diff --git a/src/cpu.ml b/src/cpu.ml
index 3b20f23..102c11d 100644
--- a/src/cpu.ml
+++ b/src/cpu.ml
@@ -31,19 +31,21 @@ type t = {
 }
 
 let print_cpu_state cpu =
-  printf "Registers:\n";
-  printf "  A: 0x%02X  F: 0x%02X\n" (int_of_char cpu.reg.a) (int_of_char cpu.reg.f);
-  printf "  B: 0x%02X  C: 0x%02X\n" (int_of_char cpu.reg.b) (int_of_char cpu.reg.c);
-  printf "  D: 0x%02X  E: 0x%02X\n" (int_of_char cpu.reg.d) (int_of_char cpu.reg.e);
-  printf "  H: 0x%02X  L: 0x%02X\n" (int_of_char cpu.reg.h) (int_of_char cpu.reg.l);
-  printf "  PC: 0x%04X\n" cpu.reg.pc;
-  printf "  SP: 0x%04X\n" cpu.reg.sp;
+  printf "[Cpu state] Registers:\n";
+  printf "[Cpu state] \tA: 0x%02X  \tF: 0x%02X\n" (int_of_char cpu.reg.a) (int_of_char cpu.reg.f);
+  printf "[Cpu state] \tB: 0x%02X  \tC: 0x%02X\n" (int_of_char cpu.reg.b) (int_of_char cpu.reg.c);
+  printf "[Cpu state] \tD: 0x%02X  \tE: 0x%02X\n" (int_of_char cpu.reg.d) (int_of_char cpu.reg.e);
+  printf "[Cpu state] \tH: 0x%02X  \tL: 0x%02X\n" (int_of_char cpu.reg.h) (int_of_char cpu.reg.l);
+  printf "[Cpu state] \tPC: 0x%04X\n" cpu.reg.pc;
+  printf "[Cpu state] \tSP: 0x%04X\n" cpu.reg.sp;
 
-  printf "Flags:\n";
-  printf "  Z: %b\n" cpu.flag.z;
-  printf "  N: %b\n" cpu.flag.n;
-  printf "  H: %b\n" cpu.flag.h;
-  printf "  C: %b\n" cpu.flag.c
+  printf "[Cpu state] Flags:\n";
+  printf "[Cpu state] \t ZNHC\n";
+  let z = if cpu.flag.z then 1 else 0 in
+  let n = if cpu.flag.n then 1 else 0 in
+  let h = if cpu.flag.h then 1 else 0 in
+  let c = if cpu.flag.c then 1 else 0 in
+  printf "[Cpu state] \t[%d%d%d%d]\n" z n h c
 
 (** http://bgb.bircd.org/pandocs.htm#powerupsequence *)
 let init_registers =
@@ -136,152 +138,176 @@ let run cpu (mem: Memory.map) =
   print_cpu_state cpu;
   let opcode = read_pc_byte cpu mem |> char_of_int in
 (*  Hexa.print_slice cartridge.full_rom cpu.reg.pc (cpu.reg.pc + 7); *)
-  match opcode with
+
+  let inst = match opcode with
 
   (* 8-bit load *)
   (* LD   r,(HL) *)
-  | '\x7E' -> printf "  LD \tA, (HL)\n";
+  | '\x7E' -> let inst = sprintf "LD \tA, (HL)" in
               let hl = merge_bytes cpu.reg.l cpu.reg.h in
               cpu.reg.a <- Memory.get mem hl;
-              inc_cycles cpu 8
+              inc_cycles cpu 8;
+              inst
 
   | '\x36' -> let n = read_pc_byte cpu mem in
-              printf "  LD \t(HL) 0x%02X\n" n;
+              let inst = sprintf "LD \t(HL) 0x%02X" n in
               let hl = merge_bytes cpu.reg.l cpu.reg.h in
               Memory.set mem hl (char_of_int n);
-              inc_cycles cpu 12
+              inc_cycles cpu 12;
+              inst
 
