diff --git a/src/core/cbindings.ml b/src/core/cbindings.ml
index 302c812..43e79af 100644
--- a/src/core/cbindings.ml
+++ b/src/core/cbindings.ml
@@ -2,4 +2,4 @@ let () =
   Callback.register "oboy_name" Version.name;
   Callback.register "oboy_version" Version.version;
   Callback.register "oboy_load" State.load_cartridge;
-  Callback.register "oboy_bg_map" Memory.background_map;
+  Callback.register "oboy_bg_map" (Memory.background_map !State.state.memory);
diff --git a/src/core/memory.ml b/src/core/memory.ml
index 605911d..54343d7 100644
--- a/src/core/memory.ml
+++ b/src/core/memory.ml
@@ -109,12 +109,13 @@ let update_timers mem cycles =
     end
   end
 
-let background_map () =
+let background_map mem n =
   let bg_map = Array2.create Bigarray.int8_unsigned Bigarray.c_layout 8 8 in
   Array2.fill bg_map 0;
   for j = 0 to (Array2.dim2 bg_map) - 1 do
     for i = 0 to (Array2.dim1 bg_map) - 1 do
-      bg_map.{i, j} <- (i + j * Array2.dim1 bg_map) mod 4
+      (* bg_map.{i, j} <- (i + j * Array2.dim1 bg_map) mod 4 *)
+      bg_map.{i, j} <- n
     done
   done;
   bg_map
diff --git a/src/core/state.ml b/src/core/state.ml
index af47c15..672a150 100644
--- a/src/core/state.ml
+++ b/src/core/state.ml
@@ -1,16 +1,22 @@
 (* State of the world, contains all the required information at any point *)
 type t = {
   mutable cartridge : Cartridge.t option;
+  mutable memory : Memory.t option
 }
 
 (* Global reference *)
 let state = ref {
-  cartridge = None
+  cartridge = None;
+  memory = None
 }
 
 let load_cartridge file =
   let cartridge = Cartridge.read_cartridge file in
-  !state.cartridge <- cartridge;
   match cartridge with
-  | Some c -> Cartridge.print_info c; true
+  | Some c -> begin
+    let memory = Memory.init c in
+    !state.cartridge <- cartridge;
+    !state.memory <- Some memory;
+    Cartridge.print_info c
+  end; true
   | None -> false
diff --git a/src/qt/oboy.cpp b/src/qt/oboy.cpp
index 062536f..a72ef90 100644
--- a/src/qt/oboy.cpp
+++ b/src/qt/oboy.cpp
@@ -88,9 +88,11 @@ bool OBoy::loaded() const
     return _loaded;
 }
 
-QImage OBoy::backgroundMap() const
+QImage OBoy::backgroundMap(int index) const
 {
     CAMLparam0();
+    CAMLlocal1(ocaml_index);
+    ocaml_index = index;
 
     static value * closure_f = fetch_caml_callback("oboy_bg_map");
     if (closure_f == nullptr) {
@@ -98,7 +100,7 @@ QImage OBoy::backgroundMap() const
         return QImage(0, 0, QImage::Format_Indexed8);
     }
 
-    const auto bg_array = Caml_ba_array_val(caml_callback(*closure_f, Val_unit));
+    const auto bg_array = Caml_ba_array_val(caml_callback(*closure_f, Val_int(ocaml_index)));
     const auto bg_raw_data = static_cast<caml_ba_uint8 *>(bg_array->data);
 
     Q_ASSERT(bg_array->num_dims == 2);
diff --git a/src/qt/oboy.h b/src/qt/oboy.h
index 8e678e1..9474248 100644
--- a/src/qt/oboy.h
+++ b/src/qt/oboy.h
@@ -10,7 +10,6 @@ class OBoy : public QObject
     Q_PROPERTY(QString name READ name CONSTANT)
     Q_PROPERTY(QString version READ version CONSTANT)
     Q_PROPERTY(bool loaded READ loaded NOTIFY loadedChanged)
-    Q_PROPERTY(QImage backgroundMap READ backgroundMap CONSTANT)
 public:
     explicit OBoy(QObject *parent = nullptr);
 
@@ -18,7 +17,7 @@ public:
     QString version() const;
     bool loaded() const;
     Q_INVOKABLE bool load(const QString &path);
-    QImage backgroundMap() const;
+    QImage backgroundMap(int index) const;
 
 signals:
     void loadedChanged(bool loaded);
diff --git a/src/qt/oimageprovider.cpp b/src/qt/oimageprovider.cpp
index 85e9833..88a6780 100644
--- a/src/qt/oimageprovider.cpp
+++ b/src/qt/oimageprovider.cpp
@@ -17,6 +17,6 @@ QImage OImageProvider::requestImage(const QString &id, QSize *size, const QSize
     }
     Q_ASSERT(oboy->loaded());
 
-    QImage img = oboy->backgroundMap();
+    QImage img = oboy->backgroundMap(0);
     return img;
 }