端口映射的I/O地址空间的位置 [英] Location of Port mapped I/O address space

问题描述

我知道访问I/O地址空间中的端口需要特定的IN/OUT指令，并且它们不是物理内存(RAM)的一部分，但我不了解I/O地址空间实际位于何处(物理上)?(某种I/O控制器中的RAM)?物理内存的预留端?

I know access to ports in I/O address spaces requires specific IN/OUT instructions and they are not part of Physical memory( RAM) but I have not understood Where is the I/O address space actually located (Physically)? (some sort of RAM in )I/O controller? Reserved side of physical memory?

推荐答案

在早期的X86处理器(以及8080，Z80等)上，I/O地址空间与内存在同一数据和地址总线上，但是通过激活CPU上的专用IO请求引脚可以访问

On the early X86 processors (and also the 8080, Z80 etc) I/O address space was on the same data and address bus as the memory, but was accessed by activating a dedicated IO-request pin on the CPU

因此，电气I/O与RAM并行

So electrically I/O was in parallell with the RAM

这些天，CPU直接使用HDMI和PCIe，因此大部分I/O空间在CPU内部(例如VGA I/O接口)或通过PCIe串行总线进行访问PCIe还用于内存映射的I/O，因此在这方面，仍然可以通过与内存映射的IO几乎相同的电接口访问IO.但不再使用与RAM相同的IO引脚，

Thses days the CPU speaks HDMI and PCIe directly so much of the I/O space is either internal to the CPU (eg: the VGA I/O interface) or accessed over th serial bus that is PCIe PCIe is also used for memory mapped I/O so in that respect IO is still accessed over mostly the same electrical interfaces as memory mapped IO . but not over the same IO pins that are used for RAM any more,

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