diff --git a/lib/cartridge/detect_cartridge.ml b/lib/cartridge/detect_cartridge.ml
index e61bbb5..83b53f8 100644
--- a/lib/cartridge/detect_cartridge.ml
+++ b/lib/cartridge/detect_cartridge.ml
@@ -8,4 +8,7 @@ let f ~rom_bytes =
   | MBC1
   | MBC1_RAM
   | MBC1_RAM_BATTERY        -> (module Mbc1 : Cartridge_intf.S)
-  | _                       -> assert false
+  | MBC2
+  | MBC2_BATTERY            -> (module Mbc2 : Cartridge_intf.S)
+  | other ->
+    failwith (Printf.sprintf "Unsupported cartridge type: %s" (Cartridge_type.show other))
diff --git a/lib/cartridge/mbc2.ml b/lib/cartridge/mbc2.ml
new file mode 100644
index 0000000..f8d61fe
--- /dev/null
+++ b/lib/cartridge/mbc2.ml
@@ -0,0 +1,84 @@
+(* MBC2 - Memory Bank Controller 2
+
+   Features:
+   - Up to 256KB ROM (16 banks)
+   - Built-in 512×4 bits RAM (only lower nibble used)
+   - RAM at 0xA000-0xA1FF (mirrored in 0xA200-0xBFFF)
+
+   Register writes:
+   - 0x0000-0x3FFF with bit 8 = 0: RAM enable (0x0A enables)
+   - 0x0000-0x3FFF with bit 8 = 1: ROM bank number (4 bits, 0→1)
+
+   Reference: https://gbdev.io/pandocs/MBC2.html *)
+
+open Uints
+
+type t = {
+  rom_bytes : Bigstringaf.t;
+  ram_bytes : Bigstringaf.t;
+  rom_bank_count : int;
+  mutable ram_enabled : bool;
+  mutable rom_bank_num : int;
+}
+
+let create ~rom_bytes =
+  let h = Cartridge_header.create ~rom_bytes in
+  let rom_bank_count = Cartridge_header.get_rom_bank_count h in
+  (* MBC2 has built-in 512×4 bit RAM *)
+  let ram_bytes = Bigstringaf.create 512 in
+  {
+    rom_bytes;
+    ram_bytes;
+    rom_bank_count;
+    ram_enabled = false;
+    rom_bank_num = 1;
+  }
+
+let read_byte t addr =
+  let addr = Uint16.to_int addr in
+  match addr with
+  | _ when addr <= 0x3FFF ->
+    Bigstringaf.unsafe_get t.rom_bytes addr
+    |> Uint8.of_char
+  | _ when addr <= 0x7FFF ->
+    let offset = 0x4000 * t.rom_bank_num + (addr - 0x4000) in
+    Bigstringaf.unsafe_get t.rom_bytes offset
+    |> Uint8.of_char
+  | _ when 0xA000 <= addr && addr <= 0xBFFF ->
+    (* RAM - 512 bytes mirrored, only lower 4 bits valid
+       This memory is at A000–A1FF and mirrored at
+       A200–BFFF hence the 0x1FF below. *)
+    if t.ram_enabled then
+      let ram_addr = (addr - 0xA000) land 0x1FF in
+      let value = Bigstringaf.unsafe_get t.ram_bytes ram_addr |> Char.code in
+      Uint8.of_int (value lor 0xF0)  (* Upper 4 bits read as 1 *)
+    else
+      Uint8.of_int 0xFF
+  | _ -> assert false
+
+let write_byte t ~addr ~data =
+  let addr = Uint16.to_int addr in
+  let data = Uint8.to_int data in
+  match addr with
+  | _ when addr <= 0x3FFF ->
+    if addr land 0x100 = 0 then
+      t.ram_enabled <- (data land 0x0F) = 0x0A
+    else begin
+      let bank = data land 0x0F in
+      let bank = if bank = 0 then 1 else bank in
+      t.rom_bank_num <- bank mod t.rom_bank_count
+    end
+  | _ when 0x4000 <= addr && addr <= 0x7FFF ->
+    (* Writes to this area do nothing on MBC2 *)
+    ()
+  | _ when 0xA000 <= addr && addr <= 0xBFFF ->
+    (* RAM - only lower 4 bits written *)
+    if t.ram_enabled then begin
+      let ram_addr = (addr - 0xA000) land 0x1FF in
+      Bigstringaf.unsafe_set t.ram_bytes ram_addr (Char.unsafe_chr (data land 0x0F))
+    end
+  | _ -> assert false
+
+let accepts _ addr =
+  let addr = Uint16.to_int addr in
+  (addr <= 0x7FFF) || (0xA000 <= addr && addr <= 0xBFFF)
diff --git a/lib/cartridge/mbc2.mli b/lib/cartridge/mbc2.mli
new file mode 100644
index 0000000..c3c85ec
--- /dev/null
+++ b/lib/cartridge/mbc2.mli
@@ -0,0 +1 @@
+include Cartridge_intf.S
diff --git a/resource/test_roms/mooneye/mbc2/bits_ramg.gb b/resource/test_roms/mooneye/mbc2/bits_ramg.gb
new file mode 100644
index 0000000..887786c
Binary files /dev/null and b/resource/test_roms/mooneye/mbc2/bits_ramg.gb differ
diff --git a/resource/test_roms/mooneye/mbc2/bits_romb.gb b/resource/test_roms/mooneye/mbc2/bits_romb.gb
new file mode 100644
index 0000000..bb7ab4c
