This set of Embedded Systems Multiple Choice Questions & Answers (MCQs) focuses on “Memory Protection Unit”.
1. How many regions are created by the memory range in the ARM architecture?
a) 4
b) 8
c) 16
d) 32
View Answer
Explanation: The memory protection unit in the ARM architecture divides the memory into eight separate regions. Each region can be small as well as big ranging from 4 Kbytes to 4 Gbytes.
2. How many bits does the memory region in the ARM memory protection unit have?
a) 1
b) 2
c) 3
d) 4
View Answer
Explanation: The memory region possesses three bits which are the cacheable bit, bufferable bit and access permission bit.
3. Which of the following uses a priority level for permitting data?
a) ARM memory management unit
b) ARM protection memory management unit
c) Bus interface unit
d) Execution unit
View Answer
Explanation: In the ARM protection architecture, the memory is divided into some regions of size 4 Kbytes to 4 Gbytes. These regions possess bits called the cacheable bit, buffer bit, and access permitted bits. The regions are numbered as per priority level for which the permission bits takes the precedence if any of the regions gets overlapped.
4. What type of bit in the ARM memory mimics to that of the protection unit of ARM management unit?
a) permission bit
b) buffer bit
c) cacheable bit
d) access permission bit
View Answer
Explanation: The ARM architecture memory protection unit divides the memory range into different regions of size ranging from 4 Kbytes to 4 Gbytes. Each region is associated with certain bits called the cacheable bit, buffer bit, and access permitted bit. These bits are similar to the permission bit in the ARM memory management unit architecture which is stored in the control register.
5. Which of the following bits are used to control the cache behaviour?
a) cacheable bit
b) buffer bit
c) cacheable bit and buffer bit
d) cacheable bit, buffer bit and permission access bit
View Answer
Explanation: The cacheable bit and the buffer bit are used to control the behaviour of cache. Depending on the cacheable bit and the buffer bit, the memory access will complete successfully.
6. Which of the following unit provides security to the processor?
a) bus interface unit
b) execution unit
c) peripheral unit
d) memory protection unit
View Answer
Explanation: The memory management unit and the memory protection unit provides security to the processor by trapping the invalid memory accesses before they corrupt other data.
7. Which of the following includes a tripped down memory management unit?
a) memory protection unit
b) memory real mode
c) memory management unit
d) bus interface unit
View Answer
Explanation: The memory protection unit allows a tripped memory down memory management unit in which the memories are partitioned and protected without any address translation. This can remove the time consumption in the address translation thereby increases the speed.
8. Which of the following can reduce the chip size?
a) memory management unit
b) execution unit
c) memory protection unit
d) bus interface unit
View Answer
Explanation: The memory protection unit have many advantages over the other units. It can reduce the chip size, cost and power consumption.
9. How does the memory management unit provide the protection?
a) disables the address translation
b) enables the address translation
c) wait for the address translation
d) remains unchanged
View Answer
Explanation: The memory management unit can be used as a protection unit by disabling the address translation that is, the physical address and the logical address are the same.
10. Which of the following is used to start a supervisor level?
a) error signal
b) default signal
c) wait for the signal
d) interrupt signal
View Answer
Explanation: If memory access from the software does not access the correct data, an error signal is generated which will start a supervisor level software for the decision.
11. What happens when a task attempts to access memory outside its own address space?
a) paging fault
b) segmentation fault
c) wait
d) remains unchanged
View Answer
Explanation: Different tasks assign their own address space and whenever a task access memory outside its own address space, a segmentation fault result and which in turn results in the termination of the offending application.
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