【導(dǎo)讀】和結(jié)構(gòu)比例等組成要素；同時(shí)，以實(shí)例說(shuō)明如何選擇這些開(kāi)發(fā)要素。這不僅表現(xiàn)在從事嵌入式系統(tǒng)開(kāi)發(fā)研究的人員隊(duì)伍日益壯大，嵌入式處理器和。嵌入式系統(tǒng)領(lǐng)域趕超世界先進(jìn)水平。要達(dá)到這個(gè)目標(biāo)，具有一定的現(xiàn)實(shí)可行性，這是。因?yàn)橥琍C機(jī)系統(tǒng)相比，嵌入式系統(tǒng)更有自身的特征。式市場(chǎng)中不存在壟斷的局面。供應(yīng)用編程接口，向下屏蔽具體硬件特性的板級(jí)支持包BSP。軟件和硬件緊密配合，協(xié)調(diào)工作，共同完成系統(tǒng)預(yù)定的功能。Motorola和MIPS，其中ARM公司的芯片銷售量達(dá)，市場(chǎng)份額超過(guò)50%。大小和功耗指標(biāo)等。RTOS與一般商用多任務(wù)OS有共同的一面，一般RTOS內(nèi)核都很小，在幾KB~十幾KB之間。需求和流行RTOS的性能指標(biāo)及性價(jià)比選擇商用RTOS，如WinCE、VxWorks等；件研究中心研制的Hopen等。這些不同名稱的RTOS，核心軟件差異微妙而且難以。開(kāi)銷、RTOS內(nèi)存管理模式、最大中斷禁止時(shí)間和最大任務(wù)切換時(shí)間。RTOS的購(gòu)買(mǎi)成本和提供的技術(shù)支持等相關(guān)因素。針對(duì)實(shí)時(shí)性要求較高的應(yīng)用，需要

　　

【正文】 were so tired of。 and they were to see the ships of twenty navies the customs and costumes of twenty curious peoples the great cities of half a world they were to hobnob with nobility and hold friendly converse with kings and princes, grand moguls, and the anointed lords of mighty empires! It was a brave conception。 it was the offspring of a most ingenious brain. It was well advertised, but it hardly needed it: the bold originality, the extraordinary character, the seductive nature, and the vastness of the enterprise provoked ment everywhere and advertised it in every household in the land. Who could read the program of the excursion without longing to make one of the party? I will insert it here. It is almost as good as a map. As a text for this book, nothing could be better: EXCURSION TO THE HOLY LAND, EGYPT, THE CRIMEA, GREECE, AND INTERMEDIATE POINTS OF INTEREST. BROOKLYN, February 1st, 1867 The undersigned will make an excursion as above during the ing season, and begs to submit to you the following programme: A firstclass steamer, to be under his own mand, and capable of acmodating at least one hundred and fifty cabin passengers, will be selected, in which will be taken a select pany, numbering not more than threefourths of the ship39。s capacity. There is good reason to believe that this pany can be easily made up in this immediate vicinity, of mutual friends and acquaintances. The steamer will be provided with every necessary fort, including library and musical instruments. An experienced physician will be on board. Leaving New York about June 1st, a middle and pleasant route will be taken across the Atlantic, and passing through the group of Azores, St. Michael will be reached in about ten days. A day or two will be spent here, enjoying the fruit and wild scenery of these islands, and the voyage continued, and Gibraltar reached in three or four days. A day or two will be spent here in looking over the wonderful subterraneous fortifications, permission to visit these galleries being readily obtained. From Gibraltar, running along the coasts of Spain and France, Marseilles will be reached in three days. Here ample time will be given not only to look over the city, which was founded six hundred years before the Christian era, and its artificial port, the finest of the kind in the Mediterranean, but to visit Paris during the Great Exhibition。 and the beautiful city of Lyons, lying intermediate, from the heights of 21 which, on a clear day, Mont Blanc and the Alps can be distinctly seen. Passengers who may wish to extend the time at Paris can do so, and, passing down through Switzerland, rejoin the steamer at Genoa. From Marseilles to Genoa is a run of one night. The excursionists will have an opportunity to look over this, the magnificent city of palaces, and visit the birthplace of Columbus, twelve miles off, over a beautiful road built by Napoleon I. From this point, excursions may be made to Milan, Lakes Como and Maggiore, or to Milan, Verona (famous for its extraordinary fortifications), Padua, and Venice. Or, if passengers desire to visit Parma (famous for Correggio39。s frescoes) and Bologna, they can by rail go on to Florence, and r any who may prefer to go to Rome from that point), the distance will be made in about thirty six hours。 the route will lay along the coast of Italy, close by Caprera, Elba, and Corsica. Arrangements have been made to take on board at Leghorn a pilot for Caprera, and, if practicable, a call will be made there to visit the home of Garibaldi. long the east coast of Sicily, and in sight of Mount Etna, along the south coast of Italy, the west and south coast of Greece, in sight of ancient Crete, up Athens Gulf, and into the Piraeus, Athens will be reached in two and a half or three days. After tarrying here awhile, the Bay of Salamis will be crossed, and a day given to Corinth, whence the voyage will be continued to Constantinople, passing on the way through the Grecian Archipelago, the Dardanelles, the Sea of Marmora, and the mouth of the Golden Horn, and arriving in about forty eight hours from Athens. o, it39。s not, I said. It39。s my mother. Oh. Bysshe reached for the receiver. Why isn39。t she using her signature? Because she knows I don39。t want to talk to her. She must have found out what Perdita39。s done. Your daughter Perdita? he asked, holding the receiver against his chest. The one with the little girl? No, that39。s Viola. Perdita39。s my younger daughter. The one with no sense. What39。s she done? She39。s joined the Cyclists. Bysshe looked enquiringly blank, but I was not in the mood to enlighten him. Or in the mood to talk to Mother. I know exactly what Mother will say. She39。ll ask me why I didn39。t tell her, and then she39。ll demand to know what I39。m going to do about it, and there is nothing I can do about it, or I obviously would have done it alrea dy. Bysshe looked bewildered. Do you want me to tell her you39。re in court? No. I reached for the receiver. I39。ll have to talk to her sooner or later. I took it from him. Hello, Mother, I said. Traci, Mother said dramatically, Perdita has bee a Cyclist. I know. Why didn39。t you tell me? I thought Perdita should tell you herself. Perdita! She snorted. She wouldn39。t tell me. She knows what I39。d have to say about it. I