Memory Mapped IO和IO Mapped IO参考8085微处理器的区别

因此，微处理器本身不能做任何事情，它需要与内存、额外的外围设备或 IO 设备链接。这种链接称为接口。

8085 中 I/O 设备的接口可以通过两种方式完成：

1. 内存映射 I/O 接口：
在这种接口中，我们分配一个内存地址，该地址的使用方式与我们使用普通内存位置的方式相同。

2. I/O 映射 I/O 接口：
一种将 8 位地址值分配给可使用 IN 和 OUT 指令访问的输入/输出设备的接口称为 I/O 映射 I/O 接口。

内存映射 I/O 接口和 I/O 映射 I/O 接口之间的区别：

Features	Memory Mapped IO	IO Mapped IO
Addressing	IO devices are accessed like any other memory location.	They cannot be accessed like any other memory location.
Address Size	They are assigned with 16-bit address values.	They are assigned with 8-bit address values.
Instructions Used	The instruction used are LDA and STA, etc.	The instruction used are IN and OUT.
Cycles	Cycles involved during operation are Memory Read, Memory Write.	Cycles involved during operation are IO read and IO writes in the case of IO Mapped IO.
Registers Communicating	Any register can communicate with the IO device in case of Memory Mapped IO.	Only Accumulator can communicate with IO devices in case of IO Mapped IO.
Space Involved	216 IO ports are possible to be used for interfacing in case of Memory Mapped IO.	Only 256 I/O ports are available for interfacing in case of IO Mapped IO.
IO/M` signal	During writing or read cycles (IO/M` = 0 ) in case of Memory Mapped IO.	During writing or read cycles (IO/M` = 1) in case of IO Mapped IO.
Control Signal	No separate control signal required since we have unified memory space in the case of Memory Mapped IO.	Special control signals are used in the case of IO Mapped IO.
Arithmetic and Logical operations	Arithmetic and logical operations are performed directly on the data in the case of Memory Mapped IO.	Arithmetic and logical operations cannot be performed directly on the data in the case of IO Mapped IO.