Term of the Moment
active 3D
Definition: port-mapped I/O
The method used to pass signals from the CPU to the controller boards of peripheral devices on older Windows computers. An I/O address, also called a "port address," was a separate memory space on peripheral boards. Older Macs used memory-mapped I/O (MMIO). See PC I/O addressing.
Tiny Scattered Memory Banks
There was typically a 64K address space for I/O, although much less was generally used. Each port-mapped peripheral board contained a few bytes of memory set to a default address range, and one or more alternate addresses were provided to resolve conflicts. As long as each one was set to a different address, the CPU could transmit signals to the appropriate board.
I/O Address Operation
When a program needed to read and write data, it issued IN and OUT instructions with the port address rather than use the LOAD and STORE instructions that manipulate main memory. See Plug and Play.
I/O Addresses
Tiny Scattered Memory Banks
There was typically a 64K address space for I/O, although much less was generally used. Each port-mapped peripheral board contained a few bytes of memory set to a default address range, and one or more alternate addresses were provided to resolve conflicts. As long as each one was set to a different address, the CPU could transmit signals to the appropriate board.
I/O Address Operation
When a program needed to read and write data, it issued IN and OUT instructions with the port address rather than use the LOAD and STORE instructions that manipulate main memory. See Plug and Play.
Windows displays the details of I/O addresses and other internal settings. These I/O Properties were from Windows 98. See Win Technical details.