What is the difference between isolated I/O and memory mapped I/O? What are theadvantages and disadvantages of each

Isolated I/O and Memory Mapped I/O are two methods used for communicating between the processor and the I/O devices in a computer system.

1. Isolated I/O: In this method, specific address spaces are assigned for I/O devices, separate from the memory. The CPU uses IN and OUT instructions to perform data transfer with the I/O devices.

Advantages:

• It prevents the I/O devices from interfering with the memory because they have separate address spaces.
• It is simple to implement.

Disadvantages:

• The address space for I/O devices is limited, which can be a problem when there are many I/O devices.
• The data transfer rate is slower compared to Memory Mapped I/O.

2. Memory Mapped I/O: In this method, the I/O devices and the memory share the same address space. The CPU uses the same instructions (LOAD and STORE) for both memory and I/O device data transfers.

Advantages:

• It allows for more I/O devices as they share the address space with the memory.
• The data transfer rate is faster compared to Isolated I/O.

Disadvantages:

• There can be conflicts between the I/O devices and the memory as they share the same address space.
• It is more complex to implement compared to Isolated I/O.