diff --git a/.vscode/.ropeproject/config.py b/.vscode/.ropeproject/config.py
new file mode 100644
index 0000000..dee2d1a
--- /dev/null
+++ b/.vscode/.ropeproject/config.py
@@ -0,0 +1,114 @@
+# The default ``config.py``
+# flake8: noqa
+
+
+def set_prefs(prefs):
+    """This function is called before opening the project"""
+
+    # Specify which files and folders to ignore in the project.
+    # Changes to ignored resources are not added to the history and
+    # VCSs.  Also they are not returned in `Project.get_files()`.
+    # Note that ``?`` and ``*`` match all characters but slashes.
+    # '*.pyc': matches 'test.pyc' and 'pkg/test.pyc'
+    # 'mod*.pyc': matches 'test/mod1.pyc' but not 'mod/1.pyc'
+    # '.svn': matches 'pkg/.svn' and all of its children
+    # 'build/*.o': matches 'build/lib.o' but not 'build/sub/lib.o'
+    # 'build//*.o': matches 'build/lib.o' and 'build/sub/lib.o'
+    prefs['ignored_resources'] = ['*.pyc', '*~', '.ropeproject',
+                                  '.hg', '.svn', '_svn', '.git', '.tox']
+
+    # Specifies which files should be considered python files.  It is
+    # useful when you have scripts inside your project.  Only files
+    # ending with ``.py`` are considered to be python files by
+    # default.
+    # prefs['python_files'] = ['*.py']
+
+    # Custom source folders:  By default rope searches the project
+    # for finding source folders (folders that should be searched
+    # for finding modules).  You can add paths to that list.  Note
+    # that rope guesses project source folders correctly most of the
+    # time; use this if you have any problems.
+    # The folders should be relative to project root and use '/' for
+    # separating folders regardless of the platform rope is running on.
+    # 'src/my_source_folder' for instance.
+    # prefs.add('source_folders', 'src')
+
+    # You can extend python path for looking up modules
+    # prefs.add('python_path', '~/python/')
+
+    # Should rope save object information or not.
+    prefs['save_objectdb'] = True
+    prefs['compress_objectdb'] = False
+
+    # If `True`, rope analyzes each module when it is being saved.
+    prefs['automatic_soa'] = True
+    # The depth of calls to follow in static object analysis
+    prefs['soa_followed_calls'] = 0
+
+    # If `False` when running modules or unit tests "dynamic object
+    # analysis" is turned off.  This makes them much faster.
+    prefs['perform_doa'] = True
+
+    # Rope can check the validity of its object DB when running.
+    prefs['validate_objectdb'] = True
+
+    # How many undos to hold?
+    prefs['max_history_items'] = 32
+
+    # Shows whether to save history across sessions.
+    prefs['save_history'] = True
+    prefs['compress_history'] = False
+
+    # Set the number spaces used for indenting.  According to
+    # :PEP:`8`, it is best to use 4 spaces.  Since most of rope's
+    # unit-tests use 4 spaces it is more reliable, too.
+    prefs['indent_size'] = 4
+
+    # Builtin and c-extension modules that are allowed to be imported
+    # and inspected by rope.
+    prefs['extension_modules'] = []
+
+    # Add all standard c-extensions to extension_modules list.
+    prefs['import_dynload_stdmods'] = True
+
+    # If `True` modules with syntax errors are considered to be empty.
+    # The default value is `False`; When `False` syntax errors raise
+    # `rope.base.exceptions.ModuleSyntaxError` exception.
+    prefs['ignore_syntax_errors'] = False
+
+    # If `True`, rope ignores unresolvable imports.  Otherwise, they
+    # appear in the importing namespace.
+    prefs['ignore_bad_imports'] = False
+
+    # If `True`, rope will insert new module imports as
+    # `from <package> import <module>` by default.
+    prefs['prefer_module_from_imports'] = False
+
+    # If `True`, rope will transform a comma list of imports into
+    # multiple separate import statements when organizing
+    # imports.
+    prefs['split_imports'] = False
+
+    # If `True`, rope will remove all top-level import statements and
+    # reinsert them at the top of the module when making changes.
+    prefs['pull_imports_to_top'] = True
+
+    # If `True`, rope will sort imports alphabetically by module name instead
+    # of alphabetically by import statement, with from imports after normal
+    # imports.
+    prefs['sort_imports_alphabetically'] = False
+
+    # Location of implementation of
+    # rope.base.oi.type_hinting.interfaces.ITypeHintingFactory In general
+    # case, you don't have to change this value, unless you're an rope expert.
+    # Change this value to inject you own implementations of interfaces
+    # listed in module rope.base.oi.type_hinting.providers.interfaces
+    # For example, you can add you own providers for Django Models, or disable
+    # the search type-hinting in a class hierarchy, etc.
+    prefs['type_hinting_factory'] = (
+        'rope.base.oi.type_hinting.factory.default_type_hinting_factory')
+
+
+def project_opened(project):
+    """This function is called after opening the project"""
+    # Do whatever you like here!
diff --git a/misc/script.py b/script.py
similarity index 93%
rename from misc/script.py
rename to script.py
index 6152855..1a4001d 100755
--- a/misc/script.py
+++ b/script.py
@@ -17,15 +17,17 @@ def main(argv):
         # Manual configuration:
         configuration = Configuration()
 
