diff --git a/Makefile b/Makefile
index 6000863..7e81eb2 100644
--- a/Makefile
+++ b/Makefile
@@ -31,6 +31,7 @@ NESE_SRC_SRCS = f6502.c f6502_opcodes.c
 NESE_SRC_SRCS += nese.c nes.c cart.c mapper.c
 NESE_SRC_SRCS += ppu.c apu.c
 NESE_SRC_SRCS += memory.c serdes.c save.c rle.c
+NESE_SRC_SRCS += overlay.c
 NESE_SRC_SRCS += $(OS)/port.c
 NESE_MAP_SRCS = $(notdir $(wildcard $(MAPDIR)/*.c))
 
diff --git a/src/charbits.h b/src/charbits.h
new file mode 100644
index 0000000..205defd
--- /dev/null
+++ b/src/charbits.h
@@ -0,0 +1,147 @@
+static const char chars[] = "\x7f!\"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`{|}~";
+
+static const int char_w = 10U;
+static const int char_h = 10U;
+static const int charbit_size = (1U + ((char_w * char_h * 2) + 7) / 8);
+static const int char_count = (sizeof(chars) - 1);
+
+static const uint8_t charbits[1794] = {
+    0x09, 0x55, 0x55, 0x90, 0xaa, 0x16, 0x59, 0x69, 0x91, 0xa5, 0x16, 0x99, 0x66,
+    0x91, 0x5a, 0x16, 0x69, 0x65, 0x91, 0xaa, 0x16, 0x55, 0x55, 0x41, 0x55, 0x15,
+    0x07, 0x50, 0x05, 0x00, 0x69, 0x01, 0x94, 0x16, 0x40, 0x6a, 0x01, 0xa4, 0x15,
+    0x40, 0x5a, 0x01, 0x55, 0x05, 0x90, 0x56, 0x00, 0x55, 0x01, 0x40, 0x15, 0x00,
+    0x08, 0x55, 0x15, 0x90, 0xa6, 0x05, 0x69, 0x5a, 0x90, 0xa6, 0x05, 0x55, 0x55,
+    0x40, 0x55, 0x05, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+    0x0a, 0x54, 0x55, 0x40, 0x9a, 0x16, 0xa5, 0x69, 0x91, 0xaa, 0x5a, 0xa5, 0x69,
+    0x95, 0xaa, 0x5a, 0xa5, 0x69, 0x45, 0x9a, 0x56, 0x54, 0x55, 0x01, 0x55, 0x15,
+    0x09, 0x50, 0x05, 0x40, 0x69, 0x05, 0xa5, 0x6a, 0x91, 0x56, 0x15, 0xa5, 0x5a,
+    0x51, 0x95, 0x16, 0xa9, 0x5a, 0x51, 0x69, 0x15, 0x54, 0x55, 0x00, 0x55, 0x01,
+    0x0a, 0x00, 0x00, 0x50, 0x45, 0x15, 0x69, 0xa5, 0x95, 0x96, 0x56, 0x55, 0x5a,
+    0x45, 0x69, 0x15, 0xa5, 0xa5, 0x95, 0x56, 0x5a, 0x55, 0x55, 0x45, 0x15, 0x55,
+    0x0a, 0x50, 0x15, 0x40, 0xa9, 0x05, 0xa4, 0x69, 0x41, 0x9a, 0x16, 0xa5, 0x5a,
+    0x91, 0x96, 0x5a, 0x69, 0x6a, 0x55, 0x6a, 0x5a, 0x54, 0x55, 0x05, 0x55, 0x55,
+    0x05, 0x55, 0x00, 0x90, 0x16, 0x00, 0x69, 0x01, 0x90, 0x16, 0x00, 0x55, 0x01,
+    0x40, 0x15, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+    0x06, 0x54, 0x01, 0x50, 0x5a, 0x00, 0x69, 0x05, 0x90, 0x56, 0x00, 0x69, 0x01,
+    0x90, 0x16, 0x00, 0x69, 0x01, 0x50, 0x5a, 0x00, 0x54, 0x05, 0x00, 0x55, 0x00,
+    0x06, 0x55, 0x00, 0x90, 0x16, 0x00, 0xa5, 0x05, 0x40, 0x5a, 0x00, 0xa4, 0x05,
+    0x40, 0x5a, 0x00, 0xa5, 0x05, 0x90, 0x56, 0x00, 0x55, 0x01, 0x40, 0x05, 0x00,
+    0x0a, 0x00, 0x00, 0x40, 0x55, 0x05, 0xa4, 0x69, 0x51, 0xa9, 0x15, 0xa9, 0xaa,
+    0x55, 0xa9, 0x55, 0xa4, 0x69, 0x45, 0x55, 0x15, 0x50, 0x55, 0x01, 0x00, 0x00,
+    0x06, 0x00, 0x00, 0x00, 0x00, 0x00, 0x54, 0x00, 0x50, 0x16, 0x00, 0xa9, 0x05,
+    0x50, 0x56, 0x00, 0x54, 0x05, 0x00, 0x15, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+    0x06, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x54, 0x01,
+    0x40, 0x5a, 0x00, 0xa5, 0x05, 0x90, 0x56, 0x00, 0x55, 0x05, 0x40, 0x15, 0x00,
