Question $2-($based on: $12\mathrm{.}8,12\mathrm{.}10$ p$.567$ and $14\mathrm{.}12,14\mathrm{.}13,$ p$.640)$

$20$

$(12\mathrm{.}8,$ p$\mathrm{.}567)$:

a$)$ what is the advantage of supporting memory$-$mapped $\frac{\text{I}}{o}$ to device$-$control registers?

b$)$ what is the disadvantage of supporting memory$-$mapped I$/$O to device$-$control registers? $(5)$

$(14\mathrm{.}12,$ p$\mathrm{.}640)$: Consider a file system that uses inodes to represent files. Disk blocks are $8$ kB in size, and a pointer to a disk block requires $4$ byres. This file system has $12$ direct disk blocks, as well as single, double, and triple indirect disk blocks. What is the maximum size of a file that can be stored in this file system?

$(6)$

$(14\mathrm{.}13,$ p$\mathrm{.}640)$: Explain why logging metadata updates ensures recovery of a file system after a file$-$system crash.