User programs such as hello and ugrep calls custom system calls "print", "readline", and "getarg". However, you wrote the corresponding function body in "do_print", "do_readline", and "do_getarg". Answer the following questions which relate to how the custom system calls ends up executing the code in "do_XXX" functions.

(1) What information does void *vector[] store?

(2) How does this vector gets pinned to a fixed address in the memory?