+    0x06, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x50, 0x15, 0x00, 0xa9, 0x05,
+    0x50, 0x55, 0x00, 0x54, 0x05, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+    0x06, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+    0x40, 0x15, 0x00, 0xa4, 0x05, 0x40, 0x5a, 0x00, 0x54, 0x05, 0x00, 0x55, 0x00,
+    0x07, 0x50, 0x05, 0x00, 0x69, 0x01, 0x94, 0x16, 0x40, 0x5a, 0x01, 0xa4, 0x05,
+    0x50, 0x5a, 0x00, 0x69, 0x05, 0x90, 0x16, 0x00, 0x55, 0x01, 0x40, 0x15, 0x00,
+    0x0a, 0x54, 0x55, 0x50, 0xaa, 0x16, 0x69, 0xa5, 0x95, 0x96, 0x5a, 0x69, 0xa6,
+    0x95, 0x5a, 0x5a, 0x69, 0xa5, 0x55, 0xaa, 0x56, 0x54, 0x55, 0x05, 0x55, 0x15,
+    0x09, 0x50, 0x05, 0x40, 0x69, 0x01, 0xa4, 0x16, 0x40, 0x69, 0x01, 0x90, 0x16,
+    0x00, 0x69, 0x01, 0x95, 0x56, 0x90, 0xaa, 0x16, 0x55, 0x55, 0x41, 0x55, 0x15,
+    0x0a, 0x54, 0x55, 0x50, 0xaa, 0x16, 0x69, 0xa5, 0x95, 0x96, 0x5a, 0x55, 0x6a,
+    0x45, 0xa9, 0x55, 0xa5, 0x56, 0x91, 0xaa, 0x5a, 0x55, 0x55, 0x45, 0x55, 0x55,
+    0x0a, 0x54, 0x55, 0x50, 0xaa, 0x16, 0x69, 0xa5, 0x55, 0x55, 0x5a, 0x54, 0x6a,
+    0x55, 0x55, 0x5a, 0x69, 0xa5, 0x55, 0xaa, 0x56, 0x54, 0x55, 0x05, 0x55, 0x15,
+    0x0a, 0x00, 0x55, 0x00, 0x94, 0x16, 0x50, 0x6a, 0x41, 0xa9, 0x16, 0xa5, 0x69,
+    0x91, 0x96, 0x16, 0xa9, 0xaa, 0x55, 0x95, 0x56, 0x54, 0x55, 0x05, 0x40, 0x15,
+    0x0a, 0x55, 0x55, 0x95, 0xaa, 0x5a, 0x69, 0x55, 0x95, 0xaa, 0x56, 0x55, 0xa5,
+    0x55, 0x55, 0x5a, 0x69, 0xa5, 0x55, 0xaa, 0x56, 0x54, 0x55, 0x05, 0x55, 0x15,
+    0x0a, 0x50, 0x15, 0x40, 0xa9, 0x05, 0xa5, 0x55, 0x90, 0x56, 0x05, 0xa9, 0x6a,
+    0x91, 0x56, 0x5a, 0x69, 0xa5, 0x55, 0xaa, 0x56, 0x54, 0x55, 0x05, 0x55, 0x15,
+    0x0a, 0x55, 0x55, 0x91, 0xaa, 0x5a, 0x55, 0x69, 0x45, 0x95, 0x56, 0x40, 0x5a,
+    0x01, 0xa5, 0x15, 0x90, 0x56, 0x00, 0x69, 0x05, 0x50, 0x15, 0x00, 0x54, 0x01,
+    0x0a, 0x54, 0x55, 0x50, 0xaa, 0x16, 0x69, 0xa5, 0x95, 0x5a, 0x5a, 0xa5, 0x6a,
+    0x95, 0x96, 0x5a, 0x69, 0xa5, 0x55, 0xaa, 0x56, 0x54, 0x55, 0x05, 0x55, 0x15,
+    0x0a, 0x54, 0x55, 0x50, 0xaa, 0x16, 0x69, 0xa5, 0x95, 0x56, 0x5a, 0xa5, 0xaa,
+    0x45, 0x55, 0x5a, 0x50, 0x69, 0x05, 0xa9, 0x55, 0x50, 0x55, 0x01, 0x54, 0x05,
+    0x05, 0x00, 0x00, 0x50, 0x05, 0x00, 0x69, 0x01, 0x90, 0x16, 0x00, 0x55, 0x01,
+    0x90, 0x16, 0x00, 0x69, 0x01, 0x50, 0x15, 0x00, 0x54, 0x01, 0x00, 0x00, 0x00,
+    0x06, 0x00, 0x00, 0x40, 0x15, 0x00, 0xa4, 0x05, 0x40, 0x5a, 0x00, 0x54, 0x05,
+    0x40, 0x5a, 0x00, 0xa5, 0x05, 0x90, 0x56, 0x00, 0x55, 0x05, 0x40, 0x15, 0x00,
+    0x08, 0x40, 0x15, 0x00, 0xa5, 0x05, 0x94, 0x56, 0x50, 0x5a, 0x05, 0x69, 0x15,
+    0x50, 0x5a, 0x00, 0x94, 0x16, 0x00, 0xa5, 0x05, 0x40, 0x55, 0x00, 0x50, 0x05,
+    0x06, 0x00, 0x00, 0x00, 0x00, 0x00, 0x55, 0x01, 0x90, 0x5a, 0x00, 0x55, 0x05,
+    0x90, 0x5a, 0x00, 0x55, 0x05, 0x40, 0x55, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+    0x08, 0x55, 0x00, 0x90, 0x16, 0x00, 0xa5, 0x05, 0x40, 0x69, 0x01, 0x50, 0x5a,
