diff --git a/Labs/10. Interrupt subsystem/tb_irq.sv b/Labs/10. Interrupt subsystem/tb_irq.sv
index e3ef01c3..8c768026 100644
--- a/Labs/10. Interrupt subsystem/tb_irq.sv	
+++ b/Labs/10. Interrupt subsystem/tb_irq.sv	
@@ -9,7 +9,6 @@
 //
 //////////////////////////////////////////////////////////////////////////////////
 
-
 module tb_irq();
     logic     clk_i;
     logic     rst_i;
@@ -22,14 +21,17 @@ module tb_irq();
     logic [31:0] irq_cause_o;
     logic        irq_o;
 
+    string str;
+
 interrupt_controller dut(.*);
+int err_count;
 
 always #5 clk_i <= ~clk_i;
 
 initial begin
-  $display("\n\n===========================\n\nPress button 'Run All' (F3)\n\n===========================\n\n");
+  $display("\n\n===========================\n\nPress button 'Run All' (F3)\n\n===========================\n\n", $time);
   $stop();
-  clk_i <= 0;
+  clk_i       = '0;
   exception_i = '0;
   mret_i      = '0;
   irq_req_i   = '0;
@@ -47,6 +49,9 @@ initial begin
   t10();
   t11();
   t12();
+  t13();
+  t14();
+  $display("Simulation finished. Number of errors: %d", err_count);
   $finish;
 end
 
@@ -62,7 +67,8 @@ mie_i       = 0;
 endtask
 logic [1:0] k;
 
-task t1();  
+task t1();
+  $display("TEST 01. Granted request.");
   reset();
   @(posedge clk_i);
   mret_i      = 0;
@@ -70,342 +76,317 @@ task t1();
   irq_req_i   = 1;
   mie_i       = 1;
   #1
-  if (irq_o!=1) $display("Error: irq_o != 1");
-  if (irq_ret_o!=0) $display("Error: irq_ret_o != 0");
-  if (irq_cause_o!=32'h1000_0010) $display("Error: irq_o != 32'h1000_0010");
+  eror_info(1,0);
   @(posedge clk_i);
 endtask
 
 task t2();
+  $display("TEST 02. Forbidden request.");
   reset();
   @(posedge clk_i);
-  mret_i        = 0;
+  mret_i      = 0;
   exception_i = 0;
   irq_req_i   = 1;
   mie_i       = 0;
   #1
-  if (irq_o!=0) $display("Error: irq_o != 0");
-  if (irq_ret_o!=0) $display("Error: irq_ret_o != 0");
-  if (irq_cause_o!=32'h1000_0010) $display("Error: irq_o != 32'h1000_0010");
-@(posedge clk_i);
+  eror_info(0,0);
+  @(posedge clk_i);
 endtask
 
 task t3();
+  $display("TEST 03. Another request while handling previous.");
   reset();
   @(posedge clk_i);
-  mret_i        = 0;
+  mret_i      = 0;
   exception_i = 0;
   irq_req_i   = 1;
   mie_i       = 1;
   @(posedge clk_i);
-  mret_i        = 0;
+  mret_i      = 0;
   exception_i = 0;
   irq_req_i   = 0;
   mie_i       = 1;
   #1
-  if (irq_o!=0) $display("Error: irq_o != 0");
-  if (irq_ret_o!=0) $display("Error: irq_ret_o != 0");
-  if (irq_cause_o!=32'h1000_0010) $display("Error: irq_o != 32'h1000_0010");
+  eror_info(0,0);
   @(posedge clk_i);
-  mret_i        = 0;
+  mret_i      = 0;
   exception_i = 0;
   irq_req_i   = 1;
   mie_i       = 1;
   #1
-  if (irq_o!=0) $display("Error: irq_o != 0");
-  if (irq_ret_o!=0) $display("Error: irq_ret_o != 0");
-  if (irq_cause_o!=32'h1000_0010) $display("Error: irq_o != 32'h1000_0010");
-@(posedge clk_i);
+  eror_info(0,0);
+  @(posedge clk_i);
 endtask
 
