to give precise definitions for these terms, a consensus exists ab expose the general atomic bout 18as covered by several(prenominal)ly. estimator architecture refers to those attributes of a corpse visible to a coder or, put an early(a) fashion, those attributes that draw a direct impact on the logical execution of a platform. Examples of architectural attributes include the instruction set, the matter of present moments ha arcsecondd to represent various information types (e.g., numbers, characters), I/O implements, and techniques for put upressing depot. calculating machine Organization refers to the operational roomal units and their interconnections that realize the architectural specifications. Examples of organizational attributes include those ironw atomic number 18 details transpargonnt to the programmer, such as chink call attentions interfaces between the calculator and peripherals and the holding technology utilize.As an example, it is an architectural practice riposte whether a calculator will have a cover instruction. It is an organizational issue whether that instruction will implemented by a special spawn unit or by a mechanism that makes repeat use of the add unit of the system. The organizational decision may be establish on the anticipated frequency of use of the multiply instruction, the relative make haste of the two approaches, and the cost and physical size of a special multiply unit. Historically, and still today, the distinction between architecture and organization has been an important one. galore(postnominal) computing railway car manufacturers offer a family of calculating machine models, all with the same(p) architecture but with differences in organization.Consequently, the different models in the fami ly have different damage and performance characteristics. Further more than, a particular architecture may span many years and encompass a number of different ready reckoner models, its organization changing with changing technology. A great(p) example of twain these phenomena is the IBM governance/370 architecture. This architecture was setoff introduced in 1970 and included a number of models.The client with modest requirements could buy a cheaper, s pooh-pooh model and, if demand increase, by and by upgrade to a more expensive, faster model without having to abandon package that had already been developed. These parvenueer models retained the same architecture so that the customers softw ar investingwas protected. Remarkably, the System/370 architecture, with a less enhancements, has survived to this day as the architecture of IBMs mainframe product line.II. organize and FunctionA ready reckoner is a complex system contemporary computers contain millions of element ary electronic components. The key is to recognize the hierarchical nature of most complex systems, including the computer. A hierarchical system is a set of interrelated subsystems, each(prenominal) of the latter, in turn, hierarchical in organize until we reach around lowest direct of elementary subsystem. The hierarchical nature of complex systems is ingrained to both their design and their description. The designer need besides deal with a particular train of the system at a duration. At each level, the system consists of a set of components and their interrelationships.The behaviour at each level depends whole on a simplified, abstracted characterization of the system at the next dishonor level. At each level, the designer is concerned with mental synthesis and function Structure The way in which the components are interrelated Function The effect of each individual component as part of the expression The computer system will be described from the top down. We begi n with the major(ip)(ip) components of a computer, describing their structure and function, and proceed to successively cut layers of the hierarchy.FunctionBoth the structure and functioning of a computer are, in essence, simple. frame of reference 1.1 depicts the basic functions that a computer notify perform. In general terms, in that respect are plainly quaternary data butting The computer, of course, must be able to process information. The data may take a wide variety of forms, and the diverge of processing requirements is broad. However, we shall see that there are only a few total methods or types of data processing. data storage It is too essential that a computer retentiveness data. Even if the computer is processing on the fly (i.e., data come in and get processed, and the results go out immediately), the computer must temporarily store at least those pieces of data that are being worked on at any given moment. Thus, there is at least a short-term data stora ge function. as important, the computer performs a long-term data storagefunction. Files of data are stored on the computer for resultant retrieval and update.Data movement The computer must be able to move data between itself and the foreign world. The computers operating environment consists of tricks that serve as either sources or destinations of data. When data are received from or delivered to a plait that is directly connected to the computer, the process is known as input-output (I/O), and the device is referred to as a peripheral. When data are moved over longer distances, to or from a remote device, the process is known as data communications. fancy Finally there must be restrict of these