UGC NET CSE | November 2017 | Part 3 | Question: 5

Question

Which of the following is correct statement?

• A. In memory – mapped I/O, the CPU can manipulate I/O data residing in interface registers that are not used to manipulate memory words.
• B. The isolated I/O method isolates memory and I/O addresses so that memory address range is not affected by interface address assignment.
• C. In asynchronous serial transfer of data the two units share a common clock.
• D. In synchronous serial transmission of data the two units have different clocks.

Comments

I don't know why I'm unable to see the question (or it may be not uploaded yet). [Copy it from below and make the question perfect]

Here is the question



Which of the following is correct statement?

(1) In memory-mapped I/O, the CPU can manipulate I/O data residing in interface registers that are not used to manipulate memory words.

(2) The isolated I/O method isolates memory and I/O addresses so that memory address range is not affected by interface address assignment.

(3) In asynchronous serial transfer of data the two units share a common clock.

(4) In synchronous serial transmission of data the two units have different clocks.

Answer 1

Isolated I/O - In memory mapped I/O scheme we can use only one address space, while in isolated I/O address space is allocated to both memory and I/O devices. In total memory address some addresses are assigned to memories and some to I/O devices. But we have to assign the address for I/O devices are different from the addresses which have been assigned to memories. In this scheme remember that I/O device is also treated as a memory location. And one address is assigned to each memory location (unique address) and one address is assigned to each I/O device.

Option (3) and (4) are clearly neglegable.

Answer: (2)

Comments

I think A is right answer.

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why A should be right

Answer 2

Option B is true..

.In Isolated I/o we use io ports address to address them whereas in mem mapped io we use the same address space of memory that's why address space is affected. Hence in io mapped address space is not affected