diff --git a/src/kernel/mod.rs b/src/kernel/mod.rs
index f1abafa..1988e43 100644
--- a/src/kernel/mod.rs
+++ b/src/kernel/mod.rs
@@ -4,4 +4,5 @@ pub mod scheduler;
 pub mod mgerror;
 pub mod system;
 mod ucontext;
-mod synch;
\ No newline at end of file
+mod synch;
+mod thread_manager;
\ No newline at end of file
diff --git a/src/kernel/system.rs b/src/kernel/system.rs
index 8ef7ecb..863bdc2 100644
--- a/src/kernel/system.rs
+++ b/src/kernel/system.rs
@@ -1,12 +1,6 @@
-use std::rc::Rc;
-use crate::{
-    kernel::{
-        thread::Thread,
-        scheduler::Scheduler
-    },
-    utility::list::List,
-    simulator::machine::Machine
-};
+use crate::simulator::machine::Machine;
+
+use super::thread_manager::ThreadManager;
 
 /// # System
 /// 
@@ -19,26 +13,24 @@ use crate::{
 /// - The thread to be destroyed next
 /// - The scheduler which acts upon these threads
 #[derive(PartialEq)]
-pub struct System {
+pub struct System<'a> {
     g_machine: Machine,
-    g_current_thread: Option<Thread>,
-    g_thread_to_be_destroyed: Option<Thread>,
-    g_alive: List<Rc<Thread>>,
-    g_scheduler: Scheduler
+    thread_manager: ThreadManager<'a>
 }
 
-impl System {
+impl<'a> System<'a> {
 
     /// System constructor
-    pub fn new(machine: Machine, scheduler: Scheduler) -> Self {
+    pub fn new(machine: Machine) -> System<'a> {
         Self {
             g_machine: machine,
-            g_current_thread: None,
-            g_thread_to_be_destroyed: None,
-            g_alive: List::new(),
-            g_scheduler: scheduler
+            thread_manager: ThreadManager::new()
         }
-    } 
+    }
+
+    pub fn freeze(&'a mut self) {
+        self.thread_manager.system.set(Option::Some(self));
+    }
 
     // GETTERS
 
@@ -49,28 +41,6 @@ impl System {
         &mut self.g_machine
     }
 
-    /// Currently running thread
-    pub fn get_g_current_thread(&mut self) -> &mut Option<Thread> {
-        &mut self.g_current_thread
-    }
-
-    /// Thread to be destroyed by [...]
-    /// 
-    /// TODO: Finish the comment with the relevant value
-    pub fn get_g_thread_to_be_destroyed(&mut self) -> &mut Option<Thread> {
-        &mut self.g_thread_to_be_destroyed
-    }
-
-    /// List of alive threads
-    pub fn get_g_alive(&mut self) -> &mut List<Rc<Thread>> {
-        &mut self.g_alive
-    }
-
-    /// Current scheduler
-    pub fn g_scheduler(&mut self) -> &mut Scheduler {
-        &mut self.g_scheduler
-    }
-
     // Setters
 
     /// Assign a machine to the system
@@ -78,21 +48,6 @@ impl System {
         self.g_machine = machine
     }
 
-    /// Set currently running thread
-    pub fn set_g_current_thread(&mut self, thread: Option<Thread>) {
-        self.g_current_thread = thread
-    }
-
-    /// Set thread to be destroyed next
-    pub fn set_g_thread_to_be_destroyed(&mut self, thread: Option<Thread>) {
-        self.g_thread_to_be_destroyed = thread
-    }
-
-    /// Set Scheduler which will manage the threads
-    pub fn set_g_scheduler(&mut self, scheduler: Scheduler) {
-        self.g_scheduler = scheduler
-    }
-
 }
 
