Merge branch 'dev' into ppu-interface

40 files changed, 2223 insertions, 427 deletions

diff --git a/basys3/basys3.srcs/apu.vhd b/basys3/basys3.srcs/apu.vhd
index 4a594ab..1fff1e8 100644
--- a/basys3/basys3.srcs/apu.vhd
+++ b/basys3/basys3.srcs/apu.vhd
@@ -3,29 +3,29 @@ use ieee.std_logic_1164.all;
 --use ieee.numeric_std.all;
 
 entity apu is port(
-	CLK100: in std_logic; -- system clock
-	RESET: in std_logic; -- global (async) system reset
-	DATA: in std_logic_vector(15 downto 0);
-	SOUND: out std_logic);
+	CLK100 : in std_logic; -- system clock
+	RESET : in std_logic; -- global (async) system reset
+	DATA : in std_logic_vector(15 downto 0);
+	SOUND : out std_logic);
 
-	-- EN: in std_logic; -- PPU VRAM enable (enable ADDR and DATA tri-state drivers)
-	-- WEN: in std_logic; -- PPU VRAM write enable
-	-- ADDR: in std_logic_vector(15 downto 0); -- PPU VRAM ADDR
-	-- R,G,B: out std_logic_vector(3 downto 0);
-	-- NVSYNC, NHSYNC: out std_logic; -- native VGA out
-	-- TVSYNC, TVBLANK, THSYNC, THBLANK: out std_logic); -- tiny VGA out
+	-- EN : in std_logic; -- PPU VRAM enable (enable ADDR and DATA tri-state drivers)
+	-- WEN : in std_logic; -- PPU VRAM write enable
+	-- ADDR : in std_logic_vector(15 downto 0); -- PPU VRAM ADDR
+	-- R,G,B : out std_logic_vector(3 downto 0);
+	-- NVSYNC, NHSYNC : out std_logic; -- native VGA out
+	-- TVSYNC, TVBLANK, THSYNC, THBLANK : out std_logic); -- tiny VGA out
 end apu;
 
 architecture Behavioral of apu is
 	component apu_note_to_frequency port(
-		data: in std_logic_vector(7 downto 0);
-		freq: out std_logic_vector(7 downto 0)); --frequency
+		data : in std_logic_vector(7 downto 0);
+		freq : out std_logic_vector(7 downto 0)); --frequency
 	end component;
 	component apu_LUT_reader port(
-		clk: in std_logic;
-		rst: in std_logic;
-		wave: in std_logic_vector(1 downto 0);
-		level: out std_logic_vector(7 downto 0));
+		clk : in std_logic;
+		rst : in std_logic;
+		wave : in std_logic_vector(1 downto 0);
+		level : out std_logic_vector(7 downto 0));
 	end component;
 begin
 
diff --git a/basys3/basys3.srcs/apu_LUT_reader.vhd b/basys3/basys3.srcs/apu_lut_reader.vhd
index 6039798..2f92eca 100644
--- a/basys3/basys3.srcs/apu_LUT_reader.vhd
+++ b/basys3/basys3.srcs/apu_lut_reader.vhd
@@ -2,7 +2,7 @@ library ieee;
 use ieee.std_logic_1164.all;
 use ieee.numeric_std.all;
 
-entity apu_LUT_reader is
+entity apu_lut_reader is
     port (
         clk : in std_logic;
         rst : in std_logic;
@@ -12,7 +12,7 @@ entity apu_LUT_reader is
     );
 end entity;
 
-architecture Behavioral of apu_LUT_reader is
+architecture behavioral of apu_lut_reader is
 
     constant AMPLITUDE : natural := 0;
     constant SAMPLE_SIZE : natural := 256;
diff --git a/basys3/basys3.srcs/apu_tb_LUT_reader.vhd b/basys3/basys3.srcs/apu_lut_reader_tb.vhd
index 5a38d39..1b425bf 100644
--- a/basys3/basys3.srcs/apu_tb_LUT_reader.vhd
+++ b/basys3/basys3.srcs/apu_lut_reader_tb.vhd
@@ -2,14 +2,14 @@ library ieee;
 use ieee.std_logic_1164.all;
 use ieee.numeric_std.all;
 
-library UNISIM;
-use UNISIM.VComponents.all;
+library unisim;
+use unisim.vcomponents.all;
 
-entity apu_tb_LUT_reader is
+entity apu_lut_reader_tb is
 end entity;
 
-architecture Behavioral of apu_tb_LUT_reader is
-    component apu_LUT_reader is
+architecture Behavioral of apu_lut_reader_tb is
+    component apu_lut_reader is
         port (
             clk   : in std_logic;
             rst : in std_logic;
diff --git a/basys3/basys3.srcs/apu_note_to_frequency.vhd b/basys3/basys3.srcs/apu_note_to_frequency.vhd
index 8a7b3d6..810cef9 100644
--- a/basys3/basys3.srcs/apu_note_to_frequency.vhd
+++ b/basys3/basys3.srcs/apu_note_to_frequency.vhd
@@ -10,9 +10,9 @@ entity apu_note_to_frequency is port (
 end entity;
 
 architecture Behavioral of apu_note_to_frequency is
-	signal buff_small: std_logic_vector(7 downto 0) := (others => '0');
-	signal buff: std_logic_vector(11 downto 0) := (others => '0');
-	signal shift: integer;
+	signal buff_small : std_logic_vector(7 downto 0) := (others => '0');
+	signal buff : std_logic_vector(15 downto 0) := (others => '0');
+	signal shift : integer;
 begin
 
     shift <= to_integer(unsigned( data(2 downto 0) ));
diff --git a/basys3/basys3.srcs/apu_note_to_frequency_tb.vhd b/basys3/basys3.srcs/apu_note_to_frequency_tb.vhd
index 6814c1f..f48a40c 100644
--- a/basys3/basys3.srcs/apu_note_to_frequency_tb.vhd
+++ b/basys3/basys3.srcs/apu_note_to_frequency_tb.vhd
@@ -10,20 +10,20 @@ end entity;
 
 architecture Behavioral of apu_note_to_frequency_tb is
 	component apu_note_to_frequency is port(
-		data: in std_logic_vector(7 downto 0);
-		freq: out std_logic_vector(11 downto 0)); -- frequency
+		data : in std_logic_vector(7 downto 0);
+		freq : out std_logic_vector(11 downto 0)); -- frequency
 	end component;
 
-	signal data: std_logic_vector(7 downto 0) := (others => '0');
-	signal freq: std_logic_vector(11 downto 0) := (others => '0');
+	signal data : std_logic_vector(7 downto 0) := (others => '0');
+	signal freq : std_logic_vector(11 downto 0) := (others => '0');
 
-	signal ok: boolean := false;
+	signal ok : boolean := false;
 begin
-	uut: apu_note_to_frequency port map(
+	uut : apu_note_to_frequency port map(
 		data => data,
 		freq => freq);
 	
