Question

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

I have been asked this question during an interview.

The above asked question is from Memory Protection Unit in section Memory Systems of Embedded Systems

Answer 1

Correct choice is (b) ARM protection memory management unit

For explanation I would say: 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.