 #[derive(PartialEq)]
diff --git a/src/kernel/thread.rs b/src/kernel/thread.rs
index 3ffbba6..68bc7c9 100644
--- a/src/kernel/thread.rs
+++ b/src/kernel/thread.rs
@@ -1,6 +1,4 @@
-use std::{sync::Arc, rc::Rc};
-
-use super::{process::Process, mgerror::ErrorCode, system::{ObjectType, System}, ucontext::UContextT};
+use super::{process::Process, system::ObjectType};
 use crate::{simulator::machine::{NUM_INT_REGS, NUM_FP_REGS, STACK_REG}};
 
 const SIMULATORSTACKSIZE: usize = 32 * 1024;
@@ -16,18 +14,17 @@ struct ThreadContext {
 #[derive(PartialEq)]
 pub struct Thread {
     name: String,
-    process: Option<Process>,
+    pub process: Option<Process>,
     // simulation_context: UContextT,
     thread_context: ThreadContext,
     stack_pointer: i32,
-    object_type: ObjectType,
-    system: Rc<System>
+    object_type: ObjectType
 }
 
 impl Thread {
 
     /// Thread constructor
-    pub fn new(name: String, system: Rc<System>) -> Self {
+    pub fn new(name: String) -> Self {
         Self {
             name,
             process: None,
@@ -39,31 +36,16 @@ impl Thread {
             },
             stack_pointer: 0,
             object_type: ObjectType::ThreadType,
-            system
         }
     }
 
-    /// Start a thread, attaching it to a process
-    pub fn start(mut self, owner: Process, func: i64, arg: i64) -> Result<(), ErrorCode> {
-        self.process = Option::Some(owner);
-        let ptr = 0; // todo addrspace
-        self.init_thread_context(func, ptr, arg);
-        let base_stack_addr: [i8; SIMULATORSTACKSIZE] = [0; SIMULATORSTACKSIZE]; // todo AllocBoundedArray
-        self.init_simulator_context(base_stack_addr);
-        self.process.as_mut().unwrap().num_thread += 1;
-        let this = Rc::new(self);
-        self.system.get_g_alive().push(Rc::clone(&this));
-        self.system.g_scheduler().ready_to_run(Rc::clone(&this));
-        Result::Ok(())
-    }
-
-    fn init_thread_context(&mut self, initial_pc_reg: i64, initial_sp: i64, arg: i64) {
+    pub fn init_thread_context(&mut self, initial_pc_reg: i64, initial_sp: i64, arg: i64) {
         self.thread_context.pc = initial_pc_reg;
         self.thread_context.int_registers[10] = arg;
         self.thread_context.int_registers[STACK_REG] = initial_sp;
     }
 
-    fn init_simulator_context(&self, base_stack_addr: [i8; SIMULATORSTACKSIZE]) {
+    pub fn init_simulator_context(&self, base_stack_addr: [i8; SIMULATORSTACKSIZE]) {
         // let res = self.simulation_context.get_context();
         // if res != 0 {
         //     panic!("getcontext returns non-zero value {}", res);
@@ -78,20 +60,6 @@ impl Thread {
         // self.simulation_context.stackBottom[0] = STACK_FENCEPOST;
     }
 