-	tb: process
+	tb : process
 	begin
 		for i in 0 to 255 loop
 			data <= std_logic_vector(to_unsigned(i, 8));
diff --git a/basys3/basys3.srcs/er_ram.vhd b/basys3/basys3.srcs/er_ram.vhd
new file mode 100644
index 0000000..66f905b
--- /dev/null
+++ b/basys3/basys3.srcs/er_ram.vhd
@@ -0,0 +1,53 @@
+library ieee;
+library work;
+use ieee.std_logic_1164.all;
+use ieee.numeric_std.all;
+
+entity er_ram is -- exposed register RAM
+	generic(
+		ADDR_W : natural := 2; -- ADDR line width
+		DATA_W : natural := 2; -- DATA line width
+		ADDR_LOW : natural := 16#0000#; -- starting address
+		ADDR_RANGE : natural := 16#0002#); -- amount of valid addresses after ADDR_LOW
+	port(
+		CLK : in std_logic; -- clock
+		RST : in std_logic; -- async memory clear
+		WEN : in std_logic; -- write enable
+		ADDR : in std_logic_vector(ADDR_W-1 downto 0); -- address line
+		DATA : in std_logic_vector(DATA_W-1 downto 0); -- data input
+		REG : out std_logic_vector((ADDR_RANGE*DATA_W)-1 downto 0)); -- exposed register output
+end er_ram;
+
+architecture Behavioral of er_ram is
+	component er_ram_mod
+		generic(
+			W : natural := DATA_W; -- module data width
+			ADDR_W : natural := ADDR_W; -- address width
+			ADDR_M : std_logic_vector(ADDR_W-1 downto 0) := (others => '0')); -- address match
+		port(
+			CLK : in std_logic; -- clock
+			RST : in std_logic; -- async memory clear
+			WEN : in std_logic; -- write enable
+			ADDR : in std_logic_vector(ADDR_W-1 downto 0);
+			DATA : in std_logic_vector(W-1 downto 0); -- data
+			REG : out std_logic_vector(W-1 downto 0)); -- direct register out
+	end component;
+	signal INT_REG : std_logic_vector((ADDR_RANGE*DATA_W)-1 downto 0);
+begin
+	REG <= INT_REG;
+
+	registers : for idx in 0 to ADDR_RANGE - 1 generate
+		reg : component er_ram_mod
+			generic map(
+				W => DATA_W,
+				ADDR_W => ADDR_W,
+				ADDR_M => std_logic_vector(to_unsigned(ADDR_LOW + idx, ADDR_W)))
+			port map(
+				CLK => CLK,
+				RST => RST,
+				WEN => WEN,
+				ADDR => ADDR,
+				DATA => DATA,
+				REG => INT_REG(idx*DATA_W+DATA_W-1 downto idx*DATA_W));
+	end generate;
+end Behavioral;
diff --git a/basys3/basys3.srcs/er_ram_mod.vhd b/basys3/basys3.srcs/er_ram_mod.vhd
new file mode 100644
index 0000000..ae680b1
--- /dev/null
+++ b/basys3/basys3.srcs/er_ram_mod.vhd
@@ -0,0 +1,34 @@
+library ieee;
+library work;
+use ieee.std_logic_1164.all;
+
+entity er_ram_mod is -- exposed register RAM module (single register)
+	generic(
+		W : natural := 1; -- module data width
+		ADDR_W : natural := 1; -- address width
+		ADDR_M : std_logic_vector(ADDR_W-1 downto 0) := (others => '0')); -- address match
+	port(
+		CLK : in std_logic; -- clock
+		RST : in std_logic; -- async memory clear
+		WEN : in std_logic; -- write enable
+		ADDR : in std_logic_vector(ADDR_W-1 downto 0); -- RAM address line
+		DATA : in std_logic_vector(W-1 downto 0); -- RAM input data line
+		REG : out std_logic_vector(W-1 downto 0)); -- direct register output lines
+end er_ram_mod;
+
+architecture Behavioral of er_ram_mod is
+	signal DATA_REG : std_logic_vector(W-1 downto 0);
+begin
+	REG <= DATA_REG;
+
+	process(CLK, RST)
+	begin
+		if RST = '1' then
+			DATA_REG <= (others => '0');
+		elsif rising_edge(CLK) then
+			if WEN = '1' and ADDR = ADDR_M then
+				DATA_REG <= DATA;
+			end if;
+		end if;
+	end process;
+end Behavioral;
diff --git a/basys3/basys3.srcs/er_ram_mod_tb.vhd b/basys3/basys3.srcs/er_ram_mod_tb.vhd
new file mode 100644
index 0000000..aa77a56
--- /dev/null
+++ b/basys3/basys3.srcs/er_ram_mod_tb.vhd
@@ -0,0 +1,81 @@
+library ieee;
+library unisim;
+
+use ieee.std_logic_1164.all;
+use ieee.numeric_std.all;
+use unisim.vcomponents.all;
+
+entity er_ram_mod_tb is
+end er_ram_mod_tb;
+
+architecture behavioral of er_ram_mod_tb is
+	component er_ram_mod
+		generic(
+			W : natural := 1; -- module data width
+			ADDR_W : natural := 1; -- address width
+			ADDR_M : std_logic_vector(ADDR_W-1 downto 0) := (others => '0')); -- address match
+		port(
+			CLK : in std_logic; -- clock
+			RST : in std_logic; -- async memory clear
+			WEN : in std_logic; -- write enable
+			ADDR : in std_logic_vector(ADDR_W-1 downto 0);
+			DATA : in std_logic_vector(W-1 downto 0); -- data
+			REG : out std_logic_vector(W-1 downto 0)); -- direct register out
+	end component;
+
+	signal CLK, RST, WEN : std_logic := '0';
+	signal ADDR : std_logic_vector(3 downto 0);
+	signal DATA : std_logic_vector(7 downto 0);
+	signal REG : std_logic_vector(7 downto 0);
+begin
+	uut : component er_ram_mod
+		generic map(
+			W => 8,
+			ADDR_W => 4,
+			ADDR_M => x"5")
+		port map(
+			CLK => CLK,
+			RST => RST,
+			WEN => WEN,
+			ADDR => ADDR,
+			DATA => DATA,
+			REG => REG);
+
+	tb : process
+	begin
+		wait for 5 ns;
+
+		-- async reset (safety)
+		RST <= '1';
+		wait for 5 ns;
+		RST <= '0';
+		wait for 5 ns;
+
+		-- set 0xef at address 0x5 (exists)
+		DATA <= x"ef";
+		ADDR <= x"5";
+		WEN <= '1';
+
+		CLK <= '1';
+		wait for 5 ns;
+		CLK <= '0';
+		wait for 5 ns;
+
+		-- set 0x34 at address 0x4 (doesn't exist)
+		ADDR <= x"4";
+		DATA <= x"34";
+
+		CLK <= '1';
+		wait for 5 ns;
+		CLK <= '0';
+		wait for 5 ns;
+
+		-- reset
+		RST <= '1';
+		wait for 5 ns;
+		RST <= '0';
+		wait for 5 ns;
+
+		wait; -- stop for simulator
+	end process;
+end;
diff --git a/basys3/basys3.srcs/er_ram_tb.vhd b/basys3/basys3.srcs/er_ram_tb.vhd
new file mode 100644
index 0000000..d360442
--- /dev/null
+++ b/basys3/basys3.srcs/er_ram_tb.vhd
@@ -0,0 +1,116 @@
+library ieee;
+library unisim;
+
+use ieee.std_logic_1164.all;
+use ieee.numeric_std.all;
+use unisim.vcomponents.all;
+
+entity er_ram_tb is
+end er_ram_tb;
+
+architecture behavioral of er_ram_tb is
+	component er_ram
+		generic(
+			ADDR_W : natural := 2; -- ADDR line width
+			DATA_W : natural := 2; -- DATA line width
+			ADDR_LOW : natural := 16#0000#; -- starting address
+			ADDR_RANGE : natural := 16#0002#); -- amount of valid addresses after ADDR_LOW
+		port(
+			CLK : in std_logic; -- clock
+			RST : in std_logic; -- async memory clear
+			WEN : in std_logic; -- write enable
+			ADDR : in std_logic_vector(ADDR_W-1 downto 0);
+			DATA : in std_logic_vector(DATA_W-1 downto 0);
+			REG : out std_logic_vector((ADDR_W*DATA_W)-1 downto 0));
+	end component;
+
+	signal CLK, RST, WEN : std_logic := '0';
+	signal ADDR : std_logic_vector(3 downto 0);
+	signal DATA : std_logic_vector(7 downto 0);
+	signal REG : std_logic_vector(31 downto 0);
+begin
+	uut : component er_ram
+		generic map(
+			ADDR_W => 4,
+			DATA_W => 8,
+			ADDR_LOW => 0,
+			ADDR_RANGE => 4)
+		port map(
+			CLK => CLK,
+			RST => RST,
+			WEN => WEN,
+			ADDR => ADDR,
+			DATA => DATA,
+			REG => REG);
+
+	tb : process
+	begin
+		wait for 5 ns;
+
+		-- async reset (safety)
+		RST <= '1';
+		wait for 5 ns;
+		RST <= '0';
+		wait for 5 ns;
+
+		-- set 0xef at address 0x1 (exists)
+		DATA <= x"ef";
+		ADDR <= x"1";
+		WEN <= '1';
+
+		CLK <= '1';
+		wait for 5 ns;
+		CLK <= '0';
+		wait for 5 ns;
+
+		-- set 0x34 at address 0x4 (doesn't exist)
+		ADDR <= x"4";
+		DATA <= x"34";
+
+		CLK <= '1';
+		wait for 5 ns;
+		CLK <= '0';
+		wait for 5 ns;
+
+		-- reset
+		RST <= '1';
+		wait for 5 ns;
+		RST <= '0';
+		wait for 5 ns;
+
+		-- set REG to 0x12345678
+		ADDR <= x"0";
+		DATA <= x"12";
+
+		CLK <= '1';
+		wait for 1 ns;
+		CLK <= '0';
+		wait for 1 ns;
+
+		ADDR <= x"1";
+		DATA <= x"34";
+
+		CLK <= '1';
+		wait for 1 ns;
+		CLK <= '0';
+		wait for 1 ns;
+
+		ADDR <= x"2";
+		DATA <= x"56";
+
+		CLK <= '1';
+		wait for 1 ns;
+		CLK <= '0';
+		wait for 1 ns;
+
+		ADDR <= x"3";
+		DATA <= x"78";
+
+		CLK <= '1';
+		wait for 1 ns;
+		CLK <= '0';
+		wait for 1 ns;
+
+		wait; -- stop for simulator
+	end process;
+end;
diff --git a/basys3/basys3.srcs/ppu.vhd b/basys3/basys3.srcs/ppu.vhd
index 663f3ab..9cf1bc0 100644
--- a/basys3/basys3.srcs/ppu.vhd
+++ b/basys3/basys3.srcs/ppu.vhd
@@ -6,184 +6,191 @@ use ieee.std_logic_1164.all;
 use work.ppu_consts.all;
 
 entity ppu is port(
-	CLK100: in std_logic; -- system clock
-	RESET: in std_logic; -- global (async) system reset
-	EN: in std_logic; -- PPU VRAM enable (enable ADDR and DATA tri-state drivers)
-	WEN: in std_logic; -- PPU VRAM write enable
-	ADDR: in std_logic_vector(PPU_RAM_BUS_ADDR_WIDTH-1 downto 0); -- PPU VRAM ADDR
-	DATA: in std_logic_vector(PPU_RAM_BUS_DATA_WIDTH-1 downto 0);
-	R,G,B: out std_logic_vector(PPU_COLOR_OUTPUT_DEPTH-1 downto 0);
-	NVSYNC, NHSYNC: out std_logic; -- native VGA out
-	TVSYNC, TVBLANK, THSYNC, THBLANK: out std_logic); -- tiny VGA out
+	CLK100 : in std_logic; -- system clock
+	RESET : in std_logic; -- global (async) system reset
+	EN : in std_logic; -- PPU VRAM enable (enable ADDR and DATA tri-state drivers)
+	WEN : in std_logic; -- PPU VRAM write enable
+	ADDR : in std_logic_vector(PPU_RAM_BUS_ADDR_WIDTH-1 downto 0); -- PPU VRAM ADDR
+	DATA : in std_logic_vector(PPU_RAM_BUS_DATA_WIDTH-1 downto 0);
+	R,G,B : out std_logic_vector(PPU_COLOR_OUTPUT_DEPTH-1 downto 0);
+	NVSYNC, NHSYNC : out std_logic; -- native VGA out
+	TVSYNC, TVBLANK, THSYNC, THBLANK : out std_logic); -- tiny VGA out
 end ppu;
 