+        configuration.cycles_per_ms = 1
+
         configuration.duration = 420 * configuration.cycles_per_ms
 
         # Add tasks:
         configuration.add_task(name="T1", identifier=1, period=7,
                                activation_date=0, wcet=3, deadline=7)
         configuration.add_task(name="T2", identifier=2, period=12,
-                               activation_date=0, wcet=3, deadline=12)
+                               activation_date=0, wcet=3, deadline=8)
         configuration.add_task(name="T3", identifier=3, period=20,
-                               activation_date=0, wcet=5, deadline=20)
+                               activation_date=0, wcet=5, deadline=9)
 
         # Add a processor:
         configuration.add_processor(name="CPU 1", identifier=1)
diff --git a/script_proba.py b/script_proba.py
new file mode 100644
index 0000000..1251b99
--- /dev/null
+++ b/script_proba.py
@@ -0,0 +1,52 @@
+#!/usr/bin/python3
+
+"""
+Example of a script that uses SimSo.
+"""
+
+import sys
+from simso.core import Model
+from simso.configuration import Configuration
+
+
+def main(argv):
+    if len(argv) == 2:
+        # Configuration load from a file.
+        configuration = Configuration(argv[1])
+    else:
+        # Manual configuration:
+        configuration = Configuration()
+
+        configuration.cycles_per_ms = 1
+ 
+        configuration.etm = "pwcet"
+
+        configuration.duration = 100 * configuration.cycles_per_ms
+
+        # Add tasks:
+        configuration.add_task(name="T1", identifier=1,
+                              activation_date=0, pwcet=[(2,0.5), (4,0.5)],pmit=[(5,0.2),(6,0.8)], deadline=6, task_type = "Probabilistic",abort_on_miss=True)
+
+        configuration.add_task(name="T2", identifier=2,
+                              activation_date=0, pwcet=[(3,0.5),(4,0.5)],pmit=[(5,0.5), (7, 0.5)], deadline=7, task_type = "Probabilistic",abort_on_miss=True)
+
+        # Add a processor:
+        configuration.add_processor(name="CPU 1", identifier=1)
+
+        # Add a scheduler:
+        configuration.scheduler_info.filename = "./simso/schedulers/DM_mono.py"
+
+    # Check the config before trying to run it.
+    configuration.check_all()
+
+    # Init a model from the configuration.
+    model = Model(configuration)
+
+    # Execute the simulation.
+    model.run_model()
+
+    # Print logs.
+    for log in model.logs:
+        print(log)
+
+main(sys.argv)
diff --git a/setup.py b/setup.py
index f98b0dd..1d8e34e 100644
--- a/setup.py
+++ b/setup.py
@@ -17,9 +17,10 @@ setup(
         'Topic :: Scientific/Engineering',
         'Development Status :: 5 - Production/Stable'
     ],
+    python_requires='>=3.6',
     packages=find_packages(),
     install_requires=[
-        'SimPy==2.3.1',
+        'SimPy>=4.0.1',
         'numpy>=1.6'
     ],
     long_description="""\
diff --git a/simso/configuration/Configuration.py b/simso/configuration/Configuration.py
index 4c0f2d7..539911e 100644
--- a/simso/configuration/Configuration.py
+++ b/simso/configuration/Configuration.py
@@ -8,6 +8,8 @@ from simso.core.Scheduler import SchedulerInfo
 from simso.core import Scheduler
 from simso.core.Task import TaskInfo
 from simso.core.Processor import ProcInfo
+from simso.generator.task_generator import gen_probabilistic_arrivals
+from simso.generator.task_generator import cdf
 