 task t4();
+  $display("TEST 04. Request while unhandled exception.");
   reset();
   @(posedge clk_i);
-  mret_i        = 0;
+  mret_i      = 0;
   exception_i = 1;
   irq_req_i   = 0;
   mie_i       = 1;
   @(posedge clk_i);
-  mret_i        = 0;
+  mret_i      = 0;
   exception_i = 0;
-  irq_req_i   = 1;
+  irq_req_i   = 0;
   mie_i       = 1;
   #1
-  if (irq_o!=0) $display("Error: irq_o != 0");
-  if (irq_ret_o!=0) $display("Error: irq_ret_o != 0");
-  if (irq_cause_o!=32'h1000_0010) $display("Error: irq_o != 32'h1000_0010");
-@(posedge clk_i);
+  eror_info(0,0);
+  @(posedge clk_i);
+  mret_i      = 0;
+  exception_i = 1;
+  irq_req_i   = 0;
+  mie_i       = 1;
+  #1
+  eror_info(0,0);
+  @(posedge clk_i);
 endtask
 
 task t5();
+  $display("TEST 05. MRET while handling interrupt only.");
   reset();
-@(posedge clk_i);
-  mret_i        = 0;
+  @(posedge clk_i);
+  mret_i      = 0;
   exception_i = 0;
   irq_req_i   = 1;
   mie_i       = 1;
-@(posedge clk_i);
-  mret_i        = 1;
+  @(posedge clk_i);
+  mret_i      = 1;
   exception_i = 0;
   irq_req_i   = 0;
   mie_i       = 1;
   #1
-  if (irq_o!=0) $display("Error: irq_o != 0");
-  if (irq_ret_o!=1) $display("Error: irq_ret_o != 1");
-  if (irq_cause_o!=32'h1000_0010) $display("Error: irq_o != 32'h1000_0010");
-@(posedge clk_i);
+  eror_info(0,1);
+  @(posedge clk_i);
 endtask
 
 task t6();
+  $display("TEST 06. MRET while handling exception only.");
   reset();
-@(posedge clk_i);
-  mret_i        = 0;
+  @(posedge clk_i);
+  mret_i      = 0;
   exception_i = 1;
   irq_req_i   = 0;
   mie_i       = 1;
-@(posedge clk_i);
-  mret_i        = 1;
+  @(posedge clk_i);
+  mret_i      = 1;
   exception_i = 0;
   irq_req_i   = 0;
   mie_i       = 1;
-  #1
-  if (irq_o!=0) $display("Error: irq_o != 0");
-  if (irq_ret_o!=0) $display("Error: irq_ret_o != 0");
-  if (irq_cause_o!=32'h1000_0010) $display("Error: irq_o != 32'h1000_0010");
-@(posedge clk_i);
+  eror_info(0,0);
+  @(posedge clk_i);
 endtask
 
 task t7();
+  $display("TEST 07. MRET while handling interrupt and exception.");
   reset();
-@(posedge clk_i);
-  mret_i        = 0;
+  @(posedge clk_i);
+  mret_i      = 0;
   exception_i = 0;
   irq_req_i   = 1;
   mie_i       = 1;
-@(posedge clk_i);
-  mret_i        = 0;
+  @(posedge clk_i);
+  mret_i      = 0;
   exception_i = 1;
-  irq_req_i   = 1;
-  mie_i       = 1;
-  #1
-  if (irq_o!=0) $display("Error: irq_o != 0");
-  if (irq_ret_o!=0) $display("Error: irq_ret_o != 0");
-@(posedge clk_i);
-  mret_i        = 1;
-  exception_i = 0;
   irq_req_i   = 0;
   mie_i       = 1;
   #1
-  if (irq_o!=0) $display("Error: irq_o != 0");
-  if (irq_ret_o!=0) $display("Error: irq_ret_o != 0");
-  if (irq_cause_o!=32'h1000_0010) $display("Error: irq_o != 32'h1000_0010");
-@(posedge clk_i);
-  mret_i        = 0;
+  eror_info(0,0);
+  @(posedge clk_i)
+  mret_i      = 1;
   exception_i = 0;
   irq_req_i   = 0;
   mie_i       = 1;
-  #1
-  if (irq_o!=0) $display("Error: irq_o != 0");
-  if (irq_ret_o!=0) $display("Error: irq_ret_o != 0");
-  if (irq_cause_o!=32'h1000_0010) $display("Error: irq_o != 32'h1000_0010");
+  eror_info(0,0);
   @(posedge clk_i);
 endtask
 