 architecture Behavioral of ppu is
+	-- TODO: separate SPRITE_BG and SPRITE_FG lines (foreground_sprite only needs 2 clock cycles)
 	component ppu_pceg port( -- pipeline clock edge generator
-		CLK: in std_logic; -- system clock
-		RESET: in std_logic; -- async reset
-		SPRITE: out std_logic; -- sprite info fetch + sprite pixel fetch
-		COMP_PAL: out std_logic; -- compositor + palette lookup
-		DONE: out std_logic); -- last pipeline stage done
+		CLK : in std_logic; -- system clock
+		RESET : in std_logic; -- async reset
+		SPRITE : out std_logic; -- sprite info fetch + sprite pixel fetch
+		COMP_PAL : out std_logic; -- compositor + palette lookup
+		DONE : out std_logic); -- last pipeline stage done
 	end component;
 	component ppu_addr_dec port( -- pipeline clock edge generator
-		WEN: in std_logic; -- EXT write enable
+		WEN : in std_logic; -- EXT write enable
 		TMM_WEN,
 		BAM_WEN,
 		FAM_WEN,
 		PAL_WEN,
-		AUX_WEN: out std_logic; -- write enable MUX
-		EN: in std_logic; -- EXT *ADDR enable (switch *AO to ADDR instead of *AI)
-		ADDR: in std_logic_vector(PPU_RAM_BUS_ADDR_WIDTH-1 downto 0); -- address in
-		TMM_AI: in std_logic_vector(PPU_TMM_ADDR_WIDTH-1 downto 0);
-		BAM_AI: in std_logic_vector(PPU_BAM_ADDR_WIDTH-1 downto 0);
-		FAM_AI: in std_logic_vector(PPU_FAM_ADDR_WIDTH-1 downto 0);
-		PAL_AI: in std_logic_vector(PPU_PAL_ADDR_WIDTH-1 downto 0);
-		AUX_AI: in std_logic_vector(PPU_AUX_ADDR_WIDTH-1 downto 0);
-		TMM_AO: out std_logic_vector(PPU_TMM_ADDR_WIDTH-1 downto 0);
-		BAM_AO: out std_logic_vector(PPU_BAM_ADDR_WIDTH-1 downto 0);
-		FAM_AO: out std_logic_vector(PPU_FAM_ADDR_WIDTH-1 downto 0);
-		PAL_AO: out std_logic_vector(PPU_PAL_ADDR_WIDTH-1 downto 0);
-		AUX_AO: out std_logic_vector(PPU_AUX_ADDR_WIDTH-1 downto 0));
+		AUX_WEN : out std_logic; -- write enable MUX
+		EN : in std_logic; -- EXT *ADDR enable (switch *AO to ADDR instead of *AI)
+		ADDR : in std_logic_vector(PPU_RAM_BUS_ADDR_WIDTH-1 downto 0); -- address in
+		TMM_AI : in std_logic_vector(PPU_TMM_ADDR_WIDTH-1 downto 0);
+		BAM_AI : in std_logic_vector(PPU_BAM_ADDR_WIDTH-1 downto 0);
+		FAM_AI : in std_logic_vector(PPU_FAM_ADDR_WIDTH-1 downto 0);
+		PAL_AI : in std_logic_vector(PPU_PAL_ADDR_WIDTH-1 downto 0);
+		AUX_AI : in std_logic_vector(PPU_AUX_ADDR_WIDTH-1 downto 0);
+		TMM_AO : out std_logic_vector(PPU_TMM_ADDR_WIDTH-1 downto 0);
+		BAM_AO : out std_logic_vector(PPU_BAM_ADDR_WIDTH-1 downto 0);
+		FAM_AO : out std_logic_vector(PPU_FAM_ADDR_WIDTH-1 downto 0);
+		PAL_AO : out std_logic_vector(PPU_PAL_ADDR_WIDTH-1 downto 0);
+		AUX_AO : out std_logic_vector(PPU_AUX_ADDR_WIDTH-1 downto 0));
 	end component;
 	component ppu_bam port( -- BAM block memory
-		clka: in std_logic;
-		rsta: in std_logic;
-		wea: in std_logic_vector(0 downto 0);
-		addra: in std_logic_vector(PPU_BAM_ADDR_WIDTH-1 downto 0);
-		dina: in std_logic_vector(PPU_BAM_DATA_WIDTH-1 downto 0);
-		douta: out std_logic_vector(PPU_BAM_DATA_WIDTH-1 downto 0);
-		rsta_busy: out std_logic);
+		clka : in std_logic;
+		rsta : in std_logic;
+		wea : in std_logic_vector(0 downto 0);
+		addra : in std_logic_vector(PPU_BAM_ADDR_WIDTH-1 downto 0);
+		dina : in std_logic_vector(PPU_BAM_DATA_WIDTH-1 downto 0);
+		douta : out std_logic_vector(PPU_BAM_DATA_WIDTH-1 downto 0);
+		rsta_busy : out std_logic);
 	end component;
 	component ppu_tmm port( -- TMM block memory
-		clka: in std_logic;
-		rsta: in std_logic;
-		wea: in std_logic_vector(0 downto 0);
-		addra: in std_logic_vector(PPU_TMM_ADDR_WIDTH-1 downto 0);
-		dina: in std_logic_vector(PPU_TMM_DATA_WIDTH-1 downto 0);
-		douta: out std_logic_vector(PPU_TMM_DATA_WIDTH-1 downto 0);
-		rsta_busy: out std_logic);
+		clka : in std_logic;
+		rsta : in std_logic;
+		wea : in std_logic_vector(0 downto 0);
+		addra : in std_logic_vector(PPU_TMM_ADDR_WIDTH-1 downto 0);
+		dina : in std_logic_vector(PPU_TMM_DATA_WIDTH-1 downto 0);
+		douta : out std_logic_vector(PPU_TMM_DATA_WIDTH-1 downto 0);
+		rsta_busy : out std_logic);
 	end component;
 	component ppu_aux port(
-		CLK: in std_logic; -- system clock
-		RESET: in std_logic; -- reset memory
+		CLK : in std_logic; -- system clock
+		RESET : in std_logic; -- reset memory
 
 		-- internal memory block (AUX)
-		AUX_WEN: in std_logic; -- VRAM AUX write enable
-		AUX_ADDR: in std_logic_vector(PPU_AUX_ADDR_WIDTH-1 downto 0); -- VRAM AUX address
-		AUX_DATA: in std_logic_vector(PPU_AUX_DATA_WIDTH-1 downto 0); -- VRAM AUX data
+		AUX_WEN : in std_logic; -- VRAM AUX write enable
+		AUX_ADDR : in std_logic_vector(PPU_AUX_ADDR_WIDTH-1 downto 0); -- VRAM AUX address
+		AUX_DATA : in std_logic_vector(PPU_AUX_DATA_WIDTH-1 downto 0); -- VRAM AUX data
 		
 		-- aux outputs
-		BG_SHIFT_X: out std_logic_vector(PPU_POS_H_WIDTH-1 downto 0);
-		BG_SHIFT_Y: out std_logic_vector(PPU_POS_V_WIDTH-1 downto 0);
-		FG_FETCH: out std_logic);
+		BG_SHIFT_X : out std_logic_vector(PPU_POS_H_WIDTH-1 downto 0);
+		BG_SHIFT_Y : out std_logic_vector(PPU_POS_V_WIDTH-1 downto 0);
+		FG_FETCH : out std_logic);
 	end component;
 	component ppu_sprite_bg port( -- background sprite
 		-- inputs
-		CLK: in std_logic; -- system clock
-		RESET: in std_logic; -- reset clock counter
-		OE: in std_logic; -- output enable (of CIDX)
-		X: in std_logic_vector(PPU_POS_H_WIDTH-1 downto 0); -- current screen pixel x
-		Y: in std_logic_vector(PPU_POS_V_WIDTH-1 downto 0); -- current screen pixel y
+		CLK : in std_logic; -- pipeline clock
+		RESET : in std_logic; -- reset clock counter
+		OE : in std_logic; -- output enable (of CIDX)
+		X : in std_logic_vector(PPU_POS_H_WIDTH-1 downto 0); -- current screen pixel x
+		Y : in std_logic_vector(PPU_POS_V_WIDTH-1 downto 0); -- current screen pixel y
 		
 		-- aux inputs
-		BG_SHIFT_X: in std_logic_vector(PPU_POS_H_WIDTH-1 downto 0);
-		BG_SHIFT_Y: in std_logic_vector(PPU_POS_V_WIDTH-1 downto 0);
+		BG_SHIFT_X : in std_logic_vector(PPU_POS_H_WIDTH-1 downto 0);
+		BG_SHIFT_Y : in std_logic_vector(PPU_POS_V_WIDTH-1 downto 0);
 
 		-- used memory blocks
-		BAM_ADDR: out std_logic_vector(PPU_BAM_ADDR_WIDTH-1 downto 0);
-		BAM_DATA: in std_logic_vector(PPU_BAM_DATA_WIDTH-1 downto 0);
-		TMM_ADDR: out std_logic_vector(PPU_TMM_ADDR_WIDTH-1 downto 0);
-		TMM_DATA: in std_logic_vector(PPU_TMM_DATA_WIDTH-1 downto 0);
+		BAM_ADDR : out std_logic_vector(PPU_BAM_ADDR_WIDTH-1 downto 0);
+		BAM_DATA : in std_logic_vector(PPU_BAM_DATA_WIDTH-1 downto 0);
+		TMM_ADDR : out std_logic_vector(PPU_TMM_ADDR_WIDTH-1 downto 0);
+		TMM_DATA : in std_logic_vector(PPU_TMM_DATA_WIDTH-1 downto 0);
 
 		-- outputs
-		CIDX: out std_logic_vector(PPU_PALETTE_CIDX_WIDTH-1 downto 0)); -- output color
+		CIDX : out std_logic_vector(PPU_PALETTE_CIDX_WIDTH-1 downto 0)); -- output color
 	end component;
-	component ppu_sprite_fg port( -- foreground sprite
-		-- inputs
-		CLK: in std_logic; -- system clock
-		RESET: in std_logic; -- reset internal memory and clock counters
-		OE: in std_logic; -- output enable (of CIDX)
-		X: in std_logic_vector(PPU_POS_H_WIDTH-1 downto 0); -- current screen pixel x
-		Y: in std_logic_vector(PPU_POS_V_WIDTH-1 downto 0); -- current screen pixel y
-		FETCH: in std_logic; -- fetch sprite data from TMM (TODO: generic map, set foreground sprite component index)
+	component ppu_sprite_fg -- foreground sprite
+		generic (
+			IDX : natural := 0);
+		port(
+			-- inputs
+			CLK : in std_logic; -- system clock
+			RESET : in std_logic; -- reset internal memory and clock counters
+			OE : in std_logic; -- output enable (of CIDX)
+			X : in std_logic_vector(PPU_POS_H_WIDTH-1 downto 0); -- current screen pixel x
+			Y : in std_logic_vector(PPU_POS_V_WIDTH-1 downto 0); -- current screen pixel y
+			FETCH : in std_logic; -- fetch sprite data from TMM
+			VBLANK : in std_logic; -- fetch during vblank
 
