【正文】 t tell me. She knows 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。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。s done. Your daughter Perdita? he asked, holding the receiver against his chest. The one with the little girl? No, that39。s not, I said. It39。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。 they were to scamper about the decks by day, filling the ship with shouts and laughter or read novels and poetry in the shade of the smokestacks, or watch for the jelly fish and the nautilus over the side, and the shark, the whale, and other strange monsters of the deep。 How can I explain to you?39。 I assured her earnestly. 39。 and 39。 39。 I nodded. 39。 I agreed, but a little uncertain in my tone for not realizing what the secret was. 39。 39。Yes,39。t remember anyone saying before that I was a good boy. I knew no form of response designed to meet such an event. 39。t reach them. Then she nodded slowly, and said in words: 39。s mother was anxious and worried she did not give me the feeling that I was the one regrettable and unreliable factor in an otherwise orderly life, the way most people did at home. And the room itself seemed to me the better, too, for not having groups of words hanging on the wall for people to point to in disapproval. Inste ad, this room had several drawings of horses, which I thought very fine. Presently, Sophie, tidied up now, and with the tearmarks washed away, hopped to a chair at the table. Quite restored, but for the foot, she inquired with grave hospitality whether I liked eggs. Afterwards, Mrs Wender told me to wait where I was while she carried her upstairs. She returned in a few minutes, and sat down beside me. She took my hand in hers and looked at me seriously for some moments. I could feel her anxiety strongly 。s: she should grow no beard: she should have two breasts ...39。s back, and we all went back to the house together. The mandments and precepts one learns as a child can be remembered by rote, but they mean little until there is example — and, even then, the example needs to be recognized. Thus, I was able to sit patiently and watch the hurt foot being washed, coldpoulticed, and bound up, and perceive no connexion between it and the affirmation which I had heard almost every Sunday of my life. 39。 Her mother nodded slowly. She sighed. 39。 Sophie told her. 39。He39。Where is she?39。Oh!39。s mother?39。ll crawl,39。I39。 she said. 39。t,39。Go away! You mustn39。 Flash 模式減少了寶貴的 SRAM 資源需求、降低了產(chǎn)品開發(fā)成本，但是運行速度較 SRAM 模式慢。