the changing face of computing and the task of the computer designer

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the changing face of computing and the task of the computer designer article info abstract article history: received accepted available online keywords: computer designer, eembc, computing, pda, pc, digital signal, architecture, hardware, saftware in the 1960s, the dominant form of computing was on large mainframes, machines costing millions of dollars and stored in computer rooms with multiple operators overseeing their support. typical applications included business data processing and large­ scale scientific computing. the 1970s saw the birth of the minicomputer, a smaller sized machine initially focused on applications in scientific laboratories, but rapidly branching out as the technology of timesharing, multiple users sharing a computer interactively through independent terminals, became widespread. the 1980s saw the rise of the desktop computer based on microprocessors, in the form of both personal computers and workstations. he individually owned desktop computer replaced timesharing and led to the rise of servers, computers that provided larger­scale …
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dollar terms, is desktop computing. desktop computing spans from low­end systems that sell for under $1,000 to highend, heavily­configured workstations that may sell for over $10,000. throughout this range in price and capability, the desktop market tends to be driven to optimize price­ performance. this combination of performance (measured primarily in terms of compute performance and graphics performance) and price of a system is what matters most to customers in this market and hence to computer designers. as a result desktop systems often are where the newest, highest performance microprocessors appear, as well as where recently cost­reduced microprocessors and systems appear first (see section 1.4 on page 14 for a discussion of the issues affecting cost of computers). desktop computing also tends to be reasonably well characterized in terms of applications and benchmarking, though the increasing use of web­centric, interactive applications poses new challenges in performance evaluation.the pc portion of …
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fail; the challenge in a server is to maintain system availability in the face of component failures, usually through the use of redundancy. why is availability crucial? consider the servers running yahoo!, taking orders for cisco, or running auctions on ebay. obviously such systems must be operating seven days a week, 24 hours a day. failure of such a server system is far more catastrophic than failure of a single desktop. although it is hard to estimate the cost of downtime, figure 1 shows one analysis, assuming that downtime is distributed uniformly and does not occur solely during idle times. as we can see, the estimated costs of an unavailable system are high, and the estimated costs in figure 1 are purely lost revenue and do not account for the cost of unhappy customers! figure 1 the cost of an unavailable system is shown by analyzing the cost of downtime …
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bvious, are the fastest growing portion of the computer market. the range of application of these devices goes from simple embedded microprocessors that might appear in a everyday machines (most microwaves and washing machines, most printers, most networking switches, and all cars contain such microprocessors) to handheld digital devices (such as palmtops, cell phones, and smart cards) to video games and digital set­top boxes. although in some applications (such as palmtops) the computers are programmable, in many embedded applications the only programming occurs in connection with the initial loading of the application code or a later software upgrade of that application. thus, the application can usually be carefully tuned for the processor and system; this process sometimes includes limited use of assembly language in key loops, although time­to­market pressures and good software engineering practice usually restrict such assembly language coding to a small fraction of the application. this use of …
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eeting the performance need at a minimum price, rather than achieving higher performance at a higher price. often, the performance requirement in an embedded application is a real­time requirement. a real­time performance requirement is one where a segment of the application has an absolute maximum execution time that is allowed. for example, in a digital set­top box the time to process each video frame is limited, since the processor must accept and process the next frame shortly. in some applications, a more sophisticated requirement exists: the average time for a particular task is constrained as well as the number of instances when some maximum time is exceeded. such approaches (sometimes called soft real­time) arise when it is possible to occasionally miss the time constraint on an event, as long as not too many are missed. real­time performance tend to be highly application dependent. it is usually measured using kernels either …

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the changing face of computing and the task of the computer designer article info abstract article history: received accepted available online keywords: computer designer, eembc, computing, pda, pc, digital signal, architecture, hardware, saftware in the 1960s, the dominant form of computing was on large mainframes, machines costing millions of dollars and stored in computer rooms with multiple operators overseeing their support. typical applications included business data processing and large­ scale scientific computing. the 1970s saw the birth of the minicomputer, a smaller sized machine initially focused on applications in scientific laboratories, but rapidly branching out as the technology of timesharing, multiple users sharing a computer interactively through independent terminals, be...

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