-		-- internal memory block (FAM)
-		FAM_WEN: in std_logic; -- VRAM FAM write enable
-		FAM_ADDR: in std_logic_vector(PPU_FAM_ADDR_WIDTH-1 downto 0); -- VRAM fam address
-		FAM_DATA: in std_logic_vector(PPU_FAM_DATA_WIDTH-1 downto 0); -- VRAM fam data
+			-- internal memory block (FAM)
+			FAM_WEN : in std_logic; -- VRAM FAM write enable
+			FAM_ADDR : in std_logic_vector(PPU_FAM_ADDR_WIDTH-1 downto 0); -- VRAM fam address
+			FAM_DATA : in std_logic_vector(PPU_FAM_DATA_WIDTH-1 downto 0); -- VRAM fam data
 
-		-- used memory blocks
-		TMM_ADDR: out std_logic_vector(PPU_TMM_ADDR_WIDTH-1 downto 0);
-		TMM_DATA: in std_logic_vector(PPU_TMM_DATA_WIDTH-1 downto 0);
+			-- used memory blocks
+			TMM_ADDR : out std_logic_vector(PPU_TMM_ADDR_WIDTH-1 downto 0);
+			TMM_DATA : in std_logic_vector(PPU_TMM_DATA_WIDTH-1 downto 0);
 
-		-- outputs
-		CIDX: out std_logic_vector(PPU_PALETTE_CIDX_WIDTH-1 downto 0); -- output color
-		HIT: out std_logic); -- current pixel is not transparent
+			-- outputs
+			CIDX : out std_logic_vector(PPU_PALETTE_CIDX_WIDTH-1 downto 0); -- output color
+			HIT : out std_logic); -- current pixel is not transparent
 	end component;
 	component ppu_comp port( -- compositor
-		FG_HIT: in std_logic_vector(PPU_FG_SPRITE_COUNT-1 downto 0);
-		BG_EN: out std_logic;
-		FG_EN: out std_logic_vector(PPU_FG_SPRITE_COUNT-1 downto 0));
+		FG_HIT : in std_logic_vector(PPU_FG_SPRITE_COUNT-1 downto 0);
+		BG_EN : out std_logic;
+		FG_EN : out std_logic_vector(PPU_FG_SPRITE_COUNT-1 downto 0));
 	end component;
 	component ppu_plut port( -- palette lookup table
-		CLK: in std_logic; -- system clock
-		CIDX: in std_logic_vector(PPU_PALETTE_CIDX_WIDTH-1 downto 0); -- color in
-		RESET: in std_logic;
+		CLK : in std_logic; -- system clock
+		CIDX : in std_logic_vector(PPU_PALETTE_CIDX_WIDTH-1 downto 0); -- color in
+		RESET : in std_logic;
 
 		-- internal memory block (AUX)
-		PAL_WEN: in std_logic; -- VRAM PAL write enable
-		PAL_ADDR: in std_logic_vector(PPU_PAL_ADDR_WIDTH-1 downto 0); -- VRAM PAL address
-		PAL_DATA: in std_logic_vector(PPU_PAL_DATA_WIDTH-1 downto 0); -- VRAM PAL data
+		PAL_WEN : in std_logic; -- VRAM PAL write enable
+		PAL_ADDR : in std_logic_vector(PPU_PAL_ADDR_WIDTH-1 downto 0); -- VRAM PAL address
+		PAL_DATA : in std_logic_vector(PPU_PAL_DATA_WIDTH-1 downto 0); -- VRAM PAL data
 		
-		R,G,B: out std_logic_vector(PPU_COLOR_OUTPUT_DEPTH-1 downto 0)); -- VGA color out
+		R,G,B : out std_logic_vector(PPU_COLOR_OUTPUT_DEPTH-1 downto 0)); -- VGA color out
 	end component;
 	component ppu_vga_tiny port( -- tiny vga signal generator
-		CLK: in std_logic; -- system clock
-		RESET: in std_logic;
+		CLK : in std_logic; -- system clock
+		RESET : in std_logic;
 
-		X: out std_logic_vector(PPU_POS_H_WIDTH-1 downto 0); -- current screen pixel x
-		Y: out std_logic_vector(PPU_POS_V_WIDTH-1 downto 0); -- current screen pixel y
+		X : out std_logic_vector(PPU_POS_H_WIDTH-1 downto 0); -- current screen pixel x
+		Y : out std_logic_vector(PPU_POS_V_WIDTH-1 downto 0); -- current screen pixel y
 		
 		VSYNC, VBLANK,
-		HSYNC, HBLANK: out std_logic); -- VGA sync outputs
+		HSYNC, HBLANK : out std_logic); -- VGA sync outputs
 	end component;
 	component ppu_vga_native port( -- native vga signal generator (upscaler)
-		CLK: in std_logic; -- system clock
-		RESET: in std_logic;
+		CLK : in std_logic; -- system clock
+		RESET : in std_logic;
 
-		X: in std_logic_vector(PPU_POS_H_WIDTH-1 downto 0); -- current screen pixel x
-		Y: in std_logic_vector(PPU_POS_V_WIDTH-1 downto 0); -- current screen pixel y
-		PREADY: in std_logic; -- current pixel ready (pixel color is stable)
-		RI,GI,BI: in std_logic_vector(PPU_COLOR_OUTPUT_DEPTH-1 downto 0); -- VGA color in
+		X : in std_logic_vector(PPU_POS_H_WIDTH-1 downto 0); -- current screen pixel x
+		Y : in std_logic_vector(PPU_POS_V_WIDTH-1 downto 0); -- current screen pixel y
+		PREADY : in std_logic; -- current pixel ready (pixel color is stable)
+		RI,GI,BI : in std_logic_vector(PPU_COLOR_OUTPUT_DEPTH-1 downto 0); -- VGA color in
 		
-		RO,GO,BO: out std_logic_vector(PPU_COLOR_OUTPUT_DEPTH-1 downto 0); -- VGA color out
-		VSYNC, HSYNC: out std_logic); -- VGA sync outputs
+		RO,GO,BO : out std_logic_vector(PPU_COLOR_OUTPUT_DEPTH-1 downto 0); -- VGA color out
+		VSYNC, HSYNC : out std_logic); -- VGA sync outputs
 	end component;
 
 	-- signals
-	signal SYSCLK, SYSRST: std_logic; -- system clock and reset
-	signal PL_SPRITE, PL_COMP_PAL, PL_DONE: std_logic; -- pipeline stages
-	signal TMM_WEN, BAM_WEN, FAM_WEN, PAL_WEN, AUX_WEN: std_logic;
-	signal TMM_AI, TMM_AO: std_logic_vector(PPU_TMM_ADDR_WIDTH-1 downto 0);
-	signal BAM_AI, BAM_AO: std_logic_vector(PPU_BAM_ADDR_WIDTH-1 downto 0);
-	signal FAM_AI, FAM_AO: std_logic_vector(PPU_FAM_ADDR_WIDTH-1 downto 0);
-	signal PAL_AI, PAL_AO: std_logic_vector(PPU_PAL_ADDR_WIDTH-1 downto 0);
-	signal AUX_AI, AUX_AO: std_logic_vector(PPU_AUX_ADDR_WIDTH-1 downto 0);
-	signal TMM_DO: std_logic_vector(PPU_TMM_DATA_WIDTH-1 downto 0);
-	signal BAM_DO: std_logic_vector(PPU_BAM_DATA_WIDTH-1 downto 0);
-	signal FAM_DO: std_logic_vector(PPU_FAM_DATA_WIDTH-1 downto 0);
-	signal PAL_DO: std_logic_vector(PPU_PAL_DATA_WIDTH-1 downto 0);
-	signal AUX_DO: std_logic_vector(PPU_AUX_DATA_WIDTH-1 downto 0);
-	signal CIDX: std_logic_vector(PPU_PALETTE_CIDX_WIDTH-1 downto 0);
-	signal BG_EN: std_logic;
-	signal FG_EN, FG_HIT: std_logic_vector(PPU_FG_SPRITE_COUNT-1 downto 0);
-	signal X: std_logic_vector(PPU_POS_H_WIDTH-1 downto 0); -- current screen pixel x
-	signal Y: std_logic_vector(PPU_POS_V_WIDTH-1 downto 0); -- current screen pixel y
-	signal UR,UG,UB: std_logic_vector(PPU_COLOR_OUTPUT_DEPTH-1 downto 0); -- unstable RGB (to be buffered)
-	signal SR,SG,SB: std_logic_vector(PPU_COLOR_OUTPUT_DEPTH-1 downto 0); -- stable RGB (buffered until PL_COMP_PAL)
-	signal BG_SHIFT_X: std_logic_vector(PPU_POS_H_WIDTH-1 downto 0);
-	signal BG_SHIFT_Y: std_logic_vector(PPU_POS_V_WIDTH-1 downto 0);
-	signal FG_FETCH: std_logic;
+	signal SYSCLK, SYSRST : std_logic; -- system clock and reset
+	signal PL_SPRITE, PL_COMP_PAL, PL_DONE : std_logic; -- pipeline stages
+	signal TMM_WEN, BAM_WEN, FAM_WEN, PAL_WEN, AUX_WEN : std_logic;
+	signal TMM_AI, TMM_AO : std_logic_vector(PPU_TMM_ADDR_WIDTH-1 downto 0);
+	signal BAM_AI, BAM_AO : std_logic_vector(PPU_BAM_ADDR_WIDTH-1 downto 0);
+	signal FAM_AI, FAM_AO : std_logic_vector(PPU_FAM_ADDR_WIDTH-1 downto 0);
+	signal PAL_AI, PAL_AO : std_logic_vector(PPU_PAL_ADDR_WIDTH-1 downto 0);
+	signal AUX_AI, AUX_AO : std_logic_vector(PPU_AUX_ADDR_WIDTH-1 downto 0);
+	signal TMM_DO : std_logic_vector(PPU_TMM_DATA_WIDTH-1 downto 0);
+	signal BAM_DO : std_logic_vector(PPU_BAM_DATA_WIDTH-1 downto 0);
+	signal FAM_DO : std_logic_vector(PPU_FAM_DATA_WIDTH-1 downto 0);
+	signal PAL_DO : std_logic_vector(PPU_PAL_DATA_WIDTH-1 downto 0);
+	signal AUX_DO : std_logic_vector(PPU_AUX_DATA_WIDTH-1 downto 0);
+	signal CIDX : std_logic_vector(PPU_PALETTE_CIDX_WIDTH-1 downto 0);
+	signal BG_EN : std_logic;
+	signal FG_EN, FG_HIT : std_logic_vector(PPU_FG_SPRITE_COUNT-1 downto 0);
+	signal X : std_logic_vector(PPU_POS_H_WIDTH-1 downto 0); -- current screen pixel x
+	signal Y : std_logic_vector(PPU_POS_V_WIDTH-1 downto 0); -- current screen pixel y
+	signal UR,UG,UB : std_logic_vector(PPU_COLOR_OUTPUT_DEPTH-1 downto 0); -- unstable RGB (to be buffered)
+	signal SR,SG,SB : std_logic_vector(PPU_COLOR_OUTPUT_DEPTH-1 downto 0); -- stable RGB (buffered until PL_COMP_PAL)
+	signal BG_SHIFT_X : std_logic_vector(PPU_POS_H_WIDTH-1 downto 0);
+	signal BG_SHIFT_Y : std_logic_vector(PPU_POS_V_WIDTH-1 downto 0);
+	signal FG_FETCH : std_logic;
+	signal TINY_VBLANK, TINY_VSYNC, TINY_HBLANK, TINY_HSYNC,
+	       NATIVE_VSYNC, NATIVE_HSYNC : std_logic;
 begin
 	SYSCLK <= CLK100;
 	SYSRST <= RESET;
@@ -197,14 +204,21 @@ begin
 	FAM_AI <= (others => '0');
 	PAL_AI <= (others => '0');
 