 
   (* CPU control *)
-  | '\x00' -> printf "  NOP\n";
-              inc_cycles cpu 4
+  | '\x00' -> let inst = sprintf "NOP" in
+              inc_cycles cpu 4;
+              inst
 
 
   (* jump *)
-  | '\xC9' -> printf "  RET\n";
-              cpu.reg.pc <- pop_stack cpu mem;
-              inc_cycles cpu 16
+  | '\x20' -> let n = read_pc_byte cpu mem in
+              let inst = sprintf "JR \tNZ, 0x%02X" n in
+              if cpu.flag.z = false then
+              begin
+                inc_pc cpu (n - 1); inc_cycles cpu 12;
+              end else
+                inc_cycles cpu 8;
+              inst
 
-  | '\xC0' -> printf "  RET \tNZ\n";
+  | '\xC9' -> let inst = sprintf "RET" in
+              cpu.reg.pc <- pop_stack cpu mem;
+              inc_cycles cpu 16;
+              inst
+
+  | '\xC0' -> let inst = sprintf "RET \tNZ" in
               if cpu.flag.z = false then
               begin
                 cpu.reg.pc <- pop_stack cpu mem;
-                inc_cycles cpu 20
+                inc_cycles cpu 20;
               end else
-                inc_cycles cpu 8
+                inc_cycles cpu 8;
+              inst
 
 
 
-  | '\x03' -> printf "  INC \tBC\n";
+  | '\x03' -> let inst = sprintf "INC \tBC" in
               inc_BC cpu;
-              inc_cycles cpu 8
+              inc_cycles cpu 8;
+              inst
               
-  | '\x05' -> printf "  DEC \tB\n";
+  | '\x05' -> let inst = sprintf "DEC \tB" in
               let dec = int_of_char(cpu.reg.b) - 1 in
               cpu.flag.z <- dec = 0;
               cpu.flag.n <- true;
               cpu.flag.h <- dec < 0; 
               cpu.reg.b <- char_of_int @@ if dec >= 0 then dec else 0;
-              inc_cycles cpu 4
+              inc_cycles cpu 4;
+              inst
 
   | '\x06' -> let n = read_pc_byte cpu mem in
-              printf "  LD \tB, 0x%02X\n" n;
+              let inst = sprintf "LD \tB, 0x%02X" n in
               cpu.reg.b <- char_of_int n;
-              inc_cycles cpu 8
+              inc_cycles cpu 8;
+              inst
 
   | '\x18' -> let n = read_pc_byte cpu mem in
-              printf "  JP \t0x%02X\n" n;
-              inc_pc cpu (n - 1); inc_cycles cpu 12
-
-  | '\x20' -> let n = read_pc_byte cpu mem in
-              printf "  JR \tNZ, 0x%02X\n" n;
-              if cpu.flag.z = false then
-              begin
-                inc_pc cpu (n - 1); inc_cycles cpu 12
-              end else
-              begin
-                inc_cycles cpu 8
-              end
+              let inst = sprintf "JP \t0x%02X" n in
+              inc_pc cpu (n - 1); inc_cycles cpu 12;
+              inst
 
   | '\x21' -> let nn = read_pc_2bytes cpu mem in
-              printf "  LD \tHL, 0x%04X\n" nn;
+              let inst = sprintf "LD \tHL, 0x%04X" nn in
               let high, low = split_2B nn in
               cpu.reg.h <- high;
               cpu.reg.l <- low;
-              inc_cycles cpu 12
+              inc_cycles cpu 12;
+              inst
 
-  | '\x22' -> printf "  LDI \t(HL), A\n";
+  | '\x22' -> let inst = sprintf "LDI \t(HL), A" in
               let hl = merge_bytes cpu.reg.l cpu.reg.h in
               Memory.set mem hl cpu.reg.a;
               let high, low = split_2B (hl + 1) in
               cpu.reg.h <- high;
               cpu.reg.l <- low;
-              inc_cycles cpu 8
+              inc_cycles cpu 8;
+              inst
 
 
   | '\x28' -> let n = read_pc_byte cpu mem in
-              printf "  JR \tZ, 0x%02X\n" n;
+              let inst = sprintf "JR \tZ, 0x%02X" n in
               if cpu.flag.z = true then
               begin
-                inc_pc cpu (n - 1); inc_cycles cpu 12
+                inc_pc cpu (n - 1); inc_cycles cpu 12;
               end else
-              begin
-                inc_cycles cpu 8
-              end
+                inc_cycles cpu 8;
+              inst
 