+    0x40, 0x69, 0x05, 0xa5, 0x55, 0x90, 0x56, 0x01, 0x55, 0x05, 0x40, 0x15, 0x00,
+    0x0a, 0x54, 0x55, 0x50, 0xaa, 0x16, 0x69, 0xa5, 0x55, 0x55, 0x5a, 0x54, 0x6a,
+    0x05, 0x69, 0x55, 0x50, 0x55, 0x01, 0x69, 0x01, 0x50, 0x15, 0x00, 0x54, 0x01,
+    0x0a, 0x54, 0x55, 0x50, 0xaa, 0x16, 0x69, 0xa5, 0x95, 0xa9, 0x59, 0x99, 0x99,
+    0x95, 0xa9, 0x5a, 0x69, 0x55, 0x55, 0xaa, 0x56, 0x54, 0x55, 0x01, 0x55, 0x15,
+    0x0a, 0x54, 0x55, 0x50, 0xaa, 0x16, 0x69, 0xa5, 0x95, 0x56, 0x5a, 0x69, 0xa5,
+    0x95, 0xaa, 0x5a, 0x69, 0xa5, 0x95, 0x56, 0x5a, 0x55, 0x55, 0x45, 0x15, 0x55,
+    0x0a, 0x55, 0x55, 0x90, 0xaa, 0x16, 0x69, 0xa5, 0x95, 0x56, 0x5a, 0xa9, 0x6a,
+    0x95, 0x56, 0x5a, 0x69, 0xa5, 0x95, 0xaa, 0x56, 0x55, 0x55, 0x45, 0x55, 0x15,
+    0x0a, 0x54, 0x55, 0x50, 0xaa, 0x16, 0x69, 0xa5, 0x95, 0x56, 0x55, 0x69, 0x55,
+    0x95, 0x56, 0x15, 0x69, 0xa5, 0x55, 0xaa, 0x56, 0x54, 0x55, 0x05, 0x55, 0x15,
+    0x0a, 0x55, 0x15, 0x90, 0xaa, 0x05, 0x69, 0x69, 0x91, 0x56, 0x5a, 0x69, 0xa5,
+    0x95, 0x56, 0x5a, 0x69, 0x69, 0x95, 0xaa, 0x55, 0x55, 0x55, 0x41, 0x55, 0x05,
+    0x0a, 0x55, 0x55, 0x91, 0xaa, 0x5a, 0x69, 0x55, 0x95, 0x56, 0x55, 0xa9, 0x6a,
+    0x91, 0x56, 0x15, 0x69, 0x55, 0x91, 0xaa, 0x5a, 0x55, 0x55, 0x45, 0x55, 0x55,
+    0x0a, 0x55, 0x55, 0x91, 0xaa, 0x5a, 0x69, 0x55, 0x95, 0x56, 0x55, 0xa9, 0x6a,
+    0x91, 0x56, 0x15, 0x69, 0x55, 0x91, 0x16, 0x00, 0x55, 0x01, 0x40, 0x15, 0x00,
+    0x0a, 0x54, 0x55, 0x50, 0xaa, 0x16, 0x69, 0xa5, 0x95, 0x56, 0x55, 0x69, 0xa9,
+    0x95, 0x56, 0x5a, 0x69, 0xa5, 0x55, 0xaa, 0x59, 0x54, 0x55, 0x05, 0x55, 0x55,
+    0x0a, 0x55, 0x54, 0x91, 0x56, 0x5a, 0x69, 0xa5, 0x95, 0x56, 0x5a, 0xa9, 0xaa,
+    0x95, 0x56, 0x5a, 0x69, 0xa5, 0x95, 0x56, 0x5a, 0x55, 0x55, 0x45, 0x15, 0x55,
+    0x05, 0x55, 0x00, 0x90, 0x16, 0x00, 0x69, 0x01, 0x90, 0x16, 0x00, 0x69, 0x01,
+    0x90, 0x16, 0x00, 0x69, 0x01, 0x90, 0x16, 0x00, 0x55, 0x01, 0x40, 0x15, 0x00,
+    0x0a, 0x00, 0x54, 0x01, 0x40, 0x5a, 0x00, 0xa4, 0x05, 0x40, 0x5a, 0x55, 0xa5,
+    0x95, 0x56, 0x5a, 0x69, 0xa5, 0x55, 0xaa, 0x56, 0x54, 0x55, 0x05, 0x55, 0x15,
+    0x0a, 0x55, 0x54, 0x91, 0x56, 0x5a, 0x69, 0x69, 0x95, 0xa6, 0x55, 0xa9, 0x56,
+    0x91, 0xa6, 0x05, 0x69, 0x69, 0x91, 0x56, 0x5a, 0x55, 0x55, 0x45, 0x15, 0x55,
+    0x09, 0x55, 0x00, 0x90, 0x16, 0x00, 0x69, 0x01, 0x90, 0x16, 0x00, 0x69, 0x01,
+    0x90, 0x16, 0x00, 0x69, 0x55, 0x90, 0xaa, 0x16, 0x55, 0x55, 0x41, 0x55, 0x15,
+    0x0a, 0x55, 0x54, 0x91, 0x56, 0x5a, 0xa9, 0xa9, 0x95, 0xaa, 0x5a, 0x69, 0xa6,
+    0x95, 0x56, 0x5a, 0x69, 0xa5, 0x95, 0x56, 0x5a, 0x55, 0x55, 0x45, 0x15, 0x55,
+    0x0a, 0x55, 0x54, 0x91, 0x56, 0x5a, 0xa9, 0xa5, 0x95, 0x6a, 0x5a, 0x69, 0xaa,
+    0x95, 0x96, 0x5a, 0x69, 0xa5, 0x95, 0x56, 0x5a, 0x55, 0x55, 0x45, 0x15, 0x55,
+    0x0a, 0x54, 0x55, 0x50, 0xaa, 0x16, 0x69, 0xa5, 0x95, 0x56, 0x5a, 0x69, 0xa5,
+    0x95, 0x56, 0x5a, 0x69, 0xa5, 0x55, 0xaa, 0x56, 0x54, 0x55, 0x05, 0x55, 0x15,
+    0x0a, 0x55, 0x55, 0x90, 0xaa, 0x16, 0x69, 0xa5, 0x95, 0x56, 0x5a, 0x69, 0xa5,