Binary files /dev/null and b/resource/test_roms/mooneye/mbc2/bits_romb.gb differ
diff --git a/resource/test_roms/mooneye/mbc2/bits_unused.gb b/resource/test_roms/mooneye/mbc2/bits_unused.gb
new file mode 100644
index 0000000..f25dc01
Binary files /dev/null and b/resource/test_roms/mooneye/mbc2/bits_unused.gb differ
diff --git a/resource/test_roms/mooneye/mbc2/ram.gb b/resource/test_roms/mooneye/mbc2/ram.gb
new file mode 100644
index 0000000..e570e1c
Binary files /dev/null and b/resource/test_roms/mooneye/mbc2/ram.gb differ
diff --git a/resource/test_roms/mooneye/mbc2/rom_1Mb.gb b/resource/test_roms/mooneye/mbc2/rom_1Mb.gb
new file mode 100644
index 0000000..1d45bf8
Binary files /dev/null and b/resource/test_roms/mooneye/mbc2/rom_1Mb.gb differ
diff --git a/resource/test_roms/mooneye/mbc2/rom_2Mb.gb b/resource/test_roms/mooneye/mbc2/rom_2Mb.gb
new file mode 100644
index 0000000..d5b4e0d
Binary files /dev/null and b/resource/test_roms/mooneye/mbc2/rom_2Mb.gb differ
diff --git a/resource/test_roms/mooneye/mbc2/rom_512kb.gb b/resource/test_roms/mooneye/mbc2/rom_512kb.gb
new file mode 100644
index 0000000..b8997c7
Binary files /dev/null and b/resource/test_roms/mooneye/mbc2/rom_512kb.gb differ
diff --git a/test/rom_test/mooneye/mooneye_utils.ml b/test/rom_test/mooneye/mooneye_utils.ml
index d5b6bd5..d7d1257 100644
--- a/test/rom_test/mooneye/mooneye_utils.ml
+++ b/test/rom_test/mooneye/mooneye_utils.ml
@@ -12,28 +12,25 @@ module Make (Cartridge : Cartridge_intf.S) = struct
       let run_result = Camlboy.run_instruction camlboy in
       let prev_instr = Camlboy.For_tests.prev_inst camlboy in
       match prev_instr, run_result with
-      | JR (None, i8), Frame_ended famebuffer ->
-        if Int8.to_int i8 <> -3 then
-          loop ()
-        else begin
-          Printf.printf "%s\n" @@ Camlboy.show camlboy;
-          famebuffer
-          |> Array.iteri (fun i row ->
-              if row |> Array.for_all (fun color -> color = `White) then
-                ()
-              else begin
-                let show_color = function
-                  | `Black -> '#'
-                  | `Dark_gray -> '@'
-                  | `Light_gray -> 'x'
-                  | `White -> '-'
-                in
-                Printf.printf "%03d:" i;
-                row |> Array.iter (fun color -> show_color color |> print_char);
-                print_newline ()
-              end
-            )
-        end
+      | JR (None, i8), Frame_ended famebuffer
+          when List.mem (Int8.to_int i8) [-2; -3] ->
+        Printf.printf "%s\n" @@ Camlboy.show camlboy;
+        famebuffer
+        |> Array.iteri (fun i row ->
+            if row |> Array.for_all (fun color -> color = `White) then
+              ()
+            else begin
+              let show_color = function
+                | `Black -> '#'
+                | `Dark_gray -> '@'
+                | `Light_gray -> 'x'
+                | `White -> '-'
+              in
+              Printf.printf "%03d:" i;
+              row |> Array.iter (fun color -> show_color color |> print_char);
+              print_newline ()
+            end
+          )
       | _, _ -> loop ()
     in
     loop ()
diff --git a/test/rom_test/mooneye/test_mooneye_mbc2.ml b/test/rom_test/mooneye/test_mooneye_mbc2.ml
new file mode 100644
index 0000000..6810268
--- /dev/null
+++ b/test/rom_test/mooneye/test_mooneye_mbc2.ml
@@ -0,0 +1,86 @@
+open Camlboy_lib
+module M = Mooneye_utils.Make(Mbc2)
+
+let%expect_test "bits_ramg.gb" =
+  M.run_test_rom_and_print_framebuffer "mbc2/bits_ramg.gb";
+
+  [%expect{|
+    A:$00 F:ZN-C BC:$0305 DE:$080D HL:$1522 SP:$E000 PC:$4989
+    008:-#######-----------------------------------###---#---#----------------------------------------------------------------------------------------------------------
+    009:----#-----####-----###-----#--------------#---#--#--#-----------------------------------------------------------------------------------------------------------
