各位好，小弟目前在看David E.Simon的 An Embedded Software Primer一書，遇到幾個看 不懂的地方想要請教 圖片1:http://imgur.com/a/6raMt 圖片2:http://imgur.com/a/6XaKz 圖片3:http://imgur.com/a/BLsyf 圖片4:http://imgur.com/a/3jr39 Q1:請問在第1張圖片中，"A READ/ line, which it pulses or strobes low when it want to get data, and a WRITE/ line, which it pulses low when it want to write data out"，strobe low是什麼意思? Q2:一樣在第1張，"A clock signal input, which paces all of the work...."，pace all of the work是什麼意思? Q3: 在第2張中，我知道memory address space是什麼，就是可以拉到其他的chip然後提供 其他chip address，那它跟I/O address space差在哪裡呢? 換句話說，我也可以把連到 I/O address space的chip改成連到memory address space。從這本書的內文我看不出來這 兩個之間的差異。 Q4: 在第2張下面跟第3張第一句，"電路圖右上角的gate that drives the memory enable signal(MEMEN/) asserts that signal low when the I/O signal and A19 are both low. This enables the memory chips in the memory address space in the range from 0x00000 to 0x7ffff"，我不懂為什麼I/O signal跟A19為LOW時(此時MEMEN/輸出low) 會讓memory address sapce的range為0x00000~0x7ffff Q5: 在第4張圖中，"Note that since this circuit asserts DV1's chip enable signal whenever A19 and I/O are high and does not check A18 through A8, the circuit can read from or write to DV1 no matter what the values of those address signals"，請問，CPU只有A0~A15，為什麼會有到A18?還是這張圖畫錯了，是A0~A18? --

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