+    0x95, 0xaa, 0x56, 0x69, 0x55, 0x95, 0x56, 0x15, 0x55, 0x01, 0x40, 0x15, 0x00,
+    0x0a, 0x54, 0x55, 0x50, 0xaa, 0x16, 0x69, 0xa5, 0x95, 0x56, 0x5a, 0x69, 0xa5,
+    0x95, 0x56, 0x5a, 0x69, 0x69, 0x55, 0xaa, 0x5a, 0x54, 0x55, 0x05, 0x55, 0x55,
+    0x0a, 0x55, 0x55, 0x90, 0xaa, 0x16, 0x69, 0xa5, 0x95, 0x56, 0x5a, 0xa9, 0x6a,
+    0x95, 0x56, 0x5a, 0x69, 0xa5, 0x95, 0x56, 0x5a, 0x55, 0x55, 0x45, 0x15, 0x55,
+    0x0a, 0x54, 0x55, 0x50, 0xaa, 0x16, 0x69, 0xa5, 0x95, 0x56, 0x55, 0xa5, 0x6a,
+    0x55, 0x55, 0x5a, 0x69, 0xa5, 0x55, 0xaa, 0x56, 0x54, 0x55, 0x05, 0x55, 0x15,
+    0x09, 0x55, 0x55, 0x90, 0xaa, 0x16, 0x95, 0x56, 0x01, 0x69, 0x15, 0x90, 0x16,
+    0x00, 0x69, 0x01, 0x90, 0x16, 0x00, 0x69, 0x01, 0x50, 0x15, 0x00, 0x54, 0x01,
+    0x0a, 0x55, 0x54, 0x91, 0x56, 0x5a, 0x69, 0xa5, 0x95, 0x56, 0x5a, 0x69, 0xa5,
+    0x95, 0x56, 0x5a, 0x69, 0xa5, 0x55, 0xaa, 0x56, 0x54, 0x55, 0x05, 0x55, 0x15,
+    0x0a, 0x55, 0x54, 0x91, 0x56, 0x5a, 0x69, 0xa5, 0x95, 0x56, 0x5a, 0x69, 0xa5,
+    0x55, 0x9a, 0x56, 0x94, 0x5a, 0x05, 0x65, 0x15, 0x40, 0x55, 0x00, 0x50, 0x01,
+    0x0a, 0x55, 0x54, 0x91, 0x56, 0x5a, 0x69, 0xa5, 0x95, 0x56, 0x5a, 0x69, 0xa6,
+    0x95, 0xaa, 0x5a, 0xa9, 0xa9, 0x95, 0x56, 0x5a, 0x55, 0x55, 0x45, 0x15, 0x55,
+    0x0a, 0x55, 0x54, 0x91, 0x56, 0x5a, 0xa9, 0xa9, 0x55, 0xaa, 0x56, 0x94, 0x5a,
+    0x55, 0xaa, 0x16, 0xa9, 0xa9, 0x95, 0x56, 0x5a, 0x55, 0x55, 0x45, 0x15, 0x55,
+    0x09, 0x55, 0x55, 0x90, 0x96, 0x16, 0x69, 0x69, 0x91, 0x96, 0x16, 0xa5, 0x5a,
+    0x41, 0x69, 0x15, 0x90, 0x56, 0x00, 0x69, 0x01, 0x50, 0x15, 0x00, 0x54, 0x01,
+    0x0a, 0x55, 0x55, 0x91, 0xaa, 0x5a, 0x55, 0xa9, 0x05, 0xa5, 0x56, 0x94, 0x5a,
+    0x55, 0x6a, 0x15, 0xa9, 0x55, 0x91, 0xaa, 0x5a, 0x55, 0x55, 0x45, 0x55, 0x55,
+    0x06, 0x55, 0x01, 0x90, 0x5a, 0x00, 0x69, 0x05, 0x90, 0x56, 0x00, 0x69, 0x01,
+    0x90, 0x16, 0x00, 0x69, 0x01, 0x90, 0x5a, 0x00, 0x55, 0x05, 0x40, 0x55, 0x00,
+    0x07, 0x55, 0x00, 0x90, 0x16, 0x00, 0x69, 0x01, 0x50, 0x5a, 0x00, 0xa4, 0x05,
+    0x40, 0x5a, 0x00, 0x94, 0x16, 0x00, 0x69, 0x01, 0x50, 0x15, 0x00, 0x54, 0x01,
+    0x06, 0x55, 0x01, 0x90, 0x5a, 0x00, 0xa5, 0x05, 0x40, 0x5a, 0x00, 0xa4, 0x05,
+    0x40, 0x5a, 0x00, 0xa5, 0x05, 0x90, 0x5a, 0x00, 0x55, 0x05, 0x40, 0x55, 0x00,
+    0x08, 0x50, 0x01, 0x40, 0x59, 0x00, 0xa5, 0x16, 0x90, 0xa6, 0x05, 0x59, 0x59,
+    0x50, 0x55, 0x05, 0x54, 0x54, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+    0x0a, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+    0x00, 0x00, 0x00, 0x55, 0x55, 0x91, 0xaa, 0x5a, 0x55, 0x55, 0x45, 0x55, 0x55,
+    0x07, 0x55, 0x00, 0x90, 0x16, 0x00, 0xa5, 0x05, 0x40, 0x69, 0x01, 0x50, 0x15,
+    0x00, 0x54, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+    0x07, 0x50, 0x05, 0x40, 0x69, 0x01, 0xa4, 0x15, 0x50, 0x5a, 0x01, 0x69, 0x05,
+    0x50, 0x5a, 0x00, 0xa4, 0x05, 0x40, 0x69, 0x01, 0x50, 0x15, 0x00, 0x54, 0x01,
+    0x04, 0x15, 0x00, 0x90, 0x05, 0x00, 0x59, 0x00, 0x90, 0x05, 0x00, 0x59, 0x00,