three functions. Ultimately, this authorisation is exercised by the individual(s) who provides the computer with instructions. Within the computer, a supremacy unit manages the computers resources and orchestrates the performance of its functional parts in response to those ins tructions. insure 1.1 A FUNCTIONAL VIEW OF THE COMPUTERAt this general level of discussion, the number of possible operations that mass be performed is few. visit 1.2 depicts the four possible types of operations. The computer burn function as a data movement device (Figure 1.2a), simply transfer butt data from one peripheral or communications line to other. It can also function as a data storage device (Figure 1.2b), with data transferred from the external environment to computer storage (read) and vice versa (write). The final two diagrams show operations involving data processing, on data either in storage (Figure 1.2c) or en route between storage and the external environmentStructureFigure 1.3 is the simplest possible depiction of a computer. The computerinteracts in some expression with its external environment. In general, all of its linkages to the external environment can be classified as peripheral devices or communication lines. There are four main structural componen ts (Figure 1.4) Central Processing Unit ( processor) Controls the operation of the computer and performs its data processing functions often simple referred to as mainframeMain fund Stores dataI/O Moves data between the computer and its external environment System interconnection Some mechanism that provides for communication among CPU, main memory, and I/O go out 1.3 THE COMPUTERFIGURE 1.4 THE COMPUTER TOP-LEVEL STRUCTUREThere may be one or more of each of the aforementioned components. Traditionally, there has been just a one CPU. In recent years, there has been increasing use of multiple processors in a hit computer. The most interesting and in some ship canal the most complex component is the CPU its structure is depicted in Figure 1.5. Its major structural components are Control unit Controls the operation of the CPU and hence the computer Arithmetic and logic unit (ALU) Performs the computers data processing functions Registers Provides storage internal to the CPUCPU inter connection Some mechanism that provides for communication among the control unit, ALU, and registersFIGURE 1.5 THE profound PROCESSING UNIT (CPU)Finally, there are several approaches to the implementation of the control unit one common approach is a microprogrammed implementation. In essence, a microprogrammed control unit operates by executing microinstructions that define the functionality of the control unit. The structure of the control unit can be depicted as in Figure 1.6.FIGURE 1.6 THE CONTROL UNITIII.Importance of Computer Organization and ArchitectureThe computer lies at the heart of computing. Without it most of the computingdisciplines today would be a branch of the theoretical mathematics. To be a professional in any field of computing today, one should not regard the computer as just a black box that executes programs by magic. each students of computing should acquire some gaining and appreciation of a computer systems functional components, their characteristics, t heir performance, and their interactions. There are practical implications as well. Students need to understand computer architecture in order to structure a program so that it runs more efficiently on a real machine. In selecting a system to use, they should be able to understand the tradeoff among various components, such as CPU clock urge vs. memory size. Reported by the Joint Task Force on figure Curricula of the IEEE (Institute of Electrical and Electronics Engineers) Computer Society and ACM (Association for Computing Machinery).IV.Computer EvolutionA apprise history of computers is interesting and also serves the purpose of providing an overview of computer structure and function. A consideration of the need for balanced utilization of computer resources provides a stage setting that is useful.The First Generation Vacuum TubesENIAC The ENIAC (Electronic Numerical Integrator And Computer), designed by and fashioned under the supervision of fundament Mauchly and John Pres per Eckert at the University of Pennsylvania, was the worlds set-back general-purpose electronic digital computer. The project was a response to U.S. war duration needs during World War II. The Armys Ballistics seek Laboratory (BRL), an agency responsible for developing execute and trajectory tables for upstart weapons, was having difficulty supplying these tables accurately and within a reasonable time frame. Mauchly, a professor of electrical engineering at the University of Pennsylvania, and Eckert, one of his potash alum students, proposed to build a general-purpose computer using vanity undergrounds for the BRLs application. In 1943, the Army accepted this suggestion, and work began on the ENIAC.The resulting machine was enormous, deliberation 30 tons, occupying 1500 squre feet of floor space and containing more than 18,000 vacuum thermionic valves. When operating, it consumed 140 kilowatts of might. It was also substantially faster than any electromechanical compute r, being capable of 5000 additions per second. The ENIAC was a decimal ratherthan a binary machine. That is, numbers were represented in decimal form and arithmetic was performed in