diff --git a/src/kernel/exception.rs b/src/kernel/exception.rs
new file mode 100644
index 0000000..a62042d
--- /dev/null
+++ b/src/kernel/exception.rs
@@ -0,0 +1,60 @@
+use crate::simulator::machine::{ExceptionType, Machine};
+
+
+pub const SC_HALT: u8 =	0;
+pub const SC_EXIT: u8 =	1;
+pub const SC_EXEC: u8 =	2;
+pub const SC_JOIN: u8 =	3;
+pub const SC_CREATE: u8 = 4;
+pub const SC_OPEN: u8 =	5;
+pub const SC_READ: u8 =	6;
+pub const SC_WRITE: u8 = 7;
+pub const SC_SEEK: u8 = 8;
+pub const SC_CLOSE: u8 = 9;
+pub const SC_NEW_THREAD: u8 = 10;
+pub const SC_YIELD: u8 =	 11;
+pub const SC_PERROR: u8 = 12;
+pub const SC_P: u8 = 13;
+pub const SC_V: u8 = 14;
+pub const SC_SEM_CREATE: u8 = 15 ;
+pub const SC_SEM_DESTROY: u8 =   16;
+pub const SC_LOCK_CREATE: u8 =	 17 ;
+pub const SC_LOCK_DESTROY: u8 =	 18 ;
+pub const SC_LOCK_ACQUIRE: u8 =	 19 ;
+pub const SC_LOCK_RELEASE: u8 =	 20 ;
+pub const SC_COND_CREATE: u8 =	 21 ;
+pub const SC_COND_DESTROY: u8 =	 22 ;
+pub const SC_COND_WAIT: u8 =	 23 ;
+pub const SC_COND_SIGNAL: u8 =	 24;
+pub const SC_COND_BROADCAST: u8 = 25;
+pub const SC_TTY_SEND: u8 =	 26;
+pub const SC_TTY_RECEIVE: u8 =	 27;
+pub const SC_MKDIR: u8 =	 28;
+pub const SC_RMDIR: u8 =	 29;
+pub const SC_REMOVE: u8 =        30;
+pub const SC_FSLIST: u8 =        31;
+pub const SC_SYS_TIME: u8 =	 32 ;
+pub const SC_MMAP: u8 =		 33;
+pub const SC_DEBUG: u8 =         34;
+
+
+pub fn call(exception: ExceptionType, machine: &Machine) {
+
+    match exception {
+        ExceptionType::NoException => todo!(),
+        ExceptionType::SyscallException => syscall(machine),
+        ExceptionType::PagefaultException => todo!(),
+        ExceptionType::ReadOnlyException => todo!(),
+        ExceptionType::BusErrorException => todo!(),
+        ExceptionType::AddressErrorException => todo!(),
+        ExceptionType::OverflowException => todo!(),
+        ExceptionType::IllegalInstrException => todo!(),
+        ExceptionType::NumExceptionTypes => todo!(),
+    }
+}
+
+fn syscall(machine: &Machine) {
+    let call_type = machine.read_int_register(17);
+
+    todo!()
+}
\ No newline at end of file
diff --git a/src/kernel/mod.rs b/src/kernel/mod.rs
index 67a43cb..7081829 100644
--- a/src/kernel/mod.rs
+++ b/src/kernel/mod.rs
@@ -4,4 +4,5 @@ pub mod mgerror;
 pub mod system;
 mod ucontext;
 mod synch;
-mod thread_manager;
\ No newline at end of file
+mod thread_manager;
+pub mod exception;
\ No newline at end of file
diff --git a/src/simulator/machine.rs b/src/simulator/machine.rs
index d54ce8f..0b470ec 100644
--- a/src/simulator/machine.rs
+++ b/src/simulator/machine.rs
@@ -23,6 +23,10 @@ use crate::simulator::{
 	register::*
 };
 
+use crate::kernel::{
+	exception
+};
+
 /// # Exceptions
 /// 
 /// Textual names of the exceptions that can be generated by user program
@@ -48,6 +52,16 @@ pub enum ExceptionType {
 	NumExceptionTypes
 }
 
+/// # Machine Status
+/// 
+/// The machine can be running kernel code (SystemMode), user code (UserMode), 
+/// or there can be no running thread if the ready list is empty (IdleMode). 
+pub enum MachineStatus {
+	IdleMode,
+	SystemMode,
+	UserMode
+}
+
 /// ID of the stack register
 pub const STACK_REG: usize = 2;
 /// Number of available Integer registers
@@ -78,9 +92,12 @@ pub struct Machine {
 	/// Debug data
 	pub registers_trace : String, // for tests
 	/// todo: document Interrupts
-	pub interrupt: Interrupt
+	pub interrupt: Interrupt,
 	// futur taille à calculer int memSize = g_cfg->NumPhysPages * g_cfg->PageSize;
 	//creer une struct cfg(configuration) qui s'initialise avec valeur dans un fichier cfg
+	
+	/// Current machine status
+	pub status: MachineStatus
 }
 
 
@@ -105,7 +122,8 @@ impl Machine {
 			main_memory : vec![0_u8; MEM_SIZE],
 			shiftmask,
 			interrupt: Interrupt::new(),
-			registers_trace : String::from("")
+			registers_trace : String::from(""),
+			status: MachineStatus::SystemMode
 		}
 	}
 
@@ -206,6 +224,15 @@ impl Machine {
 		s
 	}
 
+	pub fn raise_exception(&mut self, exception: ExceptionType, address : u64) -> Result<(), MachineError>{
+
+		self.set_status(MachineStatus::SystemMode);
+		// Handle the interruption
+		exception::call(exception, self); // todo: return error if the syscall code is invalid 
+		self.set_status(MachineStatus::UserMode);
+		Ok(())
+	}
+
 	/// Execute the instructions table of a machine putted in param
 	/// 
 	/// ### Parameters
@@ -298,7 +325,7 @@ impl Machine {
 			RISCV_FP =>	self.fp_instruction(inst),
 
 			// Treatment for: SYSTEM CALLS
-			RISCV_SYSTEM => Err(format!("{:x}: System opcode\npc: {:x}", inst.opcode, self.pc))?,
+			RISCV_SYSTEM => self.raise_exception(ExceptionType::SyscallException, self.pc),
 
 			// Default case
 			_ => Err(format!("{:x}: Unknown opcode\npc: {:x}", inst.opcode, self.pc))?
@@ -640,6 +667,14 @@ impl Machine {
 	pub fn write_fp_register(&mut self, index: usize, value: f32) {
 		self.fp_reg.set_reg(index as u8, value);
 	}
+
+	pub fn get_status(&self) -> MachineStatus {
+		todo!()
+	}
+
+	pub fn set_status(&mut self, new_status: MachineStatus) {
+		self.status = new_status;
+	}
 }
 
 #[cfg(test)]