+    010:----#----#----#---#-------####------------#---#--#-#------------------------------------------------------------------------------------------------------------
+    011:----#----######----##------#--------------#---#--###------------------------------------------------------------------------------------------------------------
+    012:----#----#-----------#-----#--------------#---#--#--#-----------------------------------------------------------------------------------------------------------
+    013:----#-----####----###------##--------------###---#---#---------------------------------------------------------------------------------------------------------- |}]
+
+let%expect_test "bits_romb.gb" =
+  M.run_test_rom_and_print_framebuffer "mbc2/bits_romb.gb";
+
+  [%expect{|
+    A:$00 F:ZN-C BC:$0305 DE:$080D HL:$1522 SP:$E000 PC:$4879
+    008:-#######-----------------------------------###---#---#----------------------------------------------------------------------------------------------------------
+    009:----#-----####-----###-----#--------------#---#--#--#-----------------------------------------------------------------------------------------------------------
+    010:----#----#----#---#-------####------------#---#--#-#------------------------------------------------------------------------------------------------------------
+    011:----#----######----##------#--------------#---#--###------------------------------------------------------------------------------------------------------------
+    012:----#----#-----------#-----#--------------#---#--#--#-----------------------------------------------------------------------------------------------------------
+    013:----#-----####----###------##--------------###---#---#---------------------------------------------------------------------------------------------------------- |}]
+
+let%expect_test "bits_unused.gb" =
+  M.run_test_rom_and_print_framebuffer "mbc2/bits_unused.gb";
+
+  [%expect{|
+    A:$00 F:ZN-C BC:$0305 DE:$080D HL:$1522 SP:$E000 PC:$4089
+    008:-#######-----------------------------------###---#---#----------------------------------------------------------------------------------------------------------
+    009:----#-----####-----###-----#--------------#---#--#--#-----------------------------------------------------------------------------------------------------------
+    010:----#----#----#---#-------####------------#---#--#-#------------------------------------------------------------------------------------------------------------
+    011:----#----######----##------#--------------#---#--###------------------------------------------------------------------------------------------------------------
+    012:----#----#-----------#-----#--------------#---#--#--#-----------------------------------------------------------------------------------------------------------
+    013:----#-----####----###------##--------------###---#---#---------------------------------------------------------------------------------------------------------- |}]
+
+let%expect_test "ram.gb" =
+  M.run_test_rom_and_print_framebuffer "mbc2/ram.gb";
+
+  [%expect{|
+    A:$00 F:ZN-C BC:$0305 DE:$080D HL:$1522 SP:$E000 PC:$4879
+    008:-#######-----------------------------------###---#---#----------------------------------------------------------------------------------------------------------
+    009:----#-----####-----###-----#--------------#---#--#--#-----------------------------------------------------------------------------------------------------------
+    010:----#----#----#---#-------####------------#---#--#-#------------------------------------------------------------------------------------------------------------
+    011:----#----######----##------#--------------#---#--###------------------------------------------------------------------------------------------------------------