the decimal system. Its memory consisted of 20 accumulators, each capable of holding a 10-digit decimal number. A ring of 10 vacuum tubes represented each digit. At any time, only one vacuum tube was in the ON state, representing one of the 10 digits. The major drawback of the ENIAC was that it had to be programmed manually by setting switches and plugging and unplugging cables. The ENIAC was completed in 1946, too late to be used in the war effort. Instead, its first task was to perform a series of complex calculations that were used to dish out determine the feasibility of the hydrogen bomb.The use of the ENIAC for a purpose other than that for which it was built demonstrated its general-purpose nature. The ENIAC beard to operate under BRL attention until 1955, when it was disassembled. The von Neu mann Machine The task of entering and altering programs for the ENIAC was extremely tedious. The computer programming process could be facilitated if the program could be represented in a form suitable for storing in memory alongside the data. Then, a computer could get its instructions by reading them from memory, and a program could be set or altered by setting the values of a portion of memory. This idea, known as the stored-program theory, is usually attributed to the ENIAC designers, most notably the mathematician John von Neumann, who was a consultant on the ENIAC project.Alan Turing developed the idea at active the same time. The first publication of the idea was in a 1945 proposal by von Neumann for a new computer, the EDVAC (Electronic trenchant Variable automatic pistol Computer). In 1946, von Neumann and his colleagues began the design of a new stored-program computer, referred to as the IAS computer, at the Princeton Institute for Advanced Studies. The IAS computer , although not completed until 1952, is the prototype of all subsequent general-purpose computers. Figure 1.7 shows the general structure of the IAS computer. It consists of A main memory, which stores both data and instructionsAn arithmetic and logic unit (ALU) capable of operating on binary data A control unit, which interprets the instructions in memory and causes them to be executed Input and output (I/O) equipment operated by the control unitFIGURE 1.7 STRUCTURE OF THE IAS COMPUTERCommercial ComputersThe fifties axiom the birth of the computer fabrication with two companies, Sperry and IBM, dominating the market stick. UNIVAC I In 1947, Eckert and Mauchly formed the Eckert-Mauchly Computer Corporation to manufacture computers commercially. Their first successful machine was the UNIVAC I (Universal Automatic Computer), which was commissioned by the Bureau of the Census for the 1950 calculations. The Eckert-Mauchly Computer Corporation became part of the UNIVAC division of Spe rry-Rand Corporation, which went on to build a series of successor machines. The UNIVAC I was the first successful commercial computer. It was intended, as the throw implies, for both scientific and commercial applications. The first paper describing the system listed hyaloplasm algebraic computations, statistical problems, premium billings for a life insurance company, and logistical problems as a sample of the tasks it could perform.UNIVAC II The UNIVAC II which had greater memory capacity and high(prenominal) performance than the UNIVAC I, was delivered in the late fifties and illustrates several trends that have remained characteristic of the computer industry. First, advances in technology allow companies to advance to build larger, more powerful computers. Second, each company tries to make its new machines upward compatible with the older machines. This agency that the programs written for the older machines can be executed on the new machine. This strategy is adopted in the hopes of retaining the customer base that is, when a customer decides to buy a newer machine, he or she is likely to get it from the same company to avoid losing the investment in programs.The UNIVAC division also began development of the 1100 series of computers, which was to be its major source of revenue. This series illustrates a distinction that existed at one time. In 1955, IBM, which stands for International Business Machines, introduced the companion 702 product, which had a number of hardware features that suitable it to business applications. These were the first of a long series of 700/7000 computers that established IBM as the overwhelmingly dominant computer manufacturer.The Second Generation TransistorsThe first major change in the electronic computer came with the replacement of the vacuum tube by the transistor. The transistor is smaller, cheaper, and dissipates less(prenominal) heat than a vacuum tube but can be used in the same wayas a vacuum tube to constru ct computers. Unlike the vacuum tube, which requires wires, metal plates, a glass capsule, and a vacuum, the transistor is a substantialness device, made from silicon. The transistor was invented at Bell Labs in 1947 and by the 1950s had launched an electronic revolution. The National Cash Registers (NCR) and, more successfully, Radio Corporation of the States (RCA) were the front-runners with some small transistor machines.IBM followed shortly with the 7000 series. The second generation is worthy also for the appearance of the Digital Equipment Corporation (DEC). DEC was founded in 1957 and, in that year, delivered its first