键盘中断如何始终在端口 60 上访问？

发布于 2025-01-11 00:39:57 字数 805 浏览 6 评论 0原文

我正在学习操作系统和引导加载程序。我发现，要读取键盘按键，可以使用端口 60 的 in 汇编助记符。即使在编写在现代计算机上运行的低级汇编程序时，这也有效。

我正在阅读此

keyhandler:
   in al, 0x60   ; get key data
   mov bl, al   ; save it
   mov byte [port60], al
 
   in al, 0x61   ; keybrd control
   mov ah, al
   or al, 0x80   ; disable bit 7
   out 0x61, al   ; send it back
   xchg ah, al   ; get original
   out 0x61, al   ; send that back
 
   mov al, 0x20   ; End of Interrupt
   out 0x20, al   ;
 
   and bl, 0x80   ; key released
   jnz done   ; don't repeat
 
   mov ax, [port60]
   mov  word [reg16], ax
   call printreg16

机器如何知道将插入例如任意 USB 连接器的键盘路由到端口 60，以便程序员可以访问它？

原文

I am in the process of learning about operating systems and bootloaders. I have found that, to read keyboard keypresses, one can use the in assembly mnemonic with port 60. This works even when writing low-level assembly programs running on a modern machine.

I was reading this article on the topic, in order to better understand this snippet:

keyhandler:
   in al, 0x60   ; get key data
   mov bl, al   ; save it
   mov byte [port60], al
 
   in al, 0x61   ; keybrd control
   mov ah, al
   or al, 0x80   ; disable bit 7
   out 0x61, al   ; send it back
   xchg ah, al   ; get original
   out 0x61, al   ; send that back
 
   mov al, 0x20   ; End of Interrupt
   out 0x20, al   ;
 
   and bl, 0x80   ; key released
   jnz done   ; don't repeat
 
   mov ax, [port60]
   mov  word [reg16], ax
   call printreg16

How does the machine know to route a keyboard plugged into, for example, an arbitrary USB connector to port 60 so it is accessible for the programmer?

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