-	pipeline_clock_edge_generator: component ppu_pceg port map(
+	TVBLANK <= TINY_VBLANK;
+	TVSYNC <= TINY_VSYNC;
+	THBLANK <= TINY_HBLANK;
+	THSYNC <= TINY_HSYNC;
+	NVSYNC <= NATIVE_VSYNC;
+	NHSYNC <= NATIVE_HSYNC;
+
+	pipeline_clock_edge_generator : component ppu_pceg port map(
 		CLK => SYSCLK,
 		RESET => SYSRST,
 		SPRITE => PL_SPRITE,
 		COMP_PAL => PL_COMP_PAL,
 		DONE => PL_DONE);
 
-	address_decoder: component ppu_addr_dec port map(
+	address_decoder : component ppu_addr_dec port map(
 		EN => EN,
 		WEN => WEN,
 		ADDR => ADDR,
@@ -224,7 +238,7 @@ begin
 		PAL_WEN => PAL_WEN,
 		AUX_WEN => AUX_WEN);
 
-	background_attribute_memory: component ppu_bam port map(
+	background_attribute_memory : component ppu_bam port map(
 		clka => SYSCLK,
 		rsta => SYSRST,
 		wea => (others => BAM_WEN),
@@ -232,7 +246,7 @@ begin
 		dina => DATA(PPU_BAM_DATA_WIDTH-1 downto 0),
 		douta => BAM_DO,
 		rsta_busy => open);
-	tilemap_memory: component ppu_tmm port map(
+	tilemap_memory : component ppu_tmm port map(
 		clka => SYSCLK,
 		rsta => SYSRST,
 		wea => (others => TMM_WEN),
@@ -241,7 +255,7 @@ begin
 		douta => TMM_DO,
 		rsta_busy => open);
 
-	aux: component ppu_aux port map(
+	aux : component ppu_aux port map(
 		CLK => SYSCLK,
 		RESET => SYSRST,
 		AUX_WEN => AUX_WEN,
@@ -251,7 +265,7 @@ begin
 		BG_SHIFT_Y => BG_SHIFT_Y,
 		FG_FETCH => FG_FETCH);
 
-	background_sprite: component ppu_sprite_bg port map(
+	background_sprite : component ppu_sprite_bg port map(
 		CLK => PL_SPRITE,
 		RESET => SYSRST,
 		OE => BG_EN,
@@ -265,29 +279,32 @@ begin
 		TMM_DATA => TMM_DO,
 		CIDX => CIDX);
 
-	foreground_sprites: for FG_IDX in 0 to PPU_FG_SPRITE_COUNT-1 generate
-		foreground_sprite: component ppu_sprite_fg port map(
-			CLK => PL_SPRITE,
-			RESET => SYSRST,
-			OE => FG_EN(FG_IDX),
-			X => X,
-			Y => Y,
-			FETCH => FG_FETCH,
-			FAM_WEN => FAM_WEN,
-			FAM_ADDR => FAM_AO,
-			FAM_DATA => DATA(PPU_FAM_DATA_WIDTH-1 downto 0),
-			TMM_ADDR => TMM_AI,
-			TMM_DATA => TMM_DO,
-			CIDX => CIDX,
-			HIT => FG_HIT(FG_IDX));
+	foreground_sprites : for FG_IDX in 0 to PPU_FG_SPRITE_COUNT-1 generate
+		foreground_sprite : component ppu_sprite_fg
+			generic map( IDX => FG_IDX )
+			port map(
+				CLK => SYSCLK,
+				RESET => SYSRST,
+				OE => FG_EN(FG_IDX),
+				X => X,
+				Y => Y,
+				FETCH => FG_FETCH,
+				VBLANK => TINY_VBLANK,
+				FAM_WEN => FAM_WEN,
+				FAM_ADDR => FAM_AO,
+				FAM_DATA => DATA(PPU_FAM_DATA_WIDTH-1 downto 0),
+				TMM_ADDR => TMM_AI,
+				TMM_DATA => TMM_DO,
+				CIDX => CIDX,
+				HIT => FG_HIT(FG_IDX));
 	end generate;
 
-	compositor: component ppu_comp port map( -- compositor
+	compositor : component ppu_comp port map( -- compositor
 		FG_HIT => FG_HIT,
 		BG_EN => BG_EN,
 		FG_EN => FG_EN);
 
-	palette_lookup: component ppu_plut port map( -- palette lookup table
+	palette_lookup : component ppu_plut port map( -- palette lookup table
 		CLK => SYSCLK,
 		CIDX => CIDX,
 		RESET => SYSRST,
@@ -312,17 +329,17 @@ begin
 		end if;
 	end process;
 
-	tiny_vga_signal_generator: component ppu_vga_tiny port map( -- tiny vga signal generator
+	tiny_vga_signal_generator : component ppu_vga_tiny port map( -- tiny vga signal generator
 		CLK => SYSCLK,
 		RESET => SYSRST,
 		X => X,
 		Y => Y,
-		VSYNC => TVSYNC,
-		VBLANK => TVBLANK,
-		HSYNC => THSYNC,
-		HBLANK => THBLANK);
+		VSYNC => TINY_VSYNC,
+		VBLANK => TINY_VBLANK,
+		HSYNC => TINY_HSYNC,
+		HBLANK => TINY_HBLANK);
 
