FOXBORO FBM09输入控制模块
标准硬件电路仅为外围设备保留1024字节的I/O寻址空间，从I/O$000到$3FF。所有标准的PC I/O外围设备，如串行和并行端口、硬盘和软盘驱动器控制器、视频系统、实时时钟、系统计时器和中断控制器，都位于该I/O空间区域。BIOS正确初始化和配置所有这些寄存器；通常不需要直接调整这些I/O端口。I/O地址映射系统中断中总结了分配的和用户可用的I/O地址。除I/O端口地址外，I/O设备还具有单独的硬件中断线分配。分配给每个中断线的是内存中$00000至$003FF的256向量中断表中的相应中断向量。表2-3列出了16个可屏蔽中断和单个不可屏蔽中断（NMI）及其功能。第43页的表2-4详细说明了中断向量表中的向量。在第43页的表2-4中，还定义了十六进制和十进制中断数用于实模式和保护模式。
Standard hardware circuitry reserves only 1,024 byte of I/O addressing space from
I/O $000 to $3FF for peripherals. All standard PC I/O peripherals, such as serial and
parallel ports, hard and floppy drive controllers, video system, real-time clock, system
timers and interrupt controllers are addressed in this region of I/O space. The BIOS
initializes and configures all these registers properly; adjusting these I/O ports
directly is not normally necessary.
The assigned and user-available I/O addresses are summarized in the I/O Address
Map System Interrupts
In addition to an I/O port address, an I/O device has a separate hardware interrupt
line assignment. Assigned to each interrupt line is a corresponding interrupt vector in
the 256-vector interrupt table at $00000 to $003FF in memory. The 16 maskable
interrupts and the single Non-Maskable Interrupt (NMI) are listed in Table 2-3 along
with their functions. Table 2-4 on page 43 details the vectors in the interrupt vector
table. The interrupt number in HEX and decimal are also defined for real and
protected mode in Table 2-4 on page 43.
