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发表于 2019-3-11 22:23:18
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①The I/O read and write operations are similar to the memory read and write operations.
I/O的读和写操作和类似于存储器的读写操作。
②A processor may use either memory mapped I/O or isolated I/O.
一个处理器可能使用I/O储存器或者独立的I/O端口中的一个。
③If the precessor supports memory mapped I/O,it follows the same sequences of opreations to input or output data as to
read data from or write data to memory,the sequences shown in Figure 2-2.
如果处理器提供I/O储存器,它跟随相同的根据在存储器中阅读资料和写资料去输入和输出的操作序列,这个序列展示在图2-2中。
④(Remember, in memory mapped I/O, the precessor treats an I/O port as a memory location, so it is reasonable to treat an
I/O data access the same as a memory access.)
记住,在I/O储存器中,处理器处理一个I/O端口就好像处理一个储存单元一样,所以它理所当然的像处理一个内存访问一样去处理一个I/O资料
访问。
⑤Precessors that ues isolated I/O follow the same precess but have a second control signal to distinguish between I/O and
memory accesses.
处理器使用独立的I/O端口,跟随一个相同的进程但是它有第二个控制信号,去区分I/O和储存器访问。
⑥(CPUs that use isolated I/O can have a memory location and an I/O port with the same address,which makes this extra signal necessary.)
处理器们使用独立的I/O端口,可以在一个相同的地址上拥有一个存储单元和一个I/O端口,这就是为什么这个额外的信号是必须的。 |
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