 task t8();
+  $display("TEST 08. Two MRETs while handling interrupt and exception.");
   reset();
-@(posedge clk_i);
-  mret_i        = 0;
+  @(posedge clk_i);
+  mret_i      = 0;
   exception_i = 0;
   irq_req_i   = 1;
   mie_i       = 1;
-@(posedge clk_i);
-  mret_i        = 0;
+  @(posedge clk_i);
+  mret_i      = 0;
   exception_i = 1;
-  irq_req_i   = 1;
+  irq_req_i   = 0;
   mie_i       = 1;
-  #1
-  if (irq_o!=0) $display("Error: irq_o != 0");
-  if (irq_ret_o!=0) $display("Error: irq_ret_o != 0");
-@(posedge clk_i);
-  mret_i        = 1;
+  @(posedge clk_i);
+  mret_i      = 1;
   exception_i = 0;
   irq_req_i   = 0;
   mie_i       = 1;
-  #1
-  if (irq_o!=0) $display("Error: irq_o != 0");
-  if (irq_ret_o!=0) $display("Error: irq_ret_o != 0");
-  if (irq_cause_o!=32'h1000_0010) $display("Error: irq_o != 32'h1000_0010");
-@(posedge clk_i);
-  mret_i        = 0;
+  @(posedge clk_i);
+  mret_i      = 0;
   exception_i = 0;
   irq_req_i   = 0;
   mie_i       = 1;
   #1
-  if (irq_o!=0) $display("Error: irq_o != 0");
-  if (irq_ret_o!=0) $display("Error: irq_ret_o != 0");
-  if (irq_cause_o!=32'h1000_0010) $display("Error: irq_o != 32'h1000_0010");
-  @(posedge clk_i);
-  mret_i        = 1;
+   @(posedge clk_i);
+  mret_i      = 1;
   exception_i = 0;
   irq_req_i   = 0;
   mie_i       = 1;
   #1
-  if (irq_o!=0) $display("Error: irq_o != 0");
-  if (irq_ret_o!=1) $display("Error: irq_ret_o != 1");
-  if (irq_cause_o!=32'h1000_0010) $display("Error: irq_o != 32'h1000_0010");
+  eror_info(0,1);
   @(posedge clk_i);
-
 endtask
 
 task t9();
+  $display("TEST 09. MRET while unhandled interrupt and subsequent request.");
   reset();
-@(posedge clk_i);
-  mret_i        = 0;
+  @(posedge clk_i);
+  mret_i      = 0;
   exception_i = 0;
   irq_req_i   = 1;
   mie_i       = 1;
-@(posedge clk_i);
-  mret_i        = 1;
+  @(posedge clk_i);
+  mret_i      = 1;
   exception_i = 0;
   irq_req_i   = 0;
   mie_i       = 1;
-  #1
-  if (irq_o!=0) $display("Error: irq_o != 0");
-  if (irq_ret_o!=1) $display("Error: irq_ret_o != 1");
-  if (irq_cause_o!=32'h1000_0010) $display("Error: irq_o != 32'h1000_0010");
-@(posedge clk_i);
-  mret_i        = 0;
+  @(posedge clk_i);
+  mret_i      = 0;
   exception_i = 0;
   irq_req_i   = 1;
   mie_i       = 1;
   #1
-  if (irq_o!=1) $display("Error: irq_o != 1");
-  if (irq_ret_o!=0) $display("Error: irq_ret_o != 0");
-  if (irq_cause_o!=32'h1000_0010) $display("Error: irq_o != 32'h1000_0010");
+  eror_info(1,0);
+  @(posedge clk_i);
 endtask
 