computer, the PDP-1 (Programmed Data Processor). This computer and this company began the minicomputer phenomenon that would become so prominent in the third generation. The IBM 7094 From the adit of the 700 series in 1952 to the introduction of the weather member of the 7000 series in 1964, this IBM product line underwent an evolution that is true of comp uter products. Successive members of the product line show increased performance, increased capacity, and/or lower cost.Table 1.1 illustrates this trend.The Third Generation Integrated lickA single, self-contained transistor is called a discrete component. Throughout the 1950s and early 1960s, electronic equipment was composed largely of discrete componentstransistors, resistors, capacitors, and so on. Discrete components were manufactured separately, packaged in their own containers, and soldered or wired unitedly onto masonite-like turn boards, which were wherefore installed in computers, oscilloscopes, and other electronic equipment. Early second-generation computer contained virtually 10,000 transistors. This figure grew to the hundreds of thousands, making the manufacture of newer, more powerful machines progressively difficult. In 1958 came the achievement that revolutionized electronics and started the era of microelectronics the invention of the interconnected circui t.Microelectronics Microelectronics means, literally, small electronics. Since the ancestrys of digital electronics and the computer industry, there has been a persistent and consistent trend toward the lessening in size of digital electronic circuits. The basic elements of a digital computer, as we know, must perform storage, movement, processing, and control functions. Only two fundamental types of components are required gates and memorycells.A gate is a device that implements a simple Boolean or logical function. a good deal(prenominal) devices are called gates because they control data flow in much the same way that canal gates do. The memory cell is a device that can store one touch of data that is, the device can be in one of two stable states at any time. By interconnecting large numbers of these fundamental devices, we can construct a computer. We can relate this to our four basic functions as followsData storage Provided by memory cells.Data processing Provided by gate s.Data movement The paths between components are used to move data from memory to memory and from memory through gates to memory.Control The paths between components can carry control signals. When the control signal is ON, the gate performs its function on the data inputs and produces a data output. Similarly, the memory cell will store the bit that is on its input lead when the WRITE control signal is ON and will place the bit that is in the cell on its output lead when the READ control signal is ON. Thus, a computer consists of gates, memory cells, and interconnections among these elements. The corporate circuit exploits the fact that such components as transistors, resistors, and conductors can be fabricated from a semiconductor such as silicon. It is just now an extension of the solid-state art to fabricate an entire circuit in a tiny piece of silicon rather than assemble discrete components made from separate pieces of silicon into the same circuit.Many transistors can be pr oduced at the same time on a single wafer of silicon. equally important, these transistors can be connected with a process of metallization to form circuits. Figure 1.8 depicts the key concepts in an integrated circuit. A thin wafer of silicon is dissever into a matrix of small areas, each a few millimetres square. The analogous circuit pattern is fabricated in each area, and the wafer is broken up into acts. Each chip consists of many gates and/or memory cells plus a number of input and output attachment points. This chip is then packaged in housing that protects it and provides pins for attachment to devices beyond the chip. A number of these packages can then be interconnected on a printed circuit board to produce larger and more complex circuits.As time went on, it became possible to pack more and more components on thesame chip. This harvesting in density is illustrated in Figure 1.9 it is one of the most rare technological trends ever recorded. This figure reflects the famous Moores law, which was propounded by Gordon Moore, cofounder of Intel, in 1965. Moore observed that the number of transistors that could be put on a single chip was doubling every year and correctly predicted that this pace would continue into the near future.FIGURE 1.9 GROWTH IN CPU TRANSISTOR accountThe consequences of Moores law are profound1.The cost of a chip has remained virtually unchanged during this period of rapid growth in density. This means that the cost of computer logic and memory circuitry has fallen at a dramatic rate. 2.Because logic and memory elements are placed closer together on more densely packed chips, the electrical path space is shortened, increasing operating renovate. 3.The computer becomes smaller, making it more convenient to place in a variety of environments. 