-	native_vga_signal_generator: component ppu_vga_native port map( -- native vga signal generator (upscaler)
+	native_vga_signal_generator : component ppu_vga_native port map( -- native vga signal generator (upscaler)
 		CLK => SYSCLK,
 		RESET => SYSRST,
 		X => X,
@@ -334,6 +351,6 @@ begin
 		RO => R,
 		GO => G,
 		BO => B,
-		VSYNC => NVSYNC,
-		HSYNC => NHSYNC);
+		VSYNC => NATIVE_VSYNC,
+		HSYNC => NATIVE_HSYNC);
 end Behavioral;
diff --git a/basys3/basys3.srcs/ppu_addr_dec.vhd b/basys3/basys3.srcs/ppu_addr_dec.vhd
new file mode 100644
index 0000000..e0c374f
--- /dev/null
+++ b/basys3/basys3.srcs/ppu_addr_dec.vhd
@@ -0,0 +1,51 @@
+library ieee;
+library work;
+use ieee.std_logic_1164.all;
+--use ieee.numeric_std.all;
+use work.ppu_consts.all;
+
+entity ppu_addr_dec is port(
+	EN : in std_logic; -- EXT *ADDR enable (switch *AO to ADDR instead of *AI)
+	WEN : in std_logic; -- EXT write enable
+	TMM_WEN,
+	BAM_WEN,
+	FAM_WEN,
+	PAL_WEN,
+	AUX_WEN : out std_logic; -- write enable MUX
+	ADDR : in std_logic_vector(PPU_RAM_BUS_ADDR_WIDTH-1 downto 0); -- address in
+	TMM_AI : in std_logic_vector(PPU_TMM_ADDR_WIDTH-1 downto 0);
+	BAM_AI : in std_logic_vector(PPU_BAM_ADDR_WIDTH-1 downto 0);
+	FAM_AI : in std_logic_vector(PPU_FAM_ADDR_WIDTH-1 downto 0);
+	PAL_AI : in std_logic_vector(PPU_PAL_ADDR_WIDTH-1 downto 0);
+	AUX_AI : in std_logic_vector(PPU_AUX_ADDR_WIDTH-1 downto 0);
+	TMM_AO : out std_logic_vector(PPU_TMM_ADDR_WIDTH-1 downto 0);
+	BAM_AO : out std_logic_vector(PPU_BAM_ADDR_WIDTH-1 downto 0);
+	FAM_AO : out std_logic_vector(PPU_FAM_ADDR_WIDTH-1 downto 0);
+	PAL_AO : out std_logic_vector(PPU_PAL_ADDR_WIDTH-1 downto 0);
+	AUX_AO : out std_logic_vector(PPU_AUX_ADDR_WIDTH-1 downto 0));
+end ppu_addr_dec;
+
+architecture Behavioral of ppu_addr_dec is
+	signal TMM_RANGE, BAM_RANGE, FAM_RANGE, PAL_RANGE, AUX_RANGE : std_logic := '0'; -- ADDR in range of memory area
+begin
+	-- address MUX
+	TMM_AO <= ADDR(PPU_TMM_ADDR_WIDTH-1 downto 0) when EN = '1' else TMM_AI;
+	BAM_AO <= ADDR(PPU_BAM_ADDR_WIDTH-1 downto 0) when EN = '1' else BAM_AI;
+	FAM_AO <= ADDR(PPU_FAM_ADDR_WIDTH-1 downto 0) when EN = '1' else FAM_AI;
+	PAL_AO <= ADDR(PPU_PAL_ADDR_WIDTH-1 downto 0) when EN = '1' else PAL_AI;
+	AUX_AO <= ADDR(PPU_AUX_ADDR_WIDTH-1 downto 0) when EN = '1' else AUX_AI;
+
+	-- WEN MUX
+	TMM_WEN <= TMM_RANGE and WEN;
+	BAM_WEN <= BAM_RANGE and WEN;
+	FAM_WEN <= FAM_RANGE and WEN;
+	PAL_WEN <= PAL_RANGE and WEN;
+	AUX_WEN <= AUX_RANGE and WEN;
+
+	-- address ranges
+	TMM_RANGE <= '1' when not ((ADDR(15) and ADDR(14) and ADDR(13)) or (ADDR(15) and ADDR(14) and ADDR(12))) else '0';
+	BAM_RANGE <= '1' when TMM_RANGE = '0' and (ADDR(11) = '0') else '0';
+	FAM_RANGE <= '1' when TMM_RANGE = '0' and (ADDR(11) = '1' and ADDR(10) = '0') else '0';
+	PAL_RANGE <= '1' when TMM_RANGE = '0' and (ADDR(11) = '1' and ADDR(10) = '1' and ADDR(9) = '0') else '0';
+	AUX_RANGE <= '1' when TMM_RANGE = '0' and (ADDR(11) = '1' and ADDR(10) = '1' and ADDR(9) = '1') else '0';
+end Behavioral;
diff --git a/basys3/basys3.srcs/ppu_addr_dec.vhdl b/basys3/basys3.srcs/ppu_addr_dec.vhdl
deleted file mode 100644
index 28c22fc..0000000
--- a/basys3/basys3.srcs/ppu_addr_dec.vhdl
+++ /dev/null
@@ -1,51 +0,0 @@
-library ieee;
-library work;
-use ieee.std_logic_1164.all;
---use ieee.numeric_std.all;
-use work.ppu_consts.all;
-
-entity ppu_addr_dec is port(
-	EN: in std_logic; -- EXT *ADDR enable (switch *AO to ADDR instead of *AI)
-	WEN: in std_logic; -- EXT write enable
-	TMM_WEN,
-	BAM_WEN,
-	FAM_WEN,
-	PAL_WEN,
-	AUX_WEN: out std_logic; -- write enable MUX
-	ADDR: in std_logic_vector(PPU_RAM_BUS_ADDR_WIDTH-1 downto 0); -- address in
-	TMM_AI: in std_logic_vector(PPU_TMM_ADDR_WIDTH-1 downto 0);
-	BAM_AI: in std_logic_vector(PPU_BAM_ADDR_WIDTH-1 downto 0);
-	FAM_AI: in std_logic_vector(PPU_FAM_ADDR_WIDTH-1 downto 0);
-	PAL_AI: in std_logic_vector(PPU_PAL_ADDR_WIDTH-1 downto 0);
-	AUX_AI: in std_logic_vector(PPU_AUX_ADDR_WIDTH-1 downto 0);
-	TMM_AO: out std_logic_vector(PPU_TMM_ADDR_WIDTH-1 downto 0);
-	BAM_AO: out std_logic_vector(PPU_BAM_ADDR_WIDTH-1 downto 0);
-	FAM_AO: out std_logic_vector(PPU_FAM_ADDR_WIDTH-1 downto 0);
-	PAL_AO: out std_logic_vector(PPU_PAL_ADDR_WIDTH-1 downto 0);
-	AUX_AO: out std_logic_vector(PPU_AUX_ADDR_WIDTH-1 downto 0));
-end ppu_addr_dec;
-
-architecture Behavioral of ppu_addr_dec is
-	signal TMM_RANGE, BAM_RANGE, FAM_RANGE, PAL_RANGE, AUX_RANGE: std_logic := '0'; -- ADDR in range of memory area
-begin
-	-- address MUX
-	TMM_AO <= ADDR(PPU_TMM_ADDR_WIDTH-1 downto 0) when EN = '1' else TMM_AI;
-	BAM_AO <= ADDR(PPU_BAM_ADDR_WIDTH-1 downto 0) when EN = '1' else BAM_AI;
-	FAM_AO <= ADDR(PPU_FAM_ADDR_WIDTH-1 downto 0) when EN = '1' else FAM_AI;
-	PAL_AO <= ADDR(PPU_PAL_ADDR_WIDTH-1 downto 0) when EN = '1' else PAL_AI;
-	AUX_AO <= ADDR(PPU_AUX_ADDR_WIDTH-1 downto 0) when EN = '1' else AUX_AI;
-
-	-- WEN MUX
-	TMM_WEN <= TMM_RANGE and WEN;
-	BAM_WEN <= BAM_RANGE and WEN;
-	FAM_WEN <= FAM_RANGE and WEN;
-	PAL_WEN <= PAL_RANGE and WEN;
-	AUX_WEN <= AUX_RANGE and WEN;
-
-	-- address ranges
-	TMM_RANGE <= '1' when not (ADDR(15) = '1' and ADDR(14) = '1') else '0';
-	BAM_RANGE <= '1' when (ADDR(15) = '1' and ADDR(14) = '1') and (ADDR(11) = '0') else '0';
-	FAM_RANGE <= '1' when (ADDR(15) = '1' and ADDR(14) = '1') and (ADDR(11) = '1' and ADDR(10) = '0') else '0';
-	PAL_RANGE <= '1' when (ADDR(15) = '1' and ADDR(14) = '1') and (ADDR(11) = '1' and ADDR(10) = '1' and ADDR(9) = '0') else '0';
-	AUX_RANGE <= '1' when (ADDR(15) = '1' and ADDR(14) = '1') and (ADDR(11) = '1' and ADDR(10) = '1' and ADDR(9) = '1') else '0';
-end Behavioral;
diff --git a/basys3/basys3.srcs/ppu_addr_dec_tb.vhd b/basys3/basys3.srcs/ppu_addr_dec_tb.vhd
new file mode 100644
index 0000000..f31ee67
--- /dev/null
+++ b/basys3/basys3.srcs/ppu_addr_dec_tb.vhd
@@ -0,0 +1,86 @@
+library ieee;
+library unisim;
+library work;
+
+use ieee.std_logic_1164.all;
+use ieee.numeric_std.all;
+use unisim.vcomponents.all;
+use work.ppu_consts.all;
+
+entity ppu_addr_dec_tb is
+end ppu_addr_dec_tb;
+
+architecture behavioral of ppu_addr_dec_tb is
+	component ppu_addr_dec port(
+		EN : in std_logic; -- EXT *ADDR enable (switch *AO to ADDR instead of *AI)
+		WEN : in std_logic; -- EXT write enable
+		TMM_WEN,
+		BAM_WEN,
+		FAM_WEN,
+		PAL_WEN,
+		AUX_WEN : out std_logic; -- write enable MUX
+		ADDR : in std_logic_vector(PPU_RAM_BUS_ADDR_WIDTH-1 downto 0); -- address in
+		TMM_AI : in std_logic_vector(PPU_TMM_ADDR_WIDTH-1 downto 0);
+		BAM_AI : in std_logic_vector(PPU_BAM_ADDR_WIDTH-1 downto 0);
+		FAM_AI : in std_logic_vector(PPU_FAM_ADDR_WIDTH-1 downto 0);
+		PAL_AI : in std_logic_vector(PPU_PAL_ADDR_WIDTH-1 downto 0);
+		AUX_AI : in std_logic_vector(PPU_AUX_ADDR_WIDTH-1 downto 0);
+		TMM_AO : out std_logic_vector(PPU_TMM_ADDR_WIDTH-1 downto 0);
+		BAM_AO : out std_logic_vector(PPU_BAM_ADDR_WIDTH-1 downto 0);
+		FAM_AO : out std_logic_vector(PPU_FAM_ADDR_WIDTH-1 downto 0);
+		PAL_AO : out std_logic_vector(PPU_PAL_ADDR_WIDTH-1 downto 0);
