There are several related goals for this assignment:

$$ Implement the Spawn$(),$ Waitpid$(),$ and Exit$()$ system calls. These calls will allow user

processes to create new user processes. Spawn$()$ will involve loading a user program

from a file and then running it$.$

$$ Do some basic keyboard I$/$O$,$ implementing Putchar$()$ and Getchar$()$ for user programs.

$$ Write a simple shell for Minix with support for Spawn$()$ and Waitpid$().$

$$ Defined a shared memory, i$.$e$.$ mailbox, from the parent to the children. The memory

must be shared among all children as you need to implement readers$-$writers

synchronization paradigm.

$$ Write a program and the necessary traps to display a list of all running processes

$($spawned from the shell, and otherwise$).$ This list should include the program name, ID$,$

mode $($user$/$system$)$ and state $($running$,$ ready, waiting, etc.$)$ for each process in the

system. In other words, this program would do the same thing as ps does on Unix. You'll

need at least one new trap to implement this, and I$\text{'}$d suggest two traps $($one to get the list

of process IDs and one to find information about each process$).$ Keep in mind that

returning strings from a trap could be difficult.