ISRO | ISRO CS 2018 | Question 16

Of the following, which best characterizes computers that use memory-mapped I/O?

(A) The computer provides special instructions for manipulating I/O ports
(B) I/O ports are placed at addresses on the bus and are accessed just like other memory locations
(C) To perform I/O operations, it is sufficient to place the data in an address register and call channel to perform the operation
(D) I/O can be performed only when memory management hardware is turned on


Answer: (B)

Explanation: 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.

Option (B) is correct.

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