diff --git a/simulator/CMakeLists.txt b/simulator/CMakeLists.txt
index df19dac7a..7fe0f72d1 100644
--- a/simulator/CMakeLists.txt
+++ b/simulator/CMakeLists.txt
@@ -62,6 +62,7 @@ set(TESTS_CPPS
     func_sim/traps/t/unit_test.cpp
     func_sim/driver/t/unit_test.cpp
     func_sim/t/unit_test.cpp
+    func_sim/ooo_window/t/unit_test.cpp
     modules/fetch/bpu/t/unit_test.cpp
     modules/core/t/unit_test.cpp
     export/gdb/t/unit_test.cpp
@@ -187,6 +188,7 @@ add_library(mipt-mips-src OBJECT
     func_sim/func_sim.cpp
     func_sim/driver/driver.cpp
     func_sim/traps/trap.cpp
+    func_sim/ooo_window/ooo_window.cpp
     mips/mips_instr.cpp
     mips/mips_register/mips_register.cpp
     mips/mips_driver.cpp
diff --git a/simulator/func_sim/func_sim.cpp b/simulator/func_sim/func_sim.cpp
index 214eadcc0..a462d7d54 100644
--- a/simulator/func_sim/func_sim.cpp
+++ b/simulator/func_sim/func_sim.cpp
@@ -5,15 +5,22 @@
 
 #include "driver/driver.h"
 #include "func_sim.h"
+
 #include <kernel/kernel.h>
+#include <infra/config/config.h>
 
 #include <iostream>
 #include <sstream>
 #include <stdexcept>
 
+namespace config {
+    static Value<uint32> ooo_window_size = { "ooo_window_size", 0, "size of OOO window (ROB)"};
+} // namespace config
+
 template <typename ISA>
 FuncSim<ISA>::FuncSim( Endian endian, bool log, std::string_view isa)
     : BasicFuncSim( isa)
+    , ooo_window( config::ooo_window_size)
     , imem( endian)
     , driver( ISA::create_driver( this))
 {
@@ -91,6 +98,7 @@ Trap FuncSim<ISA>::run( uint64 instrs_to_run)
         auto result_trap = driver_step( instr);
         if ( result_trap != Trap::NO_TRAP)
             return result_trap;
+        ooo_window.write_instruction( instr);
     }
     return Trap(Trap::BREAKPOINT);
 }
diff --git a/simulator/func_sim/func_sim.h b/simulator/func_sim/func_sim.h
index b6bbc7bd1..e3e32e921 100644
--- a/simulator/func_sim/func_sim.h
+++ b/simulator/func_sim/func_sim.h
@@ -14,6 +14,7 @@
 #include <infra/exception.h>
 #include <memory/memory.h>
 #include <simulator.h>
+#include <func_sim/ooo_window/ooo_window.h>
 
 #include <memory>
 #include <string>
@@ -35,6 +36,7 @@ class FuncSim : public BasicFuncSim
     using RegisterUInt = typename ISA::RegisterUInt;
 
     private:
+        OOOWindow<FuncInstr> ooo_window;
         RF<FuncInstr> rf;
         uint64 sequence_id = 0;
         std::shared_ptr<FuncMemory> mem;
diff --git a/simulator/func_sim/ooo_window/t/unit_test.cpp b/simulator/func_sim/ooo_window/t/unit_test.cpp
new file mode 100644
index 000000000..1b1300dc0
--- /dev/null
+++ b/simulator/func_sim/ooo_window/t/unit_test.cpp
@@ -0,0 +1,38 @@
+
+#include <catch.hpp>
+
+#include <func_sim/ooo_window/ooo_window.h>
+#include <risc_v/riscv_instr.h>
+
+TEST_CASE( "OOO_Window: zero size")
+{
+    OOOWindow<RISCVInstr<uint32>> w( 0);
+    RISCVInstr<uint32> nop(0x0001);
+    w.write_instruction( nop);
+    w.write_instruction( nop);
+    w.write_instruction( nop);
+
+    CHECK( w.get_avg_independent_instructions() == 0);
+}
+
+TEST_CASE( "OOO_Window: all independent")
+{
+    OOOWindow<RISCVInstr<uint32>> w( 5);
+    RISCVInstr<uint32> instr(0x48fd); // c_li $a7, 31
+
+    for ( int i = 0; i < 1000; i++)
+        w.write_instruction( instr);
+
+    CHECK( w.get_avg_independent_instructions() == 5.0);
+}
+
+TEST_CASE( "OOO_Window: all dependent")
+{
+    OOOWindow<RISCVInstr<uint32>> w( 10);
+    RISCVInstr<uint32> instr(0x8df1); // c_and $a1, $a2
+
+    for ( int i = 0; i < 1000; i++)
+        w.write_instruction( instr);
+
+    CHECK( w.get_avg_independent_instructions() == 1.0); // the last instr. in the window is always independent
+}
diff --git a/simulator/func_sim/operation.h b/simulator/func_sim/operation.h
index 520a8f740..900df3e6d 100644
--- a/simulator/func_sim/operation.h
+++ b/simulator/func_sim/operation.h
@@ -234,7 +234,7 @@ class BaseInstruction : public Datapath<T>
     using MyDatapath = Datapath<T>;
     using Register = R;
     using RegisterUInt = T;
-    R get_src_num( size_t index) const { return ( index == 0) ? src1 : src2; }
+    R get_src_num( size_t index) const;
     R get_dst_num()  const { return dst;  }
     R get_dst2_num() const { return dst2; }
 
@@ -251,6 +251,17 @@ class BaseInstruction : public Datapath<T>
     R dst2 = R::zero();
 };
 
+template<typename T, typename R>
+R BaseInstruction<T, R>::get_src_num( size_t index) const
+{
+    if ( index == 0)
+        return src1;
+    else if ( index == 1)
+        return src2;
+    else
+        return src3;
+}
+
 template<typename T, typename R>
 std::string BaseInstruction<T, R>::generate_disasm() const
 {