$3\mathrm{.}4$ The stm and $1dm$ instructions include an optional $\text{'}!\text{'}$ after the address register. What does it do$?$

$3\mathrm{.}5$ The following $C$ statement declares an array of four integers, and initializes their values to $7,3,21,$ and $10,$ in that order.

int nums $[]=\{7,3,21,10\}$;

$($a$)$ Write the equivalent in GNU ARM assembly.

$($b$)$ Write the ARM assembly instructions to load all four numbers into registers $r,$ r$5,$ r$6,$ and r$9,$ respectively, using:

i$.$ a single $1dm$ instruction, and

ii$.$ four $1dr$ instructions.

$3\mathrm{.}6$ What is the difference between a memory location and a CPU register?

i speciaplly need solution for $3\mathrm{.}4,$ and $3\mathrm{.}5$