+    0x90, 0x05, 0x00, 0x59, 0x00, 0x90, 0x05, 0x00, 0x55, 0x00, 0x40, 0x05, 0x00,
+    0x07, 0x55, 0x00, 0x90, 0x16, 0x00, 0xa5, 0x05, 0x40, 0x5a, 0x00, 0x94, 0x16,
+    0x40, 0x5a, 0x01, 0xa5, 0x15, 0x90, 0x56, 0x00, 0x55, 0x05, 0x40, 0x15, 0x00,
+    0x0a, 0x00, 0x00, 0x00, 0x00, 0x00, 0x54, 0x55, 0x51, 0x6a, 0x5a, 0x69, 0x6a,
+    0x55, 0x55, 0x55, 0x54, 0x55, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+};
diff --git a/src/linux/port.c b/src/linux/port.c
index f63283d..8aee815 100644
--- a/src/linux/port.c
+++ b/src/linux/port.c
@@ -12,6 +12,7 @@
 
 #include "cart.h"
 #include "nese.h"
+#include "overlay.h"
 #include "port.h"
 #include "save.h"
 
@@ -98,6 +99,8 @@ typedef struct {
     SDL_Texture* texture;
     SDL_Surface* target;
     SDL_Surface* screen;
+    SDL_Rect view;
+    Overlay overlay;
 } platform_data;
 
 
@@ -309,7 +312,9 @@ int nese_frame_ready(void* plat_data) {
     SDL_LockTextureToSurface(plat->texture, NULL,
                              &plat->target);
 
-    // TODO: Overlay
+    overlay_render(&plat->overlay,
+                   nes_ppu_render_w, nes_ppu_render_h,
+                   &plat->view, plat->renderer);
 
     SDL_RenderPresent(plat->renderer);
 
@@ -357,12 +362,15 @@ static int plat_init(platform_data* plat) {
         );
 
     if (0 == status) {
+        plat->view = (SDL_Rect){
+            .w = nes_ppu_render_w * 8,
+            .h = nes_ppu_render_h * 7,
+        };
         plat->window = SDL_CreateWindow(
                 "NESe",
                 SDL_WINDOWPOS_CENTERED,
                 SDL_WINDOWPOS_CENTERED,
-                nes_ppu_render_w * 8,
-                nes_ppu_render_h * 7,
+                plat->view.w, plat->view.h,
                 0
             );
         if (NULL == plat->window) {
@@ -418,6 +426,10 @@ static int plat_init(platform_data* plat) {
         }
     }
 
+    if (0 == status) {
+        status = overlay_init(&plat->overlay, plat->renderer);
+    }
+
     if (0 == status) {
         plat->t_target = time_now();
     }
@@ -429,6 +441,7 @@ static void plat_done(platform_data* plat) {
     if (NULL != plat->texture) SDL_DestroyTexture(plat->texture);
     if (NULL != plat->renderer) SDL_DestroyRenderer(plat->renderer);
     if (NULL != plat->window) SDL_DestroyWindow(plat->window);
+    overlay_done(&plat->overlay);
     SDL_Quit();
 }
 
diff --git a/src/overlay.c b/src/overlay.c
new file mode 100644
index 0000000..d584af1
--- /dev/null
+++ b/src/overlay.c
@@ -0,0 +1,280 @@
+#include <stdint.h>
+
+#include "charbits.h"
+#include "overlay.h"
+
+
+/* Font */
+
+typedef struct {
+    const uint8_t* bits;
+    uint8_t shift;
+} bit_buffer;
+
+static void make_bit_buffer(bit_buffer* buf,
+                            const uint8_t* bits) {
+    buf->bits = bits;
+    buf->shift = 0;
+}
+
+static uint8_t get_bits(bit_buffer* buf) {
+    uint8_t val = ((buf->bits[0] >> buf->shift) & 3);
+    if (buf->shift == 6) {
+        buf->shift = 0;