-    /// Wait for another thread to finish its execution
-    pub fn join(&self, id_thread: Rc<Thread>) {
-        while self.system.get_g_alive().contains(&Rc::clone(&id_thread)) {
-            self.t_yield();
-        }
-    }
-
-    /// Relinquish the CPU if any other thread is runnable.
-    /// 
-    /// Cannot use yield as a function name -> reserved name in rust
-    pub fn t_yield(&self) {
-        todo!();
-    }
-
     /// Put the thread to sleep and relinquish the processor
     pub fn sleep(&self) {
         todo!();
diff --git a/src/kernel/thread_manager.rs b/src/kernel/thread_manager.rs
new file mode 100644
index 0000000..28e5eaa
--- /dev/null
+++ b/src/kernel/thread_manager.rs
@@ -0,0 +1,95 @@
+use std::{rc::Rc, cell::Cell};
+
+use crate::utility::list::List;
+
+use super::{scheduler::Scheduler, thread::Thread, system::System, mgerror::ErrorCode, process::Process};
+
+const SIMULATORSTACKSIZE: usize = 32 * 1024;
+
+#[derive(PartialEq)]
+pub struct ThreadManager<'a> {
+    pub g_current_thread: Option<Thread>,
+    pub g_thread_to_be_destroyed: Option<Thread>,
+    pub g_alive: List<Rc<Thread>>,
+    pub g_scheduler: Scheduler,
+    pub system: Cell<Option<&'a System<'a>>>
+}
+
+impl<'a> ThreadManager<'a> {
+
+    pub fn new() -> Self {
+        Self { 
+            g_current_thread: Option::None, 
+            g_thread_to_be_destroyed: Option::None, 
+            g_alive: List::new(),
+            g_scheduler: Scheduler::new(), 
+            system: Cell::new(None)
+        }
+    }
+
+    /// Start a thread, attaching it to a process
+    pub fn start_thread(&mut self, thread: &mut Thread, owner: Process, func_pc: i64, argument: i64) -> Result<(), ErrorCode> {
+        thread.process = Option::Some(owner);
+        let ptr = 0; // todo addrspace
+        thread.init_thread_context(func_pc, ptr, argument);
+        let base_stack_addr: [i8; SIMULATORSTACKSIZE] = [0; SIMULATORSTACKSIZE]; // todo AllocBoundedArray
+        thread.init_simulator_context(base_stack_addr);
+        thread.process.as_mut().unwrap().num_thread += 1;
+        let thread_m = Rc::new(thread);
+        // self.get_g_alive().push(Rc::clone(thread));
+        // self.g_scheduler().ready_to_run(Rc::clone(&thread));
+        Result::Ok(())
+    }
+
+    /// Wait for another thread to finish its execution
+    pub fn thread_join(&mut self, id_thread: Rc<Thread>) {
+        while self.get_g_alive().contains(&Rc::clone(&id_thread)) {
+            self.thread_yield();
+        }
+    }
+
+    /// Relinquish the CPU if any other thread is runnable.
+    /// 
+    /// Cannot use yield as a function name -> reserved name in rust
+    pub fn thread_yield(&mut self) {
+        todo!();
+    }
+
+    /// Currently running thread
+    pub fn get_g_current_thread(&mut self) -> &mut Option<Thread> {
+        &mut self.g_current_thread
+    }
+
+    /// Thread to be destroyed by [...]
+    /// 
+    /// TODO: Finish the comment with the relevant value
+    pub fn get_g_thread_to_be_destroyed(&mut self) -> &mut Option<Thread> {
+        &mut self.g_thread_to_be_destroyed
+    }
+
+    /// List of alive threads
+    pub fn get_g_alive(&mut self) -> &mut List<Rc<Thread>> {
+        &mut self.g_alive
+    }
+
+    /// Current scheduler
+    pub fn g_scheduler(&mut self) -> &mut Scheduler {
+        &mut self.g_scheduler
+    }
+
+    /// Set currently running thread
+    pub fn set_g_current_thread(&mut self, thread: Option<Thread>) {
+        self.g_current_thread = thread
+    }
+
+    /// Set thread to be destroyed next
+    pub fn set_g_thread_to_be_destroyed(&mut self, thread: Option<Thread>) {
+        self.g_thread_to_be_destroyed = thread
+    }
+
+    /// Set Scheduler which will manage the threads
+    pub fn set_g_scheduler(&mut self, scheduler: Scheduler) {
+        self.g_scheduler = scheduler
+    }
+
+}
\ No newline at end of file
diff --git a/src/kernel/ucontext.rs b/src/kernel/ucontext.rs
index 16c29f1..567d144 100644
--- a/src/kernel/ucontext.rs
+++ b/src/kernel/ucontext.rs
@@ -1,5 +1,5 @@
 
-use std::mem::MaybeUninit;
+// use std::mem::MaybeUninit;
 
 /// Safe wrapper for ucontext_t struct of linux-gnu libc
 /// 
diff --git a/src/main.rs b/src/main.rs
index f703804..a19b258 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -2,15 +2,11 @@ mod simulator;
 mod kernel;
 pub mod utility;
 
-use kernel::{
-    scheduler::Scheduler,
-    system::System
-};
+use kernel::system::System;
 use simulator::machine::Machine;
 use simulator::mem_cmp;
 
 fn main() {
     let machine = Machine::_init_machine();
-    let scheduler = Scheduler::new();
-    let system = System::new(machine, scheduler);
+    let _system = System::new(machine);
 }