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How IO ports are different from memory locations?
Port mapped I/O uses a separate, dedicated address space and is accessed via a dedicated set of microprocessor instructions. The difference between the two schemes occurs within the microprocessor. I/O devices are mapped into the system memory map along with RAM and ROM.
What is the size of address for IO devices?
The I/O address space consists of 2^(16) (64K) individually addressable 8-bit ports; any two consecutive 8-bit ports can be treated as a 16-bit port; and four consecutive 8-bit ports can be treated as a 32-bit port.
What is an IO address?
An I/O address, also called a “port address,” references a separate memory space on PC peripheral boards, a little bit similar to memory-mapped peripherals that use blocks of memory. Peripherals often use both methods: an I/O address for passing control signals and memory for transferring data.
How is memory mapped in memory mapped I / O?
Memory-mapped I/O uses the same address space to address both memory and I/O devices. The memory and registers of the I/O devices are mapped to (associated with) address values. So when an address is accessed by the CPU, it may refer to a portion of physical RAM, or it can instead refer to memory of the I/O device.
What do you call address for memory and I / O?
The address for I/O here is called ports. Here we have different read-write instruction for both I/O and memory. In this case every bus in common due to which the same set of instructions work for memory and I/O.
How is the address space of an I / O device isolated?
I/O devices have a separate address space from general memory, either accomplished by an extra “I/O” pin on the CPU’s physical interface, or an entire bus dedicated to I/O. Because the address space for I/O is isolated from that for main memory, this is sometimes referred to as isolated I/O.
Why do memory and I / O have the same address space?
In this case every bus in common due to which the same set of instructions work for memory and I/O. Hence we manipulate I/O same as memory and both have same address space, due to which addressing capability of memory become less because some part is occupied by the I/O. In this I/O address are called ports.