 task t10();
+  $display("TEST 10. MRET while unhandled exception and subsequent request.");
   reset();
-@(posedge clk_i);
-  mret_i        = 0;
+  @(posedge clk_i);
+  mret_i      = 0;
   exception_i = 1;
   irq_req_i   = 0;
   mie_i       = 1;
-@(posedge clk_i);
-  mret_i        = 1;
+  @(posedge clk_i);
+  mret_i      = 1;
   exception_i = 0;
   irq_req_i   = 0;
   mie_i       = 1;
-  #1
-  if (irq_o!=0) $display("Error: irq_o != 0");
-  if (irq_ret_o!=0) $display("Error: irq_ret_o != 0");
-  if (irq_cause_o!=32'h1000_0010) $display("Error: irq_o != 32'h1000_0010");
-@(posedge clk_i);
-  mret_i        = 0;
+  @(posedge clk_i);
+  mret_i      = 0;
   exception_i = 0;
   irq_req_i   = 1;
   mie_i       = 1;
   #1
-  if (irq_o!=1) $display("Error: irq_o != 1");
-  if (irq_ret_o!=0) $display("Error: irq_ret_o != 0");
-  if (irq_cause_o!=32'h1000_0010) $display("Error: irq_o != 32'h1000_0010");
+  eror_info(1,0);
+  @(posedge clk_i);
 endtask
 
 task t11();
+  $display("TEST 11. MRET while unhandled interrupt and exception and subsequent request.");
   reset();
-@(posedge clk_i);
-  mret_i        = 0;
-  exception_i = 0;
-  irq_req_i   = 1;
-  mie_i       = 1;
-@(posedge clk_i);
-  mret_i        = 0;
-  exception_i = 1;
-  irq_req_i   = 1;
-  mie_i       = 1;
-  #1
-  if (irq_o!=0) $display("Error: irq_o != 0");
-  if (irq_ret_o!=0) $display("Error: irq_ret_o != 0");
-@(posedge clk_i);
-  mret_i        = 1;
-  exception_i = 0;
-  irq_req_i   = 0;
-  mie_i       = 1;
-  #1
-  if (irq_o!=0) $display("Error: irq_o != 0");
-  if (irq_ret_o!=0) $display("Error: irq_ret_o != 0");
-  if (irq_cause_o!=32'h1000_0010) $display("Error: irq_o != 32'h1000_0010");
-@(posedge clk_i);
-  mret_i        = 0;
-  exception_i = 0;
-  irq_req_i   = 0;
-  mie_i       = 1;
-  #1
-  if (irq_o!=0) $display("Error: irq_o != 0");
-  if (irq_ret_o!=0) $display("Error: irq_ret_o != 0");
-  if (irq_cause_o!=32'h1000_0010) $display("Error: irq_o != 32'h1000_0010");
   @(posedge clk_i);
-  mret_i        = 0;
+  mret_i      <= 0;
+  exception_i <= 0;
+  irq_req_i   <= 1;
+  mie_i       <= 1;
+  @(posedge clk_i);
+  mret_i      <= 0;
+  exception_i <= 1;
+  irq_req_i   <= 0;
+  mie_i       <= 1;
+  @(posedge clk_i);
+  mret_i      <= 1;
+  exception_i <= 0;
+  irq_req_i   <= 0;
+  mie_i       <= 1;
+  @(posedge clk_i);
+  mret_i      = 0;
   exception_i = 0;
   irq_req_i   = 1;
   mie_i       = 1;
   #1
-  if (irq_o!=0) $display("Error: irq_o != 0");
-  if (irq_ret_o!=0) $display("Error: irq_ret_o != 0");
-  if (irq_cause_o!=32'h1000_0010) $display("Error: irq_o != 32'h1000_0010");
+  eror_info(0,0);
+  @(posedge clk_i);
+
 endtask
 
