Microprocessor Multiple Choice Questions on “Real Address Mode of 80386, Protected Mode of 80386”.
1. The instructions available in the 80386 that are not available in its real address mode is
a) addressing techniques
b) instructions for protected address mode
c) instructions for interrupt handling
d) all of the mentioned
Answer: b
Clarification: All the instructions of 80386 are available in this mode except for those designed to work with or for protected address mode.
2. The unit that is disabled in real address mode is
a) central processing unit
b) memory management unit
c) paging unit
d) bus control unit
Answer: c
Clarification: The paging unit is disabled in real address mode.
3. To form a physical memory address, appropriate segment register contents are
a) shifted by left by 4 positions
b) added to 16-bit offset address
c) operated using one of addressing modes
d) all of the mentioned
Answer: d
Clarification: To form a physical memory address, appropriate segment register contents are shifted by left by 4 positions and then added to 16-bit offset address formed using one of addressing modes, in same way as in the 80386 real address mode.
4. The segments in 80386 real mode are
a) overlapped
b) non-overlapped
c) either overlapped or non-overlapped
d) none of the mentioned
Answer: c
Clarification: The segments in 80386 real mode are may be overlapped or non-overlapped.
5. The operation that can be performed on segments in 80386 real mode is
a) read
b) write
c) execute
d) all of the mentioned
Answer: d
Clarification: The segments in 80386 real mode can be read, written or executed, i.e. no protection is available.
6. The selectors contain the segment’s
a) segment limit
b) base address
c) access rights byte
d) all of the mentioned
Answer: d
Clarification: In protected mode, the contents of segment registers are used as selectors to address descriptors which contain the segment limit, base address and access rights byte of the segment.
7. The linear address is calculated by
a) effective address + segment base address
b) effective address – segment base address
c) effective address + physical address
d) effective address – physical address
Answer: a
Clarification: The effective address(offset) is added with segment base address to calculate linear address.
8. If the paging unit is enabled, then it converts a linear address into
a) effective address
b) physical address
c) segment base address
d) none of the mentioned
Answer: b
Clarification: The paging unit when enabled, it converts a linear address into physical address.
9. If the paging unit is disabled, then the linear address is used as
a) effective address
b) physical address
c) segment base address
d) none of the mentioned
Answer: b
Clarification: The linear address is used as a physical address if the paging unit is disabled.
10. The paging unit is enabled only in
a) virtual mode
b) addressing mode
c) protected mode
d) none of the mentioned
Answer: c
Clarification: The paging unit is enabled only in protected mode.
11. For a single task in protected mode, the 80386 can address the virtual memory of
a) 32 GB
b) 64 MB
c) 32 TB
d) 64 TB
Answer: d
Clarification: In protected mode, the 80386 can address 4 GB of physical memory and 64 TB of virtual memory per task.