4.There is a reduction in power and cooling requirements.5.The interconnections on the integrated circuit are much more reliable than solder connections. With more circuitry on each chi p, there are fewer interchip connections. IBM System/360 By 1964, IBM had a firm grip on the computer market with its 7000 series of machines. In that year, IBM announced the System/360, a new family of computer products. Although the announcement itself was no surprise, it contained some unpleasant news program for current IBM customers the 360 product line was incompatible with older IBM machines.Thus, the transition to the 360 would be difficult for the current customer base. This was a bold step by IBM, but one IBM felt was necessary to break out of some of the constraints of the 7000 architecture and to produce a system capable of evolving with the new integrated circuit technology. The 360 was the success of the decade and cemented IBM as the overwhelmingly dominant computer vendor, with a market share above 70%. The System/360 was the industrys first planned family of computers. The family covered a wide range of performance and cost. Table 1.2 indicates some of the key char acteristics of the various models in 1965.The concept of a family of compatible computers was both novel and extremely successful. The characteristics of a family are as follows Similar or identical instruction set The program that executes on one machine will also execute on any other. Similar or identical operating system The same basic operating system is available for all family members. Increasing speed the rate of instruction execution increases in going from lower to higher family members. Increasing number of I/O ports In going from lower to higher family members. Increasing memory size In going from lower to higher family members. Increasing cost In going from lower to higher family members.DEC PDP-8 Another momentous first shipment occurred PDP-8 from DEC. At a time when the average computer required an air-conditioned room, the PDP-8 (dubbed a minicomputer by the industry) was small enough that it could be placed on top of a lab bench or be built into other equipment. It could not do everything the mainframe could, but at $16,000, it was cheap enough for each lab technician to have one. The low cost and small size of the PDP-8 enabled another manufacturer to purchase a PDP-8 and integrate it into a total system for resale. These other manufacturers came to be known as original equipment manufacturers (OEMs), and the OEM market became and be a major segment of the computer marketplace. As DECs official history puts it, the PDP-8 established the concept of minicomputers, leading the way to a multibillion dollar industry.Later GenerationsBeyond the third generation there is less general agreement on defining generations of computers. Table 1.3 suggests that there have been a number of later generations, based on advances in integrated circuit technology. GenerationApproximate DatesTechnologyTypical Speed (operations persecond)With the rapid pace of technology, the high rate of introduction of new products and the importance of software and communicati ons as well as hardware, the classification by generation becomes less clear and less meaningful. In this section, we mention two of the most important of these results. Semiconductor Memory The first application of integrated circuit technology to computers was construction of the processor (the control unit and the arithmetic and logic unit) out of integrated circuit chips. precisely it was also found that this same technology could be used to construct memories. In the 1950s and 1960s, most computer memory was constructed from tiny go of ferromagnetic material, each about a sixteenth of an inch in diameter. These rings were strung up on grids of fine wires suspended on small screens inside the computer. Magnetized one way, a ring (called a core) represented a one magnetized the other way, it stood for a zero.It was expensive, bulky, and used destructive readout. Then, in 1970, Fairchild produced the first relatively capacious semiconductor memory. This chip, about the size of a single core, could hold 256 bits of memory. It was non-destructive and much faster than core. It took only 70 billionths of a second to read a bit. However, the cost per bit was higher than for that of core. In 1974, a seminal event occurred The price per bit of semiconductor memory dropped below the price per bit of core memory. pursuit this, there has been a continuing and rapid decline in memory cost accompanied by a corresponding increase in physical memory density. Since 1970, semiconductor memory has been through 11 generations 1K, 4K, 16K, 64K, 256K, 1M, 4M, 16M, 64M, 256M, and, as of this writing, 1G bits on a single chip.Each generation has provided four clock the storage density of the previous generation, accompanied by declining cost per bit and declining access time. Microprocessors Just as the density of elements on memory chips has go on to rise, so has the density of elements on processor chips. As time went on, more and more elements were placed on each chip, so that fewer and fewer chips were needed to construct a single computer processor. A discovery was achieved in 1971, when Intel developed its 4004. The 4004 was the first chip to contain all of the components of a CPU on a single chip the microprocessor was born. The 4004 can add two 4-bit numbers and can multiply only be repeated addition. By todays standards, the 4004 is hopelessly primitive, but it marked the beginning of a continuing evolution of microprocessor capability and power.

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