diff --git a/src/kernel/scheduler.rs b/src/kernel/scheduler.rs
index 7071fbb..01ad40f 100644
--- a/src/kernel/scheduler.rs
+++ b/src/kernel/scheduler.rs
@@ -3,12 +3,12 @@ use std::rc::Rc;
 
 use crate::utility::list::List;
 use crate::kernel::thread::Thread;
+use super::system::System;
 use super::thread_manager::ThreadManager;
 
 #[derive(PartialEq)]
 pub struct Scheduler {
     ready_list: List<Rc<RefCell<Thread>>>,
-    pub thread_manager: Option<Rc<RefCell<ThreadManager>>> 
 }
 
 impl Scheduler {
@@ -19,7 +19,6 @@ impl Scheduler {
     pub fn new() -> Self {
         Self {
             ready_list: List::new(),
-            thread_manager: Option::None
         }
     }
 
@@ -54,21 +53,16 @@ impl Scheduler {
     /// ## Parameter
     /// 
     /// **next_thread** thread to dispatch to the CPU
-    pub fn switch_to(&mut self, next_thread: Rc<RefCell<Thread>>) {
-        if let Some(tm) = &self.thread_manager {
-            let rc = Rc::clone(&tm);
-            if let Some(old_thread) = tm.borrow_mut().get_g_current_thread() {
-                rc.borrow_mut().thread_save_processor_state(Rc::clone(&old_thread));
-                // old_thread.save_simulator_state();
+    pub fn switch_to(&mut self, system: &mut System, next_thread: Rc<RefCell<Thread>>) {
+        let old_thread = system.get_thread_manager().get_g_current_thread().as_ref().unwrap();
+        system.get_thread_manager().thread_save_processor_state(system, Rc::clone(&old_thread));
+        // old_thread.save_simulator_state();
 
-                if old_thread != &next_thread {
-                    rc.borrow_mut().thread_restore_processor_state(Rc::clone(&next_thread));
-                    // next_thread.restore_simulator_state();
-                    rc.borrow_mut().set_g_current_thread(Option::Some(next_thread));
-                }
-            }
-        } else {
-            panic!("thread manager shouldn't be none");
+        if old_thread != &next_thread {
+            system.get_thread_manager().thread_restore_processor_state(system, Rc::clone(&next_thread));
+            // next_thread.restore_simulator_state();
+            system.get_thread_manager().set_g_current_thread(Option::Some(next_thread));
         }
+    
     }
 }
\ No newline at end of file
diff --git a/src/kernel/synch.rs b/src/kernel/synch.rs
index f5741f7..89df690 100644
--- a/src/kernel/synch.rs
+++ b/src/kernel/synch.rs
@@ -17,8 +17,6 @@ pub struct Semaphore {
     counter:i32,
     /// QUeue of Semaphore waiting to be exucated
     waiting_queue:List<Rc<RefCell<Thread>>>,
-    /// Thread manager which managing threads
-    thread_manager: Rc<RefCell<ThreadManager>>
 
 }
 
@@ -29,8 +27,8 @@ impl Semaphore {
     ///  ### Parameters
     /// - *counter* initial value of counter
     /// - *thread_manager* Thread manager which managing threads
-    pub fn new(counter: i32, thread_manager: Rc<RefCell<ThreadManager>>) -> Semaphore{
-        Semaphore { counter, waiting_queue: List::new(), thread_manager}
+    pub fn new(counter: i32) -> Semaphore{
+        Semaphore { counter, waiting_queue: List::new()}
     }
 
     ///     Decrement the value, and wait if it becomes < 0. Checking the
@@ -87,8 +85,6 @@ pub struct Lock{
     owner: Option<Rc<RefCell<Thread>>>,
     /// The queue of threads waiting for execution
     waiting_queue:List<Rc<RefCell<Thread>>>,
-    /// Thread manager which managing threads
-    thread_manager: Rc<RefCell<ThreadManager>>,
     /// A boolean definig if the lock is free or not
     free: bool
 
@@ -101,8 +97,8 @@ impl Lock {
     ///
     /// ### Parameters
     /// - **thread_manager** Thread manager which managing threads
-    pub fn new(thread_manager: Rc<RefCell<ThreadManager>>) -> Lock {
-        Lock { owner: None, waiting_queue: List::new(), thread_manager, free: true }
+    pub fn new() -> Lock {
+        Lock { owner: None, waiting_queue: List::new(), free: true }
     }
 
     ///    Wait until the lock become free.  Checking the
@@ -192,8 +188,6 @@ pub struct Condition{
 
     /// The queue of threads waiting for execution
     waiting_queue:List<Rc<RefCell<Thread>>>,
-    /// Thread manager which managing threads
-    thread_manager: Rc<RefCell<ThreadManager>>,
     
