diff --git a/rtl/alu.v b/rtl/alu.v
index 5ecee99..9607a2c 100644
--- a/rtl/alu.v
+++ b/rtl/alu.v
@@ -1,6 +1,19 @@
-module alu (S, A, B);
-    output [31:0] S;
-    input [31:0] A, B;
+module alu (input [31:0] input_a, input_b,
+            input [2:0] op_code,
+            output reg [31:0] out);
+    
+    always@ (*) begin
+        case (op_code)
+            3'b000 : out <= input_a + input_b;
+            3'b001 : out <= input_a << input_b;
+            3'b010 : out <= (input_a < input_b) ? 1 : 0;
+            3'b011 : out <= input_a ^ input_b;
+            3'b100 : out <= input_a >> input_b;
+            3'b101 : out <= input_a >>> input_b;
+            3'b110 : out <= input_a | input_b;
+            3'b111 : out <= input_a & input_b;
+            default : out <= 32'b0;
+        endcase
+    end
 
-    xor N[31:0] (S, A, B);
-endmodule
\ No newline at end of file
+endmodule
diff --git a/rtl/decoder.v b/rtl/decoder.v
new file mode 100644
index 0000000..ffc8254
--- /dev/null
+++ b/rtl/decoder.v
@@ -0,0 +1,19 @@
+module decoder (input [31:0] instruction,
+                output immediate,
+                output we_reg, adder_pc,
+                output [1:0] input_reg,
+                output [4:0] select_a, select_b, select_d,
+                output source_alu,
+                output [2:0] op_code_alu,
+                output mem_we,
+                output [31:0] mem_address
+                output jmp_pc, b_pc);
+
+    always @(*) begin
+        if (reset == 1)
+            registers[0] <= 32'b0;
+        else if (we == 1)
+            registers[select_d] <= input_d;
+    end
+
+endmodule
diff --git a/rtl/instruction.v b/rtl/instruction.v
new file mode 100644
index 0000000..a91d9fb
--- /dev/null
+++ b/rtl/instruction.v
@@ -0,0 +1,8 @@
+module instruction (input [31:0] address,
+                       output [31:0] instruction);
+    
+    reg [63:0] memory [31:0];
+
+    assign instruction = memory[address];
+
+endmodule
diff --git a/rtl/memory.v b/rtl/memory.v
new file mode 100644
index 0000000..a19b913
--- /dev/null
+++ b/rtl/memory.v
@@ -0,0 +1,18 @@
+module instruction (input clock, reset,
+                    input we,
+                    input [31:0] address,
+                    input [31:0] data_in
+                    output [31:0] data_out);
+    
+    reg [63:0] memory [31:0];
+
+    always @(posedge clock, reset) begin
+        if (reset == 1)
+            memory[0] <= 32'b0;
+        else if (we == 1)
+            memory[address] <= data_in;
+    end
+
+    assign data_out = memory[address];
+
+endmodule
diff --git a/rtl/mux2_1.v b/rtl/mux2_1.v
new file mode 100644
index 0000000..3711974
--- /dev/null
+++ b/rtl/mux2_1.v
@@ -0,0 +1,7 @@
+module mux2_1 (input [31:0] A, B,
+               input S,
+               output [31:0] O);
+    
+    assign O = S ? B : A;
+
+endmodule
\ No newline at end of file
diff --git a/rtl/mux4_1.v b/rtl/mux4_1.v
new file mode 100644
index 0000000..80c50ab
--- /dev/null
+++ b/rtl/mux4_1.v
@@ -0,0 +1,8 @@
+module mux4_1 (input [31:0] A, B, C, D,
+               input [1:0] S,
+               output [31:0] O);
+    
+    assign O = S[0] ? (S[1] ? D : C)
+                    : (S[1] ? B : A);
+
+endmodule
diff --git a/rtl/program_counter.v b/rtl/program_counter.v
new file mode 100644
index 0000000..c9dfc65
--- /dev/null
+++ b/rtl/program_counter.v
@@ -0,0 +1,12 @@
+module program_counter (input clock, reset,
+           input [31:0] new_pc,
+           output reg [31:0] pc);
+    
+    always @ (posedge clock, reset) begin
+        if (reset == 1)
