I literally don't get this and the previous expert's code didn't work. The screenshots contain the instructions and the tests the program must pass $($I$\text{'}$ll be thrilled if I end up with $60\%$ or more$).$

I$\text{'}$m not sure if you need the content of the other three Python files to make this work but here's how the Operating system code looks like $($the one I actually need to modify$)$:

from typing import Optional

from ram import RAM

from process import Process

from pageregisters import PageRegisters

# $===========================================================================$

# Operating System Memory Management

# $===========================================================================$

#

# InvalidAddress$($Exception$)-$ does nothing, but program will crash with

# an appropriate error

# NotImplemented$($Exception$)-$ Catches the error that a function was called that has not been written yet

# page$\_$fault$($self$,$v$\_$addr$)-$ called when the MMU accesses a page register that is set to None

# load$\_$process$($self$,$process$)-$ a process is being loaded

#

#

class InvalidAddress$($Exception$)$:

pass

class OS:

# $-------------------------------------------------------------$

# constructor

# $-------------------------------------------------------------$

def $\_\_$init$\_\_($self$,$ ram: RAM, page$\_$registers: PageRegisters$)$:

# $---------------------------------------------------------$

# put whatever other data you want need here

# $---------------------------------------------------------$

# $---------------------------------------------------------$

# every OS must have access to the ram

# $---------------------------------------------------------$

# to load data into ram...

# 'self.ram.set$\_$data$($ physical$\_$address, value $)\text{'}$

self.ram: RAM $=$ ram

# $---------------------------------------------------------$

# Divide the RAM into frames

# $---------------------------------------------------------$

self.ram$\_$frames $=[$None$]*(($self$.$ram.max$\_$addr $+1)//$ page$\_$registers.page$\_$size$)$

# $---------------------------------------------------------$

# every OS must have access to the page$\_$registers

# $---------------------------------------------------------$

# to set a specific frame number for a given page

# 'self.page$\_$registers.set$\_$frame$\_$number$($page$\_$number,frame$\_$number$)\text{'}$

# to get the frame$\_$number from the page registers for a specific page

# 'frame$\_$number $=$ self.page$\_$registers.get$\_$frame$\_$number$($page$\_$number$)\text{'}$

self.page$\_$registers: PageRegisters $=$ page$\_$registers

# page size $($or frame size$)$

self.page$\_$size $=$ page$\_$registers.page$\_$size

# $---------------------------------------------------------$

# total number of frames available to the RAM

# $---------------------------------------------------------$

self.num$\_$frames$\_$in$\_$ram $=$ len$($self$.$ram$\_$frames$)$

# $---------------------------------------------------------$

# which process is currently running

# $---------------------------------------------------------$

self.current$\_$process: Optional$[$Process$]=$ None

# $-------------------------------------------------------------$

# os deals with invalid address complaint from mmu

# you must load the appropriate data from the process into

# the ram, and update page registers accordingly

# $...$ other information may also need to be saved

# $-------------------------------------------------------------$

def page$\_$fault$($self$,$ v$\_$addr$)$:

$"""$handles the mmu page faults"""

# $-------------------------------------------------------------$

# new processes is loaded

# NOTE: each process has the properties:

# pid $->$ uniquely identify each process $($integer$)$

# entry$\_$point $->$ which address is the location of the first

# size $->$ the size of the process

# $-------------------------------------------------------------$

def load$\_$process$($self$,$ process$\_$object$)$:

$"""$load a new process"""