 from .GenerateConfiguration import generate
 from .parser import Parser
@@ -38,6 +40,7 @@ class Configuration(object):
     of this class will be passed to the constructor of the
     :class:`Model <simso.core.Model.Model>` class.
     """
+
     def __init__(self, filename=None):
         """
         Args:
@@ -279,7 +282,7 @@ class Configuration(object):
 
     def add_task(self, name, identifier, task_type="Periodic",
                  abort_on_miss=True, period=10, activation_date=0,
-                 n_instr=0, mix=0.5, stack_file="", wcet=0, acet=0,
+                 n_instr=0, mix=0.5, stack_file="", wcet=0, acet=0, pwcet=(0, 1.0), pmit=(0, 1.0),
                  et_stddev=0, deadline=10, base_cpi=1.0, followed_by=None,
                  list_activation_dates=[], preemption_cost=0, data=None):
         """
@@ -288,9 +291,14 @@ class Configuration(object):
         if data is None:
             data = dict((k, None) for k in self.task_data_fields)
 
+        if task_type == "Probabilistic":
+            list_activation_dates = gen_probabilistic_arrivals(
+                pmit, activation_date, self.duration, False)
+            pwcet = cdf(pwcet)
+
         task = TaskInfo(name, identifier, task_type, abort_on_miss, period,
                         activation_date, n_instr, mix,
-                        (stack_file, self.cur_dir), wcet, acet, et_stddev,
+                        (stack_file, self.cur_dir), wcet, acet, pwcet, et_stddev,
                         deadline, base_cpi, followed_by, list_activation_dates,
                         preemption_cost, data)
         self.task_info_list.append(task)
diff --git a/simso/configuration/GenerateConfiguration.py b/simso/configuration/GenerateConfiguration.py
index faba105..0af5d39 100644
--- a/simso/configuration/GenerateConfiguration.py
+++ b/simso/configuration/GenerateConfiguration.py
@@ -112,6 +112,7 @@ def generate_tasks(top, task_info_list, fields):
                       'mix': str(task.mix),
                       'WCET': str(task.wcet),
                       'ACET': str(task.acet),
+                      'PWCET': str(task.pwcet),
                       'preemption_cost': str(task.preemption_cost),
                       'et_stddev': str(task.et_stddev)})
         if task.followed_by is not None:
diff --git a/simso/core/Job.py b/simso/core/Job.py
index 4708fd3..12afdbc 100644
--- a/simso/core/Job.py
+++ b/simso/core/Job.py
@@ -44,6 +44,7 @@ class Job(Process):
         self._monitor = monitor
         self._etm = etm
         self._was_running_on = task.cpu
+        self._wcet = task.wcet
 
         self._on_activate()
 
@@ -106,7 +107,8 @@ class Job(Process):
         self._monitor.observe(JobEvent(self, JobEvent.ABORTED))
         self._task.end_job(self)
         self._task.cpu.terminate(self)
-        self._sim.logger.log("Job " + str(self.name) + " aborted! ret:" + str(self.ret))
+        self._sim.logger.log("Job " + str(self.name) +
+                             " aborted! ret:" + str(self.ret))
 
     def is_running(self):
         """
@@ -243,7 +245,11 @@ class Job(Process):
         Worst-Case Execution Time in milliseconds.
         Equivalent to ``self.task.wcet``.
         """
-        return self._task.wcet
+        return self._wcet
+
+    @wcet.setter
+    def wcet(self, value):
+        self._wcet = value
 
     @property
     def activation_date(self):
@@ -314,3 +320,11 @@ class Job(Process):
 
             else:
                 self.interruptReset()
+
+
+class SequentialJob(Job):
+    pass
+
+
+class ParallelJob(Job):
+    pass
diff --git a/simso/core/Model.py b/simso/core/Model.py
index de61b0e..3f58584 100644
--- a/simso/core/Model.py
+++ b/simso/core/Model.py
@@ -7,6 +7,7 @@ from simso.core.Timer import Timer
 from simso.core.etm import execution_time_models
 from simso.core.Logger import Logger
 from simso.core.results import Results
+import SimPy as SPPc
 
 
 class Model(Simulation):
@@ -26,6 +27,7 @@ class Model(Simulation):
 