+        buf->bits++;
+    } else {
+        buf->shift += 2;
+    }
+    return val;
+}
+
+static const SDL_Color pal[2] = {
+    {0, 0, 0, 255}, {255, 255, 255, 255}
+};
+
+static SDL_Surface* create_char_surface(const uint8_t* bits) {
+    int w = *bits++;
+    bit_buffer buf = {0};
+    make_bit_buffer(&buf, bits);
+
+    SDL_Surface* surface = SDL_CreateRGBSurfaceWithFormat(
+            0, w, char_h, 8, SDL_PIXELFORMAT_INDEX8
+        );
+    SDL_SetPaletteColors(surface->format->palette, pal, 1U, 2U);
+    SDL_SetColorKey(surface, SDL_TRUE, 0);
+
+    uint8_t* line = surface->pixels;
+    for (int y = char_h; y > 0; --y) {
+        uint8_t* dst = line;
+        for (int x = w; x > 0; --x) {
+            *dst++ = get_bits(&buf);
+        }
+        for (int x = (char_w - w); x > 0; --x) get_bits(&buf);
+        line += surface->pitch;
+    }
+
+    return surface;
+}
+
+static SDL_Texture* create_char_texture(SDL_Renderer* rend,
+                                        const uint8_t* bits) {
+    SDL_Surface* surface = create_char_surface(bits);
+    SDL_SetSurfaceBlendMode(surface, SDL_BLENDMODE_NONE);
+    SDL_Texture* texture = SDL_CreateTextureFromSurface(
+            rend, surface
+        );
+    SDL_FreeSurface(surface);
+    return texture;
+}
+
+int overlay_font_init(Overlay_font* font, SDL_Renderer* rend) {
+    font->chars = chars;
+    font->charbits = charbits;
+    font->char_count = char_count;
+    font->textures = calloc(char_count, sizeof(SDL_Texture*));
+    if (NULL != font->textures) {
+        for (int i = 0; i < font->char_count; ++i) {
+            font->textures[i] = create_char_texture(
+                    rend, &font->charbits[i * charbit_size]
+                );
+        }
+    }
+    return (NULL != font->textures) ? 0 : -1;
+}
+
+void overlay_font_done(Overlay_font* font) {
+    for (int i = 0; i < font->char_count; ++i) {
+        SDL_DestroyTexture(font->textures[i]);
+    }
+    free(font->textures);
+    font->textures = NULL;
+}
+
+
+#define overlay_start_x (char_w / 2)
+#define overlay_start_y (char_h / 2)
+
+#define space_width ((char_w / 2) - 1)
+
+static inline int char_index(char c) {
+    if (c >= 'a' && c <= 'z') c += ('A' - 'a');
+    if (c > ' ' && c < 'a') return (c - ' ');
+    if (c >= '{' && c <= '~') return (65 + c - '{');
+    return 0;
+}
+
+void overlay_font_measure(const Overlay_font* font,
+                          const char* string,
+                          int* w, int* h) {
+    *h = char_h;
+    int max_w = 1;
+    int cur_w = 1;
+    for (const char* c = string; *c; ++c) {
+        if (*c == '\n') {
+            if (cur_w > max_w) max_w = cur_w;
+            cur_w = 1;
+            *h += char_h;
+        } else if (*c == ' ') {
+            cur_w += space_width;
+        } else {
+            int index = char_index(*c);
+            int cw = font->charbits[index * charbit_size];
+            cur_w += (cw - 1);
+        }
+    }