+		AUX_AO : out std_logic_vector(PPU_AUX_ADDR_WIDTH-1 downto 0));
+	end component;
+	signal EN : std_logic;
+	signal WEN : std_logic;
+	signal TMM_WEN, BAM_WEN, FAM_WEN, PAL_WEN, AUX_WEN : std_logic;
+	signal ADDR : std_logic_vector(PPU_RAM_BUS_ADDR_WIDTH-1 downto 0);
+	signal TMM_AI : std_logic_vector(PPU_TMM_ADDR_WIDTH-1 downto 0);
+	signal BAM_AI : std_logic_vector(PPU_BAM_ADDR_WIDTH-1 downto 0);
+	signal FAM_AI : std_logic_vector(PPU_FAM_ADDR_WIDTH-1 downto 0);
+	signal PAL_AI : std_logic_vector(PPU_PAL_ADDR_WIDTH-1 downto 0);
+	signal AUX_AI : std_logic_vector(PPU_AUX_ADDR_WIDTH-1 downto 0);
+	signal TMM_AO : std_logic_vector(PPU_TMM_ADDR_WIDTH-1 downto 0);
+	signal BAM_AO : std_logic_vector(PPU_BAM_ADDR_WIDTH-1 downto 0);
+	signal FAM_AO : std_logic_vector(PPU_FAM_ADDR_WIDTH-1 downto 0);
+	signal PAL_AO : std_logic_vector(PPU_PAL_ADDR_WIDTH-1 downto 0);
+	signal AUX_AO : std_logic_vector(PPU_AUX_ADDR_WIDTH-1 downto 0);
+begin
+	uut : ppu_addr_dec port map(
+    EN => EN,
+    WEN => WEN,
+    TMM_WEN => TMM_WEN,
+    BAM_WEN => BAM_WEN,
+    FAM_WEN => FAM_WEN,
+    PAL_WEN => PAL_WEN,
+    AUX_WEN => AUX_WEN,
+    ADDR => ADDR,
+    TMM_AI => TMM_AI,
+    BAM_AI => BAM_AI,
+    FAM_AI => FAM_AI,
+    PAL_AI => PAL_AI,
+    AUX_AI => AUX_AI,
+    TMM_AO => TMM_AO,
+    BAM_AO => BAM_AO,
+    FAM_AO => FAM_AO,
+    PAL_AO => PAL_AO,
+    AUX_AO => AUX_AO);
+
+  EN <= '1';
+  WEN <= '1';
+
+  TMM_AI <= (others => '1');
+  BAM_AI <= (others => '0');
+  FAM_AI <= (others => '1');
+  PAL_AI <= (others => '0');
+  AUX_AI <= (others => '0');
+
+	tb : process
+	begin
+		for i in 0 to 65535 loop
+      ADDR <= std_logic_vector(to_unsigned(i,16));
+      wait for 10 ps;
+		end loop;
+		wait; -- stop for simulator
+	end process;
+end;
diff --git a/basys3/basys3.srcs/ppu_addr_dec_tb.vhdl b/basys3/basys3.srcs/ppu_addr_dec_tb.vhdl
deleted file mode 100644
index 5c7119d..0000000
--- a/basys3/basys3.srcs/ppu_addr_dec_tb.vhdl
+++ /dev/null
@@ -1,86 +0,0 @@
-library ieee;
-library unisim;
-library work;
-
-use ieee.std_logic_1164.all;
-use ieee.numeric_std.all;
-use unisim.vcomponents.all;
-use work.ppu_consts.all;
-
-entity ppu_addr_dec_tb is
-end ppu_addr_dec_tb;
-
-architecture behavioral of ppu_addr_dec_tb is
-	component ppu_addr_dec port(
-		EN: in std_logic; -- EXT *ADDR enable (switch *AO to ADDR instead of *AI)
-		WEN: in std_logic; -- EXT write enable
-		TMM_WEN,
-		BAM_WEN,
-		FAM_WEN,
-		PAL_WEN,
-		AUX_WEN: out std_logic; -- write enable MUX
-		ADDR: in std_logic_vector(PPU_RAM_BUS_ADDR_WIDTH-1 downto 0); -- address in
-		TMM_AI: in std_logic_vector(PPU_TMM_ADDR_WIDTH-1 downto 0);
-		BAM_AI: in std_logic_vector(PPU_BAM_ADDR_WIDTH-1 downto 0);
-		FAM_AI: in std_logic_vector(PPU_FAM_ADDR_WIDTH-1 downto 0);
-		PAL_AI: in std_logic_vector(PPU_PAL_ADDR_WIDTH-1 downto 0);
-		AUX_AI: in std_logic_vector(PPU_AUX_ADDR_WIDTH-1 downto 0);
-		TMM_AO: out std_logic_vector(PPU_TMM_ADDR_WIDTH-1 downto 0);
-		BAM_AO: out std_logic_vector(PPU_BAM_ADDR_WIDTH-1 downto 0);
-		FAM_AO: out std_logic_vector(PPU_FAM_ADDR_WIDTH-1 downto 0);
-		PAL_AO: out std_logic_vector(PPU_PAL_ADDR_WIDTH-1 downto 0);
-		AUX_AO: out std_logic_vector(PPU_AUX_ADDR_WIDTH-1 downto 0));
-	end component;
-	signal EN: std_logic;
-	signal WEN: std_logic;
-	signal TMM_WEN, BAM_WEN, FAM_WEN, PAL_WEN, AUX_WEN: std_logic;
-	signal ADDR: std_logic_vector(PPU_RAM_BUS_ADDR_WIDTH-1 downto 0);
-	signal TMM_AI: std_logic_vector(PPU_TMM_ADDR_WIDTH-1 downto 0);
-	signal BAM_AI: std_logic_vector(PPU_BAM_ADDR_WIDTH-1 downto 0);
-	signal FAM_AI: std_logic_vector(PPU_FAM_ADDR_WIDTH-1 downto 0);
-	signal PAL_AI: std_logic_vector(PPU_PAL_ADDR_WIDTH-1 downto 0);
-	signal AUX_AI: std_logic_vector(PPU_AUX_ADDR_WIDTH-1 downto 0);
-	signal TMM_AO: std_logic_vector(PPU_TMM_ADDR_WIDTH-1 downto 0);
-	signal BAM_AO: std_logic_vector(PPU_BAM_ADDR_WIDTH-1 downto 0);
-	signal FAM_AO: std_logic_vector(PPU_FAM_ADDR_WIDTH-1 downto 0);
-	signal PAL_AO: std_logic_vector(PPU_PAL_ADDR_WIDTH-1 downto 0);
-	signal AUX_AO: std_logic_vector(PPU_AUX_ADDR_WIDTH-1 downto 0);
-begin
-	uut: ppu_addr_dec port map(
-    EN => EN,
-    WEN => WEN,
-    TMM_WEN => TMM_WEN,
-    BAM_WEN => BAM_WEN,
-    FAM_WEN => FAM_WEN,
-    PAL_WEN => PAL_WEN,
-    AUX_WEN => AUX_WEN,
-    ADDR => ADDR,
-    TMM_AI => TMM_AI,
-    BAM_AI => BAM_AI,
-    FAM_AI => FAM_AI,
-    PAL_AI => PAL_AI,
-    AUX_AI => AUX_AI,
-    TMM_AO => TMM_AO,
-    BAM_AO => BAM_AO,
-    FAM_AO => FAM_AO,
-    PAL_AO => PAL_AO,
-    AUX_AO => AUX_AO);
-
-  EN <= '1';
-  WEN <= '1';
-
-  TMM_AI <= (others => '1');
-  BAM_AI <= (others => '0');
-  FAM_AI <= (others => '1');
-  PAL_AI <= (others => '0');
-  AUX_AI <= (others => '0');
-
-	tb: process
-	begin
-		for i in 0 to 65535 loop
-      ADDR <= std_logic_vector(to_unsigned(i,16));
-      wait for 10 ps;
-		end loop;
-		wait; -- stop for simulator
-	end process;
-end;
diff --git a/basys3/basys3.srcs/ppu_aux.vhd b/basys3/basys3.srcs/ppu_aux.vhd
new file mode 100644
index 0000000..9062bc4
--- /dev/null
+++ b/basys3/basys3.srcs/ppu_aux.vhd
@@ -0,0 +1,52 @@
+library ieee;
+library work;
+use ieee.std_logic_1164.all;
+--use ieee.numeric_std.all;
+use work.ppu_consts.all;
+
+entity ppu_aux is port(
+	CLK : in std_logic; -- system clock
+	RESET : in std_logic; -- reset memory
+
+	-- internal memory block (AUX)
+	AUX_WEN : in std_logic; -- VRAM AUX write enable
+	AUX_ADDR : in std_logic_vector(PPU_AUX_ADDR_WIDTH-1 downto 0); -- VRAM AUX address
+	AUX_DATA : in std_logic_vector(PPU_AUX_DATA_WIDTH-1 downto 0); -- VRAM AUX data
+	
+	-- aux outputs
+	BG_SHIFT_X : out std_logic_vector(PPU_POS_H_WIDTH-1 downto 0);
+	BG_SHIFT_Y : out std_logic_vector(PPU_POS_V_WIDTH-1 downto 0);
+	FG_FETCH : out std_logic);
+end ppu_aux;
+
+architecture Behavioral of ppu_aux is
+	component er_ram
+		generic(
+			ADDR_W : natural := PPU_AUX_ADDR_WIDTH; -- ADDR line width
+			DATA_W : natural := PPU_AUX_DATA_WIDTH; -- DATA line width
+			ADDR_LOW : natural := 16#0000#; -- starting address
+			ADDR_RANGE : natural := 16#0002#); -- amount of valid addresses after ADDR_LOW
+		port(
+			CLK : in std_logic; -- clock
+			RST : in std_logic; -- async memory clear
+			WEN : in std_logic; -- write enable
+			ADDR : in std_logic_vector(ADDR_W-1 downto 0);
+			DATA : in std_logic_vector(DATA_W-1 downto 0);
+			REG : out std_logic_vector((ADDR_RANGE*DATA_W)-1 downto 0)); -- exposed register output
+	end component;
+
+	signal INT_REG : std_logic_vector(2 * PPU_AUX_DATA_WIDTH - 1 downto 0);
+begin
+	-- docs/architecture.md#auxiliary-memory
+	FG_FETCH <= INT_REG(17);
+	BG_SHIFT_X <= INT_REG(16 downto 8);
+	BG_SHIFT_Y <= INT_REG(7 downto 0);
+
+	RAM : component er_ram port map(
+		CLK => CLK,
+		RST => RESET,
+		WEN => AUX_WEN,
+		ADDR => AUX_ADDR,
+		DATA => AUX_DATA,
+		REG => INT_REG);
+end Behavioral;
diff --git a/basys3/basys3.srcs/ppu_aux_tb.vhd b/basys3/basys3.srcs/ppu_aux_tb.vhd
new file mode 100644
index 0000000..ab3db62