         Methods:
         """
+        print(SPPc.__version__)
         Simulation.__init__(self)
         self._logger = Logger(self)
         task_info_list = configuration.task_info_list
diff --git a/simso/core/Task.py b/simso/core/Task.py
index da5ad2d..a37cfdf 100644
--- a/simso/core/Task.py
+++ b/simso/core/Task.py
@@ -18,7 +18,7 @@ class TaskInfo(object):
     """
 
     def __init__(self, name, identifier, task_type, abort_on_miss, period,
-                 activation_date, n_instr, mix, stack_file, wcet, acet,
+                 activation_date, n_instr, mix, stack_file, wcet, acet, pwcet,
                  et_stddev, deadline, base_cpi, followed_by,
                  list_activation_dates, preemption_cost, data):
         """
@@ -33,6 +33,7 @@ class TaskInfo(object):
         :type stack_file: str
         :type wcet: float
         :type acet: float
+        :type pwcet: list
         :type et_stddev: float
         :type deadline: float
         :type base_cpi: float
@@ -62,6 +63,7 @@ class TaskInfo(object):
         self.list_activation_dates = list_activation_dates
         self.data = data
         self.preemption_cost = preemption_cost
+        self._pwcet = pwcet
 
     @property
     def csdp(self):
@@ -316,7 +318,7 @@ class PTask(GenericTask):
                               self._sim.cycles_per_ms)
 
         while True:
-            #print self.sim.now(), "activate", self.name
+            # print self.sim.now(), "activate", self.name
             self.create_job()
             yield hold, self, int(self.period * self._sim.cycles_per_ms)
 
@@ -341,13 +343,38 @@ class SporadicTask(GenericTask):
         return self._task_info.list_activation_dates
 
 
+class ProbabilisticTask(GenericTask):
+    """
+    Probabilistic Task process. Inherits from :class:`GenericTask`. The jobs are
+    created using a list of probabilistic activation times.
+    """
+    fields = ['list_activation_dates', 'deadline', 'pwcet', 'pmit']
+
+    def execute(self):
+
+        self._init()
+        for ndate in self.list_activation_dates:
+            yield hold, self, int(ndate * self._sim.cycles_per_ms) \
+                - self._sim.now()
+            self.create_job()
+
+    @property
+    def list_activation_dates(self):
+        return self._task_info.list_activation_dates
+
+    @property
+    def pwcet(self):
+        return self._task_info._pwcet
+
+
 task_types = {
     "Periodic": PTask,
     "APeriodic": ATask,
-    "Sporadic": SporadicTask
+    "Sporadic": SporadicTask,
+    "Probabilistic": ProbabilisticTask
 }
 
-task_types_names = ["Periodic", "APeriodic", "Sporadic"]
+task_types_names = ["Periodic", "APeriodic", "Sporadic", "Probabilistic"]
 
 
 def Task(sim, task_info):
@@ -355,5 +382,4 @@ def Task(sim, task_info):
     Task factory. Return and instantiate the correct class according to the
     task_info.
     """
-
     return task_types[task_info.task_type](sim, task_info)
diff --git a/simso/core/etm/PWCET.py b/simso/core/etm/PWCET.py
new file mode 100644
index 0000000..1d8099f
--- /dev/null
+++ b/simso/core/etm/PWCET.py
@@ -0,0 +1,52 @@
+import random
+from simso.core.etm.AbstractExecutionTimeModel \
+    import AbstractExecutionTimeModel
+
+
+class PWCET(AbstractExecutionTimeModel):
+    def __init__(self, sim, _):
+        self.sim = sim
+        self.executed = {}
+        self.on_execute_date = {}
+
+    def init(self):
+        pass
+
+    def update_executed(self, job):
+        if job in self.on_execute_date:
+            self.executed[job] += (self.sim.now() - self.on_execute_date[job]
+                                   ) * job.cpu.speed
+
+            del self.on_execute_date[job]
+
+    def on_activate(self, job):
+        self.executed[job] = 0
+        job.wcet = next(x[0] for x in job.task.pwcet if random.uniform(
+            0, 1) <= x[1]) * self.sim.cycles_per_ms
+
+    def on_execute(self, job):
+        self.on_execute_date[job] = self.sim.now()
+
+    def on_preempted(self, job):
+        self.update_executed(job)
+
+    def on_terminated(self, job):
+        self.update_executed(job)
+
+    def on_abort(self, job):
+        self.update_executed(job)
+
+    def get_executed(self, job):
+        if job in self.on_execute_date:
+            c = (self.sim.now() - self.on_execute_date[job]) * job.cpu.speed
+        else:
+            c = 0
+        return self.executed[job] + c
+
+    def get_ret(self, job):
+        wcet_cycles = int(job.wcet * self.sim.cycles_per_ms)
+        return int(wcet_cycles - self.get_executed(job))
+
+    def update(self):
+        for job in list(self.on_execute_date.keys()):
+            self.update_executed(job)
diff --git a/simso/core/etm/__init__.py b/simso/core/etm/__init__.py
index 14329a4..32550bc 100644
--- a/simso/core/etm/__init__.py
+++ b/simso/core/etm/__init__.py
@@ -1,5 +1,6 @@
 from .WCET import WCET
 from .ACET import ACET
+from .PWCET import PWCET
 from .CacheModel import CacheModel
 from .FixedPenalty import FixedPenalty
 