+    if (cur_w > max_w) max_w = cur_w;
+    *w = max_w;
+}
+
+void overlay_font_render(Overlay_font* font, const char* string,
+                         const SDL_Rect* target,
+                         const SDL_Rect* view,
+                         uint32_t color, SDL_Renderer *rend) {
+    int x = target->x;
+    int y = target->y;
+    for (const char* c = string; *c; ++c) {
+        if (*c == '\n') {
+            x = target->x;
+            y += (char_h + 1);
+        } else if (*c == ' ') {
+            x += space_width;
+        } else {
+            int index = char_index(*c);
+            int cw = font->charbits[index * charbit_size];
+            SDL_Texture* texture = font->textures[index];
+
+            SDL_Rect rect = {
+                .x = ((x * view->w) / target->w) + view->x,
+                .y = ((y * view->h) / target->h) + view->y,
+                .w = (cw * view->w) / target->w,
+                .h = (char_h * view->h) / target->h,
+            };
+
+            SDL_SetTextureColorMod(
+                    texture,
+                    ((color >> 16) & 0xFFU),
+                    ((color >>  8) & 0xFFU),
+                    ((color >>  0) & 0xFFU)
+                );
+            SDL_SetTextureAlphaMod(texture,
+                                   ((color >> 24) & 0xFFU));
+            SDL_RenderCopy(rend, texture, NULL, &rect);
+
+            x += (cw - 1);
+        }
+    }
+}
+
+
+/* Overlay */
+
+typedef struct Overlay_message_t {
+    char* string;
+    int id;
+    int expiry;
+    struct Overlay_message_t* next;
+} Overlay_message;
+
+
+int overlay_init(Overlay* overlay, SDL_Renderer* rend) {
+    overlay->messages = NULL;
+    overlay->next_id = 0;
+    overlay_font_init(&overlay->font, rend);
+    return 0;
+}
+
+int overlay_clear(Overlay* overlay) {
+    int n_cleared = 0;
+    Overlay_message* next = NULL;
+    for (   Overlay_message* message = overlay->messages;
+            NULL != message;
+            message = next) {
+        next = message->next;
+        free(message->string);
+        free(message);
+        ++n_cleared;
+    }
+    overlay->messages = NULL;
+    return n_cleared;
+}
+
+void overlay_done(Overlay* overlay) {
+    overlay_clear(overlay);
+    overlay_font_done(&overlay->font);
+}
+
+int overlay_clear_message(Overlay* overlay, int id) {
+    int result = -1;
+    Overlay_message* last = NULL;
+    Overlay_message* message = overlay->messages;
+    for (   ;
+            NULL != message && message->id != id;
+            last = message, message = message->next
+        );
+    if (NULL != message) {
+        result = 0;
+        if (NULL == last) {
+            overlay->messages = message->next;
+        } else {
+            last->next = message->next;
+        }
+        free(message->string);
+        free(message);
+    }
+    return result;
+}
+
+int overlay_add_message(Overlay* overlay,
+                        const char* string, int expiry) {
