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Unformatted text preview: chapter 1 cunnutor Abstractions unu homology microprocessors found in your car, the computers in a cell phone. the computers in a video game or television, and the networks of proccssors that control a mud cm airplane or cargo ship. Embedded compuling systems are designed to run one application or one set of related applications. that are normally integrated with the hardware and delivered as it single system; thus. despite the large number of embedded computers, most users never really see that they are using a computer! Figure 1.1 shows lllat during the last several years. the growth in cellphones that rely on embedded computers has been much faster than the growth rate ofdcslstop computers. Note that the embedded computers are also Found in digital TVs and set-top boxes. automobiles. digital cameras, music players, video games, and a variety of other such consumer devices. which further increases the gap between the number of embedded computers and desktop computers. I Cell Phones l PCs El TVs 1200 r 1100 1000 900 BBC! 700 600 500 400 SUD 200 . 100 0 Vs ’\ ’\ N ’7’ ‘5 seedeedeefio FIGURE 1.1 The number of can phones. pumnul computers. and televisions manufactured per year between 1551 and 2001'. (We have television data only lroni 1004.) Mot: than a billion new rrli phones were shipped or zoos Cell pin to lcs cxcccdcd pm by only a factor or' i i tow. hat the ratio grow to it 5 in mm. The Ioi-ai number in use in 2004 is estimated to be about 1,0“ It-I sinus. 1.315 cell phones. and a BB res. A: llii. i-Inrltl popularron was about a, ID in 3004. ihr-rc WU ppmhimnicly one PC, ‘llphbmss and 2.5 in orrsrorcvcryciphrpcoolc on ihrpinnr-i Ii zunssurvcyotus.fontilrcs round that thcy turned on .rvcropc i2 gadguls. including three TVs, 1 rat. and rrrircr dcrrccs such as gdme consolcr. Mild players. and cell phones 1.: lnhnduciinn Embedded applications otten have unique application requirements that combine a minimum performance with stringent limitations on cost or power. For example. consider rr music playc - the processor need only be as fast as necessary to handle its limited function. and beyond that. minimizing cost and power are the most important objectives. Despite their low cost. cmbcddcd computcts often have lower tolerance {or failure. since the results can vary from upsetting (when your new televi no crashes) to (Java. citing (such as might occur when the computer in a plane or cargo ship crashes). 1n consunrcr-orrcntcd cmbcddcd applications,s|lcli as s digital home appliance, dependability is achieved primarily through simplic- ity—theemphasis is on doing one function as perfectly aspos ble. ln lurgeeiubedc dcd systems, techniques of redundancy from the server world are often employed (see Section 6.9).Altlioiigh this book Focuses on generalrpurprrse computers. most concepts apply directly, or with slight modifications, in embedded computers. Elaboration: Elaoomtions are shun sections used throughoutthc textto provide more detail on a particular Subject that may be Of interest. Dislntereslen readers may skip over all eiaboration. since the subsequent material will never depend on the Contents cf the elaboration. Many embedded processors are designed using placessul cores. 3 Version Dfa Braces» surwritteri in a hardware description language. Such as Verilug Dr VHDL (see Chapter 4). The core allows a designer to Integrate other application-specific hardware with the pros cessor core for fabrication on a single Chip. What You Can Learn in This Book Successful programmers hayc always been concerned about the performance or their programs. because getting results to the user quickly is on cu] in creating successful sorhuare. in the 19605 and 19705. a primary constraint on computer performance was the size of the computer‘s memory. Thus. programmers often followed a simple credo: minimize memory space to male programs fast. In the last decode. advances in computer design and rncmory technology have greatly rccluccd thc importance of small memory size in most applications other than those in embedded computing systems. Programmers interested in performance now need to undciststnd the issues that have replaced the simple memory model of the 1960. the parallel nature of processors and the hierarchical nature afmemories. Programmers who seek lu build competitiveversionsoicornpilcrsoprroringsystems.dotabrorsnnderenapplications will therefore ncod to increase their knowledge of computer orgnni lion. We are honoi cd to have the opportunity to explain what’s inside this revolutionc any machine, unraveling the software below your program and the hardware under the covers of your computer. By the time you complete this book. we believe you will be able to answer the following questions: ...
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