+            pc <= 32'b0;
+        else
+            pc <= new_pc;
+    end
+
+endmodule
diff --git a/rtl/registers_bank.v b/rtl/registers_bank.v
new file mode 100644
index 0000000..3af16b2
--- /dev/null
+++ b/rtl/registers_bank.v
@@ -0,0 +1,18 @@
+module registers_bank (input clock, reset, we,
+                       input [4:0] select_d, select_a, select_b,
+                       input [31:0] input_d,
+                       output [31:0] output_a, output_b);
+    
+    reg [31:0] registers[31:0];
+    
+    always @(posedge clock, reset) begin
+        if (reset == 1)
+            registers[0] <= 32'b0;
+        else if (we == 1)
+            registers[select_d] <= input_d;
+    end
+
+    assign output_a = registers[select_a];
+    assign output_b = registers[select_b];
+
+endmodule
diff --git a/scripts/gen_simu_do.sh b/scripts/gen_simu_do.sh
index 09aecb4..60f3f94 100755
--- a/scripts/gen_simu_do.sh
+++ b/scripts/gen_simu_do.sh
@@ -33,5 +33,3 @@ add wave -radix unsigned *' >> ./sim/simu.do
 echo 'run -all' >> ./sim/simu.do
 
 exit 0
-
-# CRC - Hamming Code
diff --git a/tb/tb_alu.v b/tb/tb_alu.v
index c07f90a..c9f80d9 100644
--- a/tb/tb_alu.v
+++ b/tb/tb_alu.v
@@ -1,3 +1,41 @@
-module tb_alu (S);
-    output [31:0] S;
-endmodule
\ No newline at end of file
+`timescale 1ns / 1ps
+
+module tb_alu ();
+// Design Inputs and outputs
+reg [31:0] in_a;
+reg [31:0] in_b;
+reg [2:0] op_code;
+wire [31:0] out;
+
+// DUT instantiation
+alu alu (
+    .input_a(in_a),
+    .input_b(in_b),
+    .op_code(op_code),
+    .out(out)
+);
+
+// Test stimulus
+initial begin
+    // Use the monitor task to display the FPGA IO
+    $monitor("time=%3d, in_a=%d, in_b=%d, ctrl=%b, q=%d \n",
+                $time, in_a, in_b, op_code, out);
+
+    // Generate each input with a 20 ns delay between them
+    in_a = 1'b0;
+    in_b = 1'b0;
+    op_code = 3'b000;
+    #20
+    if (out !== 0) $display("[FAILED] output should be 0");
+    in_a = 1'b1;
+    #20
+    if (out !== 1) $display("[FAILED] output should be 1");
+    in_b = 1'b1;
+    #20
+    if (out !== 2) $display("[FAILED] output should be 2");
+    op_code = 3'b001;
+    #20
+    if (out !== 2) $display("[FAILED] output should be 2");
+end
+
+endmodule : tb_alu
diff --git a/tb/tb_mux2_1.v b/tb/tb_mux2_1.v
new file mode 100644
index 0000000..b36081f
--- /dev/null
+++ b/tb/tb_mux2_1.v
@@ -0,0 +1,61 @@
+`timescale 1ns / 1ps
+
+module tb_mux2_1 ();
+// Clock and reset signals
+reg clk;
+reg reset;
+
+// Design Inputs and outputs
+reg [31:0] in_a;
+reg [31:0] in_b;
+reg ctrl;
+wire [31:0] out;
+
+// DUT instantiation
+mux2_1 mux (
+    .S(ctrl),
+    .A(in_a),
+    .B(in_b),
+    .O(out)
+);
+
+// generate the clock
+initial begin
+    clk = 1'b0;
+    // forever #1 clk = ~clk;
+end
+
+// Generate the reset
+initial begin
+    reset = 1'b1;
+    #10
+    reset = 1'b0;
+end
+
+// Test stimulus
+initial begin
+    // Use the monitor task to display the FPGA IO
+    $monitor("time=%3d, in_a=%d, in_b=%d, ctrl=%b, q=%d \n",
+                $time, in_a, in_b, ctrl, out);
+
+    // Generate each input with a 20 ns delay between them
+    in_a = 1'b0;
+    in_b = 1'b0;
+    ctrl = 1'b0;
+    #20
+    if (out !== 0) $display("[FAILED] output should be 0");
+    in_a = 1'b1;
+    #20
+    if (out !== 1) $display("[FAILED] output should be 1");
+    ctrl = 1'b1;
+    in_a = 1'b0;
+    in_b = 1'b1;
+    #20
+    if (out !== 1) $display("[FAILED] output should be 1");
+    ctrl = 1'b0;
+    in_a = 1'b1;
+    #20
+    if (out !== 1) $display("[FAILED] output should be 1");
+end
+
+endmodule : tb_mux2_1