+    Overlay_message* message = calloc(1, sizeof(*message));
+    message->string = strdup(string);
+    message->id     = ++(overlay->next_id);
+    message->expiry = expiry;
+    message->next   = NULL;
+    if (NULL == overlay->messages) {
+        overlay->messages = message;
+    } else {
+        Overlay_message* last = overlay->messages;
+        for ( ; NULL != last->next; last = last->next);
+        last->next = message;
+    }
+    return message->id;
+}
+
+void overlay_render(Overlay* overlay, int w, int h,
+                    const SDL_Rect* view, SDL_Renderer* rend) {
+    SDL_Rect target = {
+        .x = overlay_start_x,
+        .y = overlay_start_y,
+        .w = w,
+        .h = h,
+    };
+    for (   Overlay_message* message = overlay->messages;
+            NULL != message;
+            message = message->next) {
+        overlay_font_render(&overlay->font, message->string,
+                            &target, view,
+                            0xFFFFFFFFU, rend);
+        target.y += (char_h + 1);
+    }
+}
+
+void overlay_step(Overlay* overlay) {
+    Overlay_message* last = NULL, *next = NULL;
+    for (   Overlay_message* message = overlay->messages;
+            NULL != message;
+            message = next) {
+        next = message->next;
+        if (message->expiry > 0 && --(message->expiry) == 0) {
+            if (NULL == last) {
+                overlay->messages = message->next;
+            } else {
+                last->next = message->next;
+            }
+            free(message->string);
+            free(message);
+        } else {
+            last = message;
+        }
+    }
+}
diff --git a/src/overlay.h b/src/overlay.h
new file mode 100644
index 0000000..c5ce5ee
--- /dev/null
+++ b/src/overlay.h
@@ -0,0 +1,47 @@
+#ifndef NESE_OVERLAY_H_
+#define NESE_OVERLAY_H_
+
+#include <SDL.h>
+
+
+typedef struct {
+    const char* chars;
+    const uint8_t* charbits;
+    int char_count;
+    SDL_Texture** textures;
+} Overlay_font;
+
+int overlay_font_init(Overlay_font*, SDL_Renderer*);
+void overlay_font_done(Overlay_font*);
+
+void overlay_font_measure(const Overlay_font*,
+                          const char* string,
+                          int* w, int* h);
+void overlay_font_render(Overlay_font*, const char* string,
+                         const SDL_Rect* target,
+                         const SDL_Rect* view,
+                         uint32_t color, SDL_Renderer*);
+
+
+struct Overlay_message_t;
+
+typedef struct {
+    struct Overlay_message_t* messages;
+    int next_id;
+    Overlay_font font;
+} Overlay;
+
+int overlay_init(Overlay*, SDL_Renderer*);
+void overlay_done(Overlay*);
+
+int overlay_add_message(Overlay*, const char*, int expiry);
+int overlay_clear_message(Overlay*, int id);
+int overlay_clear(Overlay*);
+
+void overlay_step(Overlay*);
+
+void overlay_render(Overlay*, int w, int h,
+                    const SDL_Rect* view, SDL_Renderer*);
+
+
+#endif // NESE_OVERLAY_H_