@@ -7,12 +8,14 @@ execution_time_models = {
     'wcet': WCET,
     'acet': ACET,
     'cache': CacheModel,
-    'fixedpenalty': FixedPenalty
+    'fixedpenalty': FixedPenalty,
+    'pwcet': PWCET
 }
 
 execution_time_model_names = {
     'WCET': 'wcet',
     'ACET': 'acet',
     'Cache Model': 'cache',
-    'Fixed Penalty': 'fixedpenalty'
+    'Fixed Penalty': 'fixedpenalty',
+    'Probabilistic WCET': 'pwcet'
 }
diff --git a/simso/generator/task_generator.py b/simso/generator/task_generator.py
index 1fad270..1104613 100755
--- a/simso/generator/task_generator.py
+++ b/simso/generator/task_generator.py
@@ -5,6 +5,7 @@ Tools for generating task sets.
 import numpy as np
 import random
 import math
+from functools import reduce
 
 
 def UUniFastDiscard(n, u, nsets):
@@ -68,7 +69,7 @@ def StaffordRandFixedSum(n, u, nsets):
     if n < u:
         return None
 
-    #deal with n=1 case
+    # deal with n=1 case
     if n == 1:
         return np.tile(np.array([u]), [nsets, 1])
 
@@ -113,8 +114,8 @@ def StaffordRandFixedSum(n, u, nsets):
 
     x[n - 1, ...] = sm + pr * s
 
-    #iterated in fixed dimension order but needs to be randomised
-    #permute x row order within each column
+    # iterated in fixed dimension order but needs to be randomised
+    # permute x row order within each column
     for i in range(0, nsets):
         x[..., i] = x[np.random.permutation(n), i]
 
@@ -218,10 +219,11 @@ def next_arrival_poisson(period):
     return -math.log(1.0 - random.random()) * period
 
 
-def gen_arrivals(period, min_, max_, round_to_int=False):
-    def trunc(x, p):
-        return int(x * 10 ** p) / float(10 ** p)
+def trunc(x, p):
+    return int(x * 10 ** p) / float(10 ** p)
 
+
+def gen_arrivals(period, min_, max_, round_to_int=False):
     dates = []
     n = min_ - period
     while True:
@@ -236,6 +238,28 @@ def gen_arrivals(period, min_, max_, round_to_int=False):
     return dates
 
 
+def cdf(tuple_array):
+    sorted_tuples = sorted(tuple_array, key=lambda x: x[0])
+    return [reduce(lambda x, y: (y[0], x[1]+y[1]), sorted_tuples[:i+1]) for i in range(0, len(sorted_tuples))]
+
+
+def gen_probabilistic_arrivals(pmit, min_, max_, round_to_int=False):
+    dates = [min_]
+    cdf_mit = cdf(pmit)
+
+    n = 0
+    while True:
+        n += next(x[0] for x in cdf_mit if random.random() < x[1])
+        if round_to_int:
+            n = int(round(n))
+        else:
+            n = trunc(n, 6)
+        if n > max_:
+            break
+        dates.append(n)
+    return dates
+
+
 def gen_periods_loguniform(n, nsets, min_, max_, round_to_int=False):
     """
     Generate a list of `nsets` sets containing each `n` random periods using a
diff --git a/simso/schedulers/DM_mono.py b/simso/schedulers/DM_mono.py
new file mode 100644
index 0000000..7c0aafd
--- /dev/null
+++ b/simso/schedulers/DM_mono.py
@@ -0,0 +1,27 @@
+"""
+Deadline Monotonic algorithm for uniprocessor architectures.
+"""
+from simso.core import Scheduler
+from simso.schedulers import scheduler
+
+@scheduler("simso.schedulers.DM_mono")
+class DM_mono(Scheduler):
+    def init(self):
+        self.ready_list = []
+
+    def on_activate(self, job):
+        self.ready_list.append(job)
+        job.cpu.resched()
+
+    def on_terminated(self, job):
+        self.ready_list.remove(job)
+        job.cpu.resched()
+
+    def schedule(self, cpu):
+        if self.ready_list:
+            # job with the highest priority based on deadline
+            job = min(self.ready_list, key=lambda x: x.task.deadline)
+        else:
+            job = None
+
+        return (job, cpu)