 }
 
@@ -203,8 +197,8 @@ impl Condition {
     ///
     /// ### Parameters
     /// - *thread_manager* Thread manager which managing threads
-    pub fn new(thread_manager: Rc<RefCell<ThreadManager>>) -> Condition {
-        Condition{ waiting_queue: List::new(), thread_manager }
+    pub fn new() -> Condition {
+        Condition{ waiting_queue: List::new()}
     }
 
     ///  Block the calling thread (put it in the wait queue).
@@ -213,13 +207,18 @@ impl Condition {
     /// ### Parameters
     /// - **current_thread** the current thread
     /// - **machine** the machine where threads are executed
-    pub fn wait(&mut self, current_thread: Rc<RefCell<Thread>>, machine: &mut Machine, system: &mut System) {
-        let old_status = machine.interrupt.set_status(InterruptOff);
+    pub fn wait(&mut self, system: &mut System) {
+        let old_status = system.get_machine().interrupt.set_status(InterruptOff);
 
-        self.waiting_queue.push(Rc::clone(&current_thread));
-        self.thread_manager.borrow_mut().thread_sleep(system, current_thread);
+        match system.get_thread_manager().get_g_current_thread() {
+            Some(thread) => {
+                self.waiting_queue.push(Rc::clone(thread));
+                system.thread_sleep(Rc::clone(thread));
+            },
+            None => unreachable!()
+        }
 
-        machine.interrupt.set_status(old_status);
+        system.get_machine().interrupt.set_status(old_status);
     }
 
     /// Wake up the first thread of the wait queue (if any).
@@ -228,14 +227,14 @@ impl Condition {
     /// ### Parameters
     /// - **machine** the machine where the code is executed
     /// - **scheduler** the scheduler which determine which thread to execute
-    pub fn signal(&mut self, machine: &mut Machine, scheduler: &mut Scheduler) {
-        let old_status = machine.interrupt.set_status(InterruptOff);
+    pub fn signal(&mut self, system: &mut System) {
+        let old_status = system.get_machine().interrupt.set_status(InterruptOff);
 
         if self.waiting_queue.peek() != None {
-            scheduler.ready_to_run(self.waiting_queue.pop().unwrap());
+            system.get_thread_manager().g_scheduler.ready_to_run(self.waiting_queue.pop().unwrap());
         }
 
-        machine.interrupt.set_status(old_status);
+        system.get_machine().interrupt.set_status(old_status);
 
     }
 
@@ -245,13 +244,13 @@ impl Condition {
     /// ### Parameters
     /// - **machine** the machine where the code is executed
     /// - **scheduler** the scheduler which determine which thread to execute
-    pub fn broadcast(&mut self, machine: &mut Machine, scheduler: &mut Scheduler) {
-        let old_status = machine.interrupt.set_status(InterruptOff);
+    pub fn broadcast(&mut self, system: &mut System) {
+        let old_status = system.get_machine().interrupt.set_status(InterruptOff);
 
         while self.waiting_queue.peek() != None {
-            scheduler.ready_to_run(self.waiting_queue.pop().unwrap());
+            system.get_thread_manager().g_scheduler.ready_to_run(self.waiting_queue.pop().unwrap());
         }
-        machine.interrupt.set_status(old_status);
+        system.get_machine().interrupt.set_status(old_status);
 
     }
 
diff --git a/src/kernel/system.rs b/src/kernel/system.rs
index 7383911..6104dc3 100644
--- a/src/kernel/system.rs
+++ b/src/kernel/system.rs
@@ -49,7 +49,7 @@ impl System {
     /// Sets a thread asleep
     /// 
     pub fn thread_sleep(&mut self, thread: Rc<RefCell<Thread>>) {
-        &self.thread_manager.thread_sleep(self, thread);
+        self.thread_manager.thread_sleep(self, thread);
     }
 
     // GETTERS
diff --git a/src/kernel/thread_manager.rs b/src/kernel/thread_manager.rs
index 2d5cc06..5820906 100644
--- a/src/kernel/thread_manager.rs
+++ b/src/kernel/thread_manager.rs
@@ -70,7 +70,7 @@ impl ThreadManager {
         if let Some(next_thread) = next_thread {
             let scheduler = &mut self.g_scheduler;
             scheduler.ready_to_run(thread);
-            scheduler.switch_to(next_thread);
+            scheduler.switch_to(system, next_thread);
         }
         machine.interrupt.set_status(old_status);
     }
@@ -86,7 +86,7 @@ impl ThreadManager {
             machine.interrupt.idle();
             next_thread = self.g_scheduler.find_next_to_run();
         }
-        self.g_scheduler.switch_to(Rc::clone(&next_thread.unwrap()));
+        self.g_scheduler.switch_to(system, Rc::clone(&next_thread.unwrap()));
     }
 
     /// Finish the execution of the thread and prepare its deallocation