在內(nèi)存 SRAM 模式中，系統(tǒng)加 電冷啟動時，系統(tǒng)完成相關(guān)硬件初始化任務(wù)后執(zhí)行一段代碼，將系統(tǒng)編譯連接生成的二進(jìn)制可執(zhí)行代碼從 Flash存儲空間完全拷貝到 SRAM 內(nèi)存空間中，整個應(yīng)用程序調(diào)試完全在內(nèi)存空間執(zhí)行。選用 Multi_ICE 仿真器 ，支持在線仿真調(diào)試，通過并行口連接主機，支持程序編譯鏈接后的程序代碼快速加載，加快了代碼調(diào)試進(jìn)度。 XGW 開發(fā)平臺是自主研發(fā)的，軟件產(chǎn)品升級和故障排除比較容易，產(chǎn)品成本費用相對較低。 選定了 EP7211 后就應(yīng)選擇 RTOS 了。處理器外圍需要自帶語音錄放電路完成語音錄入和播放，串行口和紅外通信口進(jìn)行數(shù)據(jù)通信， LCD 接口電路提供用戶輸入接口，也需要電源管理模塊完成便攜式電子產(chǎn)品的低功耗設(shè)計。 5 應(yīng)用實例解析 在詳細(xì)討論了嵌入式系統(tǒng)開發(fā)中的幾個關(guān)鍵因素后，下面具體闡述這些因素在工作中的具體體現(xiàn)。 在項目開發(fā)中，分配開發(fā)人員時不僅要確保任務(wù)在給定時間期限內(nèi)完成的成功性，而且也要體現(xiàn)在鍛煉培養(yǎng)后繼人才方面。 公司運作以市場作為向?qū)?，是市場賦予它們生命。 4 開發(fā)隊伍的技術(shù)水平和結(jié)構(gòu)比例 嵌入式系統(tǒng)開發(fā)中選擇好了嵌入式處理器、 RTOS、仿真器和調(diào)試器等設(shè)備外，還需要考慮開發(fā)隊伍的技術(shù)水平和結(jié)構(gòu)比例。 應(yīng)用需求的多樣性導(dǎo)致市場上仿真器和調(diào)試器的提供商也較多， Windriver 公司的 Tornado 是一個很好的開發(fā)調(diào)試 工具?？焖僭头抡娣ㄓ糜谟布O(shè)備尚未完成時，直接在宿主機上對應(yīng)用程序運行進(jìn)行仿真分析。仿真器處理宿主機 和目標(biāo)機之間所有的通信，這個通信口可以是串口、并行口或者高速以太網(wǎng)接口。嵌入式系統(tǒng)開發(fā)調(diào)試和一般 PC 系統(tǒng)開發(fā)調(diào)試有較大差別。如果開發(fā)網(wǎng)絡(luò)應(yīng)用，還需要考慮該 RTOS 是否支持 TCP/IP 的網(wǎng)絡(luò)組件和 I/O服務(wù)等。針對實時性要求較高的應(yīng)用，需要重點考慮 RTOS 的最大中斷禁止時間和最大任務(wù)切換時間。 由于具體嵌入式應(yīng)用的功能需求差異以及不同 RTOS 間不同的性能指標(biāo)， RTOS的選擇有三種方案：一是根據(jù)應(yīng)用需要和公司技術(shù)實力，考慮自主開發(fā)研究（國內(nèi)手機廠商寧波波導(dǎo)公司部分款式的手機操作系統(tǒng)就是自主開發(fā)的）；二是充分考慮系統(tǒng)需求和流行 RTOS的性能指標(biāo)及性價比選擇商用 RTOS，如 WinCE、 VxWorks 等；三是考慮嵌入式 Linux（ RT_Linux）， RT_Linux是開放源代碼的免費自由軟件，互聯(lián)網(wǎng)技術(shù)論壇較多，具備較好的裁減性以支持不同的應(yīng)用范疇。 RTOS與一般商用多任務(wù) OS（如 Unix、 Windows 以及 Linux等）有共同的一面，也有不同的一面。如簡單的智能儀器 儀表 設(shè)計考慮使用 4位或者 8位低檔單片機 8051；和數(shù)字信號處理密切相關(guān)的選用 TI公司的 TMX320x系列的 DSP（數(shù)字信號處理）芯片；如果產(chǎn)品偏重于通信功能，考慮 Motorola公司的嵌入式處理器 68K系列；如果產(chǎn)品功能比較齊全，可選用嵌入式處理器領(lǐng)域的后起之秀 ARM公司的高性能嵌入式處理器 ARM 芯片系列等。 第二個前提條件是，分析研究市場上各大廠商提供的各款嵌入式處理器的性能指標(biāo)，如功耗、體積、成本、可靠性、速度、處理能力、電磁兼容性等。 一是深入研究具體的嵌入式系統(tǒng)應(yīng)用需求，充分的應(yīng)用需求分析后獲取應(yīng)用系統(tǒng)的性能指標(biāo)。這些產(chǎn)品的上市，不僅豐富了嵌入式處理器產(chǎn)品，而且也更加方便了工程技術(shù)人員進(jìn)行嵌入式系統(tǒng)的技術(shù)開發(fā)和擴大嵌入式產(chǎn)品的應(yīng)用領(lǐng)域。在嵌入式系統(tǒng)的硬件設(shè)備中，嵌入處理器是整個系統(tǒng)的核心部件，其性能的好壞直接決定整個系統(tǒng)的運行效果。嵌入式系統(tǒng)中，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。 嵌入式系統(tǒng)擁有巨大的市場空間，我國應(yīng) 該抓住機遇，與時俱進(jìn)，奮起直追，在嵌入式系統(tǒng)領(lǐng)域趕超世界先進(jìn)水平。需要指出的是，這些要素之間不是彼此獨立，而是緊密相關(guān)，可能還會在某些方面相互沖突。二是在 SRAM 內(nèi)存模式調(diào)試完應(yīng)用程序的基礎(chǔ)上，執(zhí)行閃存 Flash調(diào)試，系統(tǒng)啟動后將中斷服務(wù)程序 ISR和少量的內(nèi)核代碼拷貝到 SRAM 后在 SRAM 中執(zhí)行，其它應(yīng)用程序在 Flash中執(zhí)行。關(guān)于嵌入式處理器 EP7211 和自主研發(fā)的 XGW軟件開發(fā)平臺等，開發(fā)人員都有一定的技術(shù)積累和豐富的工作經(jīng)驗。 關(guān)于集成開發(fā)調(diào)試環(huán)境，我們購