 task t12();
- reset();
-@(posedge clk_i);
-  mret_i        = 0;
+  $display("TEST 12. Two MRETs while unhandled interrupt and exception and susbsequent request.");
+  reset();
+  @(posedge clk_i);
+  mret_i      = 0;
   exception_i = 0;
   irq_req_i   = 1;
   mie_i       = 1;
-@(posedge clk_i);
-  mret_i        = 0;
+  @(posedge clk_i);
+  mret_i      = 0;
   exception_i = 1;
-  irq_req_i   = 1;
+  irq_req_i   = 0;
   mie_i       = 1;
-  #1
-  if (irq_o!=0) $display("Error: irq_o != 0");
-  if (irq_ret_o!=0) $display("Error: irq_ret_o != 0");
-@(posedge clk_i);
-  mret_i        = 1;
+  @(posedge clk_i);
+  mret_i      = 1;
   exception_i = 0;
   irq_req_i   = 0;
   mie_i       = 1;
-  #1
-  if (irq_o!=0) $display("Error: irq_o != 0");
-  if (irq_ret_o!=0) $display("Error: irq_ret_o != 0");
-  if (irq_cause_o!=32'h1000_0010) $display("Error: irq_o != 32'h1000_0010");
-@(posedge clk_i);
-  mret_i        = 0;
+  @(posedge clk_i);
+  mret_i      = 0;
   exception_i = 0;
   irq_req_i   = 0;
   mie_i       = 1;
-  #1
-  if (irq_o!=0) $display("Error: irq_o != 0");
-  if (irq_ret_o!=0) $display("Error: irq_ret_o != 0");
-  if (irq_cause_o!=32'h1000_0010) $display("Error: irq_o != 32'h1000_0010");
   @(posedge clk_i);
-  mret_i        = 1;
+  mret_i      = 1;
   exception_i = 0;
   irq_req_i   = 0;
   mie_i       = 1;
+  @(posedge clk_i);
+  mret_i      = 0;
+  exception_i = 0;
+  irq_req_i   = 1;
+  mie_i       = 1;
   #1
-  if (irq_o!=0) $display("Error: irq_o != 0");
-  if (irq_ret_o!=1) $display("Error: irq_ret_o != 1");
-  if (irq_cause_o!=32'h1000_0010) $display("Error: irq_o != 32'h1000_0010");
-@(posedge clk_i);
-  mret_i        = 0;
+  str = "request interrupt after 2 mret for interrupt and exception";
+  eror_info(1,0);
+  @(posedge clk_i);
+endtask
+
+task t13();
+  $display("TEST 13. Request next cycle after excetion.");
+  reset();
+  @(posedge clk_i);
+  mret_i      = 0;
+  exception_i = 1;
+  irq_req_i   = 0;
+  mie_i       = 1;
+  @(posedge clk_i);
+  mret_i      = 0;
   exception_i = 0;
   irq_req_i   = 1;
   mie_i       = 1;
   #1
-  if (irq_o!=1) $display("Error: irq_o != 1");
-  if (irq_ret_o!=0) $display("Error: irq_ret_o != 0");
-  if (irq_cause_o!=32'h1000_0010) $display("Error: irq_o != 32'h1000_0010");
+  eror_info(0,0);
+  @(posedge clk_i);
+endtask
+
+task t14();
+  $display("TEST 14. Request same cycle with the exception.");
+  reset();
+  @(posedge clk_i);
+  mret_i      = 0;
+  exception_i = 1;
+  irq_req_i   = 1;
+  mie_i       = 1;
+  #1
+  eror_info(0,0);
+  @(posedge clk_i);
+endtask
+
+//logic irq, irq_ret;
+
+task eror_info(irq, irq_ret);
+  if (irq_o!=irq)                 begin $error("invalid irq_o       = %b, expected value %b."           , irq_o, irq        ); err_count++; end
+  if (irq_ret_o!=irq_ret)         begin $error("invalid irq_ret_o   = %b, expected value %b."           , irq_ret_o, irq_ret); err_count++; end
+  if (irq_cause_o!=32'h1000_0010) begin $error("invalid irq_cause_o = %h, expected value 32'h1000_0010.", irq_cause_o       ); err_count++; end
 endtask
 
 endmodule