diff --git a/.vscode/settings.json b/.vscode/settings.json
index 7a230e1..56a0c54 100644
--- a/.vscode/settings.json
+++ b/.vscode/settings.json
@@ -3,5 +3,6 @@
         "src"
     ],
     "python.testing.unittestEnabled": false,
-    "python.testing.pytestEnabled": true
+    "python.testing.pytestEnabled": true,
+    "python.REPL.enableREPLSmartSend": false
 }
\ No newline at end of file
diff --git a/src/cpu.py b/src/cpu.py
index 3d57789..eb6132e 100644
--- a/src/cpu.py
+++ b/src/cpu.py
@@ -1,13 +1,6 @@
 import time
 
 class CPU:
-    _instance = None
-
-    def __new__(cnt):
-        if not cnt._instance:
-            cnt._instance = super().__new__(cnt)
-        return cnt._instance
-
     def setOS(self, os):
         self.os = os
 
diff --git a/src/operatingSystem.py b/src/operatingSystem.py
index fdcd916..53c6337 100644
--- a/src/operatingSystem.py
+++ b/src/operatingSystem.py
@@ -4,37 +4,47 @@
 class OS:
     _instance = None
 
-    def __new__(cls, cpu, pAlgorithm):
+    def __new__(cls, pAlgorithm):
         if not cls._instance:
             cls._instance = super().__new__(cls)
     
         cls.blockedProcesses = []
         cls.numberOfProcesses = 0
-        cls.cpu = cpu
         cls.cpuScheduler = CPUScheduler(pAlgorithm)
         
         return cls._instance
 
     def createProcess(self, proc):
+        self.getSys().mutex.acquire()
         print("Process [", proc.id, "] is created.", sep='')
         self.cpuScheduler.putProcess(proc)
+        self.getSys().mutex.release()
 
     def hasProcesses(self):
         return self.numberOfProcesses + self.cpuScheduler.getNumberOfProcesses() > 0
     
     def getProcess(self):
+        self.sys.mutex.aquire()
         for proceess in self.blockedProcesses:
             if proceess.wakeTime <= time.time():
                 self.blockedProcesses.remove(proceess)
                 self.numberOfProcesses -= 1
                 self.cpuScheduler.putProcess(proceess)
-        return self.cpuScheduler.getProcess()
+        
+        proc = self.cpuScheduler.getProcess()
+        self.getSystem().mutex.release()
+        return proc
     
     def sleep(self, proc):
+        self.getSystem().mutex.acquire()
         self.blockedProcesses.append(proc)
         self.numberOfProcesses += 1
         proc.wakeTime = time.time() + proc.sleepInterval
+        self.getSystem().mutex.release()
 
     def finishProcess(self, proc):
         print("Process [", proc.id, "] is finished.", sep='')
+
+    def getSystem(sys):
+        return sys
     
\ No newline at end of file
diff --git a/src/sanbox.py b/src/sanbox.py
index 5f5e2aa..9e06851 100644
--- a/src/sanbox.py
+++ b/src/sanbox.py
@@ -7,7 +7,7 @@
 spf = ShortestProcessFirst()
 
 cpu = CPU()
-os = OS(cpu, fcfs)
+os = OS(fcfs)
 cpu.setOS(os)
 
 #process1 = Process(5, 10, 1)
diff --git a/src/system.py b/src/system.py
new file mode 100644
index 0000000..ade81ab
--- /dev/null
+++ b/src/system.py
@@ -0,0 +1,35 @@
+from operatingSystem import OS
+from cpu import CPU
+from algorithmPlanner import *
+import threading
+import threading
+
+class System:
+    _instance = None
+
+    def __new__(cnt):
+        if not cnt._instance:
+            cnt._instance = super().__new__(cnt)
+        return cnt._instance
+
+    def __init__(self, n = 1):
+        self.mutex = threading.Lock()
+        self.cpu = [CPU() for _ in range(5)]
+        self.os = OS(FirstComeFirstServe())
+        
+        for i in range(n):
+            self.cpu[i].setOS(self.os)
+            t = threading.Thread(target=self.cpu[i].run)
+            self.threads.append(t)
+
+    def startThreads(self):
+        for thread in self.threads:
+            thread.start()
+        
+        self.joinThreads()
+    
+    def joinThreads(self):  
+        for thread in self.threads:
+            thread.join()
+
+    
\ No newline at end of file