-  | '\x34' -> printf "  INC \t(HL)\n";
+  | '\x34' -> let inst = sprintf "INC \t(HL)" in
               let hl = merge_bytes cpu.reg.l cpu.reg.h in
               let v = Memory.get mem hl |> int_of_char in
               cpu.flag.z <- v + 1 = 0;
               cpu.flag.n <- false;
               cpu.flag.h <- v = 0b00001111;
               Memory.set mem hl (char_of_int (v + 1));
-              inc_cycles cpu 12
+              inc_cycles cpu 12;
+              inst
 
 
   | '\x3E' -> let n = read_pc_byte cpu mem in
-              printf "  LD \tA, 0x%02X\n" n;
+              let inst = sprintf "LD \tA, 0x%02X" n in
               cpu.reg.a <- char_of_int n;
-              inc_cycles cpu 8
+              inc_cycles cpu 8;
+              inst
 
-  | '\xAF' -> printf "  XOR \tA, A\n";
+  | '\xAF' -> let inst = sprintf "XOR \tA, A" in
               let int_A = int_of_char cpu.reg.a in
               cpu.reg.a <- char_of_int @@ int_A lxor int_A;
-              inc_cycles cpu 4
+              inc_cycles cpu 4;
+              inst
 
   | '\xC3' -> let addr = read_pc_2bytes cpu mem in
-              printf "  JP \t0x%04X\n" addr;
-              cpu.reg.pc <- addr; inc_cycles cpu 16
+              let inst = sprintf "JP \t0x%04X" addr in
+              cpu.reg.pc <- addr; inc_cycles cpu 16;
+              inst
 
   | '\xE0' -> let n = read_pc_byte cpu mem in
-              printf "  LDH \t(0xFF%02X), A\n" n;
+              let inst = sprintf "LDH \t(0xFF%02X), A" n in
               Memory.set mem (0xFF00 + n) cpu.reg.a;
-              inc_cycles cpu 12
+              inc_cycles cpu 12;
+              inst
 
   | '\xEA' -> let addr = read_pc_2bytes cpu mem in
-              printf "  LD \t(0X%04X), A\n" addr;
+              let inst = sprintf "LD \t(0X%04X), A" addr in
               Memory.set mem addr cpu.reg.a;
-              inc_cycles cpu 16
+              inc_cycles cpu 16;
+              inst
 
 
   | '\xF0' -> let n = read_pc_byte cpu mem in
-              printf "  LDH \tA, (0xFF%02X)\n" n;
+              let inst = sprintf "LDH \tA, (0xFF%02X)" n in
               cpu.reg.a <- Memory.get mem (0xFF00 + n);
-              inc_cycles cpu 12
+              inc_cycles cpu 12;
+              inst
 
-  | '\xF3' -> printf "  DI\n";
+  | '\xF3' -> let inst = sprintf "DI" in
               (* fixme *)
-              inc_cycles cpu 4
+              inc_cycles cpu 4;
+              inst
 
   | '\xFE' -> let n = read_pc_byte cpu mem in
-              printf "  CP \t0x%02X\n" n;
+              let inst = sprintf "CP \t0x%02X" n in
               cmp_A cpu n;
-              inc_cycles cpu 8
+              inc_cycles cpu 8;
+              inst
 
-  | '\xFB' -> printf "  EI\n";
+  | '\xFB' -> let inst = sprintf "EI" in
               (* enable interrupts, IME=1 *)
-              inc_cycles cpu 4
+              inc_cycles cpu 4;
+              inst
 
   |  x -> eprintf "opcode 0x%02X\n" (int_of_char x);
           eprintf "#cycles: %d\n" cpu.cycles;
           failwith "Unimplemented opcode."
+
+  in
+
+  printf "[Instruction] %s\n" inst