Introduction to Computer Organization and Computer Evolution Essay

In describing computing machines, a distinction is often made amidst information touch on agreement architecture and electronic ready reckoner organization. Although it is difficult to give precise definitions for these terms, a consensus exists about the general argonas covered by each. calculator Architecture refers to those attributes of a governing body tangible to a political platformmer or, put another mien, those attributes that control a direct impact on the logical execution of a architectural plan. Examples of architectural attributes include the study set, the minute of bits used to represent various information types (e.g., proceedss, characters), I/O mechanisms, and techniques for addressing retentiveness. Computer Organization refers to the operational social units and their interconnections that realize the architectural specifications. Examples of organizational attributes include those computing machine hardware details transparent to the prog rammer, much(prenominal) as control requests interfaces between the data processor and peripherals and the recollection technology used.As an example, it is an architectural design issue whether a information processing system invariablyyow for have a multiply instruction. It is an organizational issue whether that instruction will implemented by a special multiply unit or by a mechanism that makes repeated use of the add unit of the system. The organizational decision may be based on the anticipated frequency of use of the multiply instruction, the relative speed of the two arisees, and the hail and physical coat of a special multiply unit. Historic in ally, and still forthwith, the distinction between architecture and organization has been an all important(predicate) one. M each computing device manufacturers offer a family of computer models, all with the same architecture but with differences in organization.Consequently, the different models in the family have dif ferent price and performance characteristics. Furthermore, a particular architecture may span many years and encompass a weigh of different computer models, its organization changing with changing technology. A prominent example of both these phenomena is the IBM System/370 architecture. This architecture was startle introduced in 1970 and included a number of models.The client with modest requirements could buy a cheaper, slower model and, if demand increased, later upgrade to a more expensive, faster model without having to abandon software system that had already been highly-developed. These newer models retained the same architecture so that the customers software investmentwas protected. Remarkably, the System/370 architecture, with a few enhancements, has survived to this day as the architecture of IBMs mainframe product line.II. social system and FunctionA computer is a complex system contemporary computers contain millions of elementary electronic components. The key is to recognize the ranked nature of nigh complex systems, including the computer. A hierarchical system is a set of interrelated subsystems, each of the latter, in turn, hierarchical in structure until we chain some lowest level of elementary subsystem. The hierarchical nature of complex systems is essential to both their design and their description. The designer need only when deal with a particular level of the system at a time. At each level, the system consists of a set of components and their interrelationships.The behaviour at each level depends only on a simplified, abstracted characterization of the system at the next lower level. At each level, the designer is concerned with structure and usage Structure The way in which the components are interrelated Function The operation of each individual component as part of the structure The computer system will be described from the top down. We begin with the major components of a computer, describing their structure and functi on, and proceed to successively lower layers of the hierarchy.FunctionBoth the structure and functioning of a computer are, in essence, simple. visualise 1.1 depicts the canonic functions that a computer loafer perform. In general terms, there are only quadruple Data processing The computer, of course, moldiness be able to process data. The data may take a wide variety of forms, and the range of processing requirements is broad. However, we shall see that there are only a few fundamental methods or types of data processing. Data shop It is also essential that a computer store 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 to the lowest degree those pieces of data that are being worked on at any given moment. Thus, there is at least a short-term data storage function. evenly important, the computer performs a long-term data storagefunction. Files of data are stored on the computer for subsequent retrieval and update.Data shanghaiment The computer must be able to move data between itself and the outside field. The computers in operation(p) environment consists of whirls that serve as either sources or destinations of data. When data are received from or delivered to a device 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. Control Finally there must be control of these three functions. Ultimately, this control is exercised by the individual(s) who provides the computer with instructions. Within the computer, a control unit manages the computers resources and orchestrates the performance of its functional parts in response to those instructions.FIGURE 1.1 A FUNCTIONAL VIEW OF THE data processorAt this general level of discussion, the n umber of attainable operations that can be performed is few. Figure 1.2 depicts the four possible types of operations. The computer can function as a data movement device (Figure 1.2a), simply transferring data from one peripheral or communications line to another. 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 fashion 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 components (Figure 1.4) key Processing Unit ( central processor) Controls the operation of the computer and p erforms its data processing functions often simple referred to as processorMain shop 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/OFIGURE 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 hit CPU. In recent years, there has been increasing use of multiple processors in a single computer. The most interesting and in some ways the most complex component is the CPU its structure is pictured in Figure 1.5. Its major structural components are Control unit Controls the operation of the CPU and thusly the computer Arithmetic and logic unit (ALU) Performs the computers data processing functions Registers Provides storage internal to the CPUCPU interconnection Some mechanism that provides for communication among the control unit, ALU, and registersFI GURE 1.5 THE CENTRAL 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 like a shot 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. All students of computing should acquire some understanding and appreciation of a computer systems functional components, their characteristics, their performance, and their interactions. There are practical implications as well. Students n eed 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 speed vs. memory size. Reported by the Joint Task Force on work out Curricula of the IEEE (Institute of Electrical and Electronics Engineers) Computer Society and ACM (Association for Computing Machinery).IV.Computer EvolutionA