NIMCET 2010 — Computer PYQ

Solution

The correct answer is: (c) Both (A) and (B)

Explanation

$I/O$ mapped $I/O$ (also known as Isolated $I/O$) is a method where the microprocessor treats memory and input/output devices as two separate entities.

• Distinct Address Spaces: In this scheme, the address space for memory and $I/O$ are separate. This means the CPU can have a memory address $0000H$ and an $I/O$ port address $0000H$ without conflict because it uses a control signal (like $IO/\overline{M}$) to distinguish between them.

• Limited Instructions: Unlike Memory Mapped $I/O$, where any instruction that references memory can be used for $I/O$, Isolated $I/O$ uses specific instructions (typically $IN$ and $OUT$) to perform data transfers. General data transfer instructions used for memory (like $MOV$ or $LDA$) cannot be used for $I/O$ devices.