+    012:----#----#-----------#-----#--------------#---#--#--#-----------------------------------------------------------------------------------------------------------
+    013:----#-----####----###------##--------------###---#---#---------------------------------------------------------------------------------------------------------- |}]
+
+let%expect_test "rom_512kb.gb" =
+  M.run_test_rom_and_print_framebuffer "mbc2/rom_512kb.gb";
+
+  [%expect{|
+    A:$00 F:ZN-C BC:$0305 DE:$080D HL:$1522 SP:$E000 PC:$487A
+    008:-#######-----------------------------------###---#---#----------------------------------------------------------------------------------------------------------
+    009:----#-----####-----###-----#--------------#---#--#--#-----------------------------------------------------------------------------------------------------------
+    010:----#----#----#---#-------####------------#---#--#-#------------------------------------------------------------------------------------------------------------
+    011:----#----######----##------#--------------#---#--###------------------------------------------------------------------------------------------------------------
+    012:----#----#-----------#-----#--------------#---#--#--#-----------------------------------------------------------------------------------------------------------
+    013:----#-----####----###------##--------------###---#---#---------------------------------------------------------------------------------------------------------- |}]
+
+let%expect_test "rom_1Mb.gb" =
+  M.run_test_rom_and_print_framebuffer "mbc2/rom_1Mb.gb";
+
+  [%expect{|
+    A:$00 F:ZN-C BC:$0305 DE:$080D HL:$1522 SP:$E000 PC:$487A
+    008:-#######-----------------------------------###---#---#----------------------------------------------------------------------------------------------------------
+    009:----#-----####-----###-----#--------------#---#--#--#-----------------------------------------------------------------------------------------------------------
+    010:----#----#----#---#-------####------------#---#--#-#------------------------------------------------------------------------------------------------------------
+    011:----#----######----##------#--------------#---#--###------------------------------------------------------------------------------------------------------------
+    012:----#----#-----------#-----#--------------#---#--#--#-----------------------------------------------------------------------------------------------------------
+    013:----#-----####----###------##--------------###---#---#---------------------------------------------------------------------------------------------------------- |}]
+
+let%expect_test "rom_2Mb.gb" =
+  M.run_test_rom_and_print_framebuffer "mbc2/rom_2Mb.gb";
+
+  [%expect{|
+    A:$00 F:ZN-C BC:$0305 DE:$080D HL:$1522 SP:$E000 PC:$487A
+    008:-#######-----------------------------------###---#---#----------------------------------------------------------------------------------------------------------
+    009:----#-----####-----###-----#--------------#---#--#--#-----------------------------------------------------------------------------------------------------------
+    010:----#----#----#---#-------####------------#---#--#-#------------------------------------------------------------------------------------------------------------
+    011:----#----######----##------#--------------#---#--###------------------------------------------------------------------------------------------------------------
+    012:----#----#-----------#-----#--------------#---#--#--#-----------------------------------------------------------------------------------------------------------
+    013:----#-----####----###------##--------------###---#---#---------------------------------------------------------------------------------------------------------- |}]