brief 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 context that is useful.The First Generation Vacuum TubesENIAC The ENIAC (Electronic Numerical Integrator And Computer), designed by and constructed under the supervision of John Mauchly and John Presper Eckert at the University of Pennsylvania, was the worlds firstly general-purpose electronic digital co mputer. The project was a response to U.S. wartime needs during World War II. The ground forcess Ballistics question Laboratory (BRL), an agency responsible for developing range and trajectory tables for new 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 graduate students, proposed to build a general-purpose computer using vacuum tubes for the BRLs application. In 1943, the Army accepted this proposal, and work began on the ENIAC.The resulting machine was enormous, weighing 30 tons, occupying 1500 squre feet of floor space and containing more than 18,000 vacuum tubes. When operating, it consumed 140 kilowatts of big businessman. It was also substantially faster than any electromechanical computer, being capable of 5000 additions per second. The ENIAC was a decimal ratherthan a binary machine. That is, numbers were represent ed 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 accurate in 1946, too late to be used in the war effort. Instead, its first task was to perform a serial of complex calculations that were used to inspection and repair determine the feasibility of the hydrogen bomb.The use of the ENIAC for a purpose other than that for which it was construct demonstrated its general-purpose nature. The ENIAC continued to operate under BRL management until 1955, when it was disassembled. The von von Neumann Machine The task of entering and altering programs for the ENIAC was extremely tedious. The programm ing process could be facilitated if the program could be represented in a form adapted 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 concept, 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 about the same time. The first publication of the idea was in a 1945 proposal by von Neumann for a new computer, the EDVAC (Electronic decided Variable Automatic 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 1950s saw the birth of the computer industry with two companies, Sperry and IBM, dominating the marketplace. 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 grade of Sperry-Rand Corporation, which went on to build a series of successor machines. The UNIVAC I was the first successful commercial computer. It w as intended, as the name implies, for both scientific and commercial applications. The first paper describing the system listed matrix 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 higher performance than the UNIVAC I, was delivered in the late 1950s and illustrates several trends that have remained characteristic of the computer industry. First, advances in technology forfeit companies to continue to build larger, more powerful computers. Second, each company tries to make its new machines upward compatible with the older machines. This means 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 suited 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 venialer, cheaper, and dissipates less heat than a vacuum tube but can be used in the same wayas a vacuum tube to construct computers. Unlike the vacuum tube, which requires wires, metal plates, a glass capsule, and a vacuum, the transistor is a substantialness device, made from ti. The tran sistor 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 genesis is noteworthy 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 introduction of the 700 series in 1952 to the introduction of the last member of the 7000 series in 1964, this IBM product line underwent an evolution that is typical of computer products. Successive members of the product line show increased performance, increased capacity, and/or lower cost. skirt 1.1 illustrates this trend.The Third Generat ion Integrated CircuitA 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 together onto masonite-like circuit boards, which were then installed in computers, oscilloscopes, and other electronic equipment. Early second-generation computer contained about 10,000 transistors. This figure grew to the hundreds of thousands, making the manufacture of newer, more powerful machines increasingly difficult. In 1958 came the achievement that revolutionized electronics and started the era of microelectronics the invention of the merged circuit.Microelectronics Microelectronics means, literally, small electronics. Since the beginnings of digital electronics and the computer industry, there has been a persistent and consistent t rend toward the reduction 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 call for gates and memorycells.A gate is a device that implements a simple Boolean or logical function. Such 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 bit 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 gates.Data movement The classs 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 integrated circuit exploits the fact that such components as transistors, resistors, and conductors can be fabricated from a semiconductor such as silicon. It is merely an extension of the solid-state art to fabricate an entire circuit in a critical piece of silicon rather than assemble discrete components made from separate pieces of silicon into the same circuit.Many transistors can be produced 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 integra ted circuit. A thin wafer of silicon is divided into a matrix of small areas, each a few millimetres square. The identical circuit pattern is fabricated in each area, and the wafer is broken up into chips. 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 growth in density is illustrated in Figure 1.9 it is one of the most remarkable 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(prenominal) year and corr ectly predicted that this pace would continue into the near future.FIGURE 1.9 GROWTH IN CPU TRANSISTOR COUNTThe consequences of Moores law are healthy1.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 go at a dramatic rate. 2.Because logic and memory elements are placed closer together on more densely packed chips, the electrical path length is shortened, increasing operating speed. 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 chip, there are less 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 comput er products. Although the announcement itself was no surprise, it contained some unpleasant news 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 characteristics 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 integr ate 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 rest 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 sawhorse 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 communications 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. But 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 rings 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 to a lower place the price per bit of core memory. Following 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 times 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 hascontinued 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 less and fewer chips were needed to construct a single computer processor. A breakthrough was achieved in 1971, when Intel developed its 4004. The 4004 was the first chip to contain all of the com ponents 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.