--- /dev/null
+++ b/basys3/basys3.srcs/ppu_aux_tb.vhd
@@ -0,0 +1,100 @@
+library ieee;
+library unisim;
+library work;
+
+use ieee.std_logic_1164.all;
+use ieee.numeric_std.all;
+use unisim.vcomponents.all;
+use work.ppu_consts.all;
+
+entity ppu_aux_tb is
+end ppu_aux_tb;
+
+architecture behavioral of ppu_aux_tb is
+	component ppu_aux port(
+		CLK : in std_logic; -- system clock
+		RESET : in std_logic; -- reset memory
+
+		-- internal memory block (AUX)
+		AUX_WEN : in std_logic; -- VRAM AUX write enable
+		AUX_ADDR : in std_logic_vector(PPU_AUX_ADDR_WIDTH-1 downto 0); -- VRAM AUX address
+		AUX_DATA : in std_logic_vector(PPU_AUX_DATA_WIDTH-1 downto 0); -- VRAM AUX data
+		
+		-- aux outputs
+		BG_SHIFT_X : out std_logic_vector(PPU_POS_H_WIDTH-1 downto 0);
+		BG_SHIFT_Y : out std_logic_vector(PPU_POS_V_WIDTH-1 downto 0);
+		FG_FETCH : out std_logic);
+	end component;
+
+	signal CLK, RST, WEN : std_logic := '0';
+	signal ADDR : std_logic_vector(PPU_AUX_ADDR_WIDTH-1 downto 0) := (others => '0');
+	signal DATA : std_logic_vector(PPU_AUX_DATA_WIDTH-1 downto 0) := (others => '0');
+
+	signal BG_SHIFT_X : std_logic_vector(PPU_POS_H_WIDTH-1 downto 0);
+	signal BG_SHIFT_Y : std_logic_vector(PPU_POS_V_WIDTH-1 downto 0);
+	signal FG_FETCH : std_logic;
+begin
+	uut : component ppu_aux
+		port map(
+			CLK => CLK,
+			RESET => RST,
+			AUX_WEN => WEN,
+			AUX_ADDR => ADDR,
+			AUX_DATA => DATA,
+			BG_SHIFT_X => BG_SHIFT_X,
+			BG_SHIFT_Y => BG_SHIFT_Y,
+			FG_FETCH => FG_FETCH);
+
+	tb : process
+	begin
+		-- reset
+		RST <= '1';
+		wait for 5 ns;
+		RST <= '0';
+		wait for 5 ns;
+
+		WEN <= '1';
+		-- set BG_SHIFT_X to 178
+		-- set BG_SHIFT_Y to 39
+		-- set FG_FETCH to 1
+		ADDR(0) <= '0';
+		DATA <= x"b327";
+
+		CLK <= '1';
+		wait for 1 ns;
+		CLK <= '0';
+		wait for 1 ns;
+
+		ADDR(0) <= '1';
+		DATA <= x"0002";
+
+		CLK <= '1';
+		wait for 1 ns;
+		CLK <= '0';
+		wait for 1 ns;
+
+		wait for 5 ns;
+
+		-- set BG_SHIFT_X to 30
+		-- set BG_SHIFT_Y to 69
+		-- set FG_FETCH to 0
+		ADDR(0) <= '0';
+		DATA <= x"1e45";
+
+		CLK <= '1';
+		wait for 1 ns;
+		CLK <= '0';
+		wait for 1 ns;
+
+		ADDR(0) <= '1';
+		DATA <= x"0000";
+
+		CLK <= '1';
+		wait for 1 ns;
+		CLK <= '0';
+		wait for 1 ns;
+
+
+		wait; -- stop for simulator
+	end process;
+end;
diff --git a/basys3/basys3.srcs/ppu_comp.vhd b/basys3/basys3.srcs/ppu_comp.vhd
new file mode 100644
index 0000000..e79738f
--- /dev/null
+++ b/basys3/basys3.srcs/ppu_comp.vhd
@@ -0,0 +1,36 @@
+library ieee;
+use ieee.std_logic_1164.all;
+use work.ppu_consts.all;
+
+entity ppu_comp is port ( 
+	FG_HIT : in std_logic_vector(PPU_FG_SPRITE_COUNT-1 downto 0);
+	BG_EN : out std_logic;
+	FG_EN : out std_logic_vector(PPU_FG_SPRITE_COUNT-1 downto 0));
+end ppu_comp;
+
+architecture Behavioral of ppu_comp is
+	signal FG_HIT_EMPTY : std_logic_vector(PPU_FG_SPRITE_COUNT-1 downto 0) := (others => '0');
+begin
+	process (FG_HIT)
+		variable HIT : boolean := false;
+	begin
+		-- check if FG_HIT is not empty
+		if FG_HIT /= FG_HIT_EMPTY then
+			BG_EN <= '0';
+			for i in 0 to PPU_FG_SPRITE_COUNT-1 loop
+				-- if FG_HIT is the first one then enable it
+				if(FG_HIT(i) = '1' and HIT = false) then
+					FG_EN(i) <= '1';
+					HIT := true;
+				else
+					-- make rest low
+					FG_EN(i) <= '0';
+				end if;
+			end loop;
+			HIT := false;
+		else
+			BG_EN <= '1';
+			FG_EN <= (others => '0');
+		end if;
+	end process;
+end Behavioral;
diff --git a/basys3/basys3.srcs/ppu_comp_tb.vhd b/basys3/basys3.srcs/ppu_comp_tb.vhd
new file mode 100644
index 0000000..be4c2e3
--- /dev/null
+++ b/basys3/basys3.srcs/ppu_comp_tb.vhd
@@ -0,0 +1,40 @@
+library ieee;
+library unisim;
+use ieee.std_logic_1164.all;
+use work.ppu_consts.all;
+use unisim.vcomponents.all;
+
+entity ppu_comp_tb is
+end ppu_comp_tb;
+
+architecture behavioral of ppu_comp_tb is
+	component ppu_comp port (
+		FG_HIT : in std_logic_vector(PPU_FG_SPRITE_COUNT-1 downto 0);
+		BG_EN : out std_logic;
+		FG_EN : out std_logic_vector(PPU_FG_SPRITE_COUNT-1 downto 0));
+	end component;
+	signal FG_HIT : std_logic_vector(PPU_FG_SPRITE_COUNT-1 downto 0) := (others => '0');
+	signal BG_EN : std_logic := '0';
+	signal FG_EN : std_logic_vector(PPU_FG_SPRITE_COUNT-1 downto 0) := (others => '0');
+begin
+	uut : ppu_comp port map (
+		FG_HIT => FG_HIT,
+		BG_EN => BG_EN,
+		FG_EN => FG_EN
+	);
+	tb : process
+	begin
+		FG_HIT <= (others => '0');
+		wait for 1 ps;
+		FG_HIT(6) <= '1';
+		FG_HIT(5) <= '1';
+		FG_HIT(100) <= '1';
+		wait for 1 ps;
+
+		FG_HIT(0) <= '1';
+		wait for 1 ps;
+		FG_HIT <= (others => '0');
+		wait for 1 ps;
+		wait;
+	end process;
+end Behavioral;
diff --git a/basys3/basys3.srcs/ppu_consts.vhd b/basys3/basys3.srcs/ppu_consts.vhd
index c063586..75b6168 100644
--- a/basys3/basys3.srcs/ppu_consts.vhd
+++ b/basys3/basys3.srcs/ppu_consts.vhd
@@ -1,22 +1,55 @@
+library ieee;
+use ieee.math_real.all;
+
+-- https://docs.google.com/spreadsheets/d/1MU6K4c4PtMR_JXIpc3I0ZJdLZNnoFO7G2P3olCz6LSc
 package ppu_consts is
-	constant PPU_RAM_BUS_ADDR_WIDTH: natural := 16; -- RAM bus address width
-	constant PPU_RAM_BUS_DATA_WIDTH: natural := 16; -- RAM bus data width
-	constant PPU_FG_SPRITE_COUNT: natural := 128; -- amount of foreground sprites
-	constant PPU_COLOR_OUTPUT_DEPTH: natural := 4; -- VGA output channel depth
-	constant PPU_PALETTE_IDX_WIDTH: natural := 3; -- palette index width (within sprite)
-	constant PPU_PALETTE_WIDTH: natural := 3; -- palette index width (palette table)
-	constant PPU_PALETTE_CIDX_WIDTH: natural := PPU_PALETTE_IDX_WIDTH + PPU_PALETTE_WIDTH; -- global palette index width
-	constant PPU_TMM_ADDR_WIDTH: natural := 16;
-	constant PPU_TMM_DATA_WIDTH: natural := 16;
-	constant PPU_BAM_ADDR_WIDTH: natural := 11;
-	constant PPU_BAM_DATA_WIDTH: natural := 15;
-	constant PPU_FAM_ADDR_WIDTH: natural := 8;
-	constant PPU_FAM_DATA_WIDTH: natural := 16;
-	constant PPU_PAL_ADDR_WIDTH: natural := 6;
-	constant PPU_PAL_DATA_WIDTH: natural := 12;
-	constant PPU_AUX_ADDR_WIDTH: natural := 2;
-	constant PPU_AUX_DATA_WIDTH: natural := 16;
-	constant PPU_POS_H_WIDTH: natural := 9; -- amount of bits for horizontal screen offset
-	constant PPU_POS_V_WIDTH: natural := 8; -- amount of bits for vertical screen offset
-end package ppu_consts;
+	-- utility functions
+	function ceil_log2(n : natural) return natural;
 
+	constant PPU_RAM_BUS_ADDR_WIDTH : natural := 16; -- RAM bus address width
+	constant PPU_RAM_BUS_DATA_WIDTH : natural := 16; -- RAM bus data width
+	constant PPU_FG_SPRITE_COUNT : natural := 128; -- foreground sprites
+	constant PPU_COLOR_OUTPUT_DEPTH : natural := 4; -- VGA output channel depth
+	constant PPU_PALETTE_COLOR_WIDTH : natural := 3; -- palette index width (within sprite)
+	constant PPU_PALETTE_INDEX_WIDTH : natural := 3; -- palette index width (palette table)
+	constant PPU_PALETTE_CIDX_WIDTH : natural := (PPU_PALETTE_COLOR_WIDTH + PPU_PALETTE_INDEX_WIDTH); -- global palette index width
+	constant PPU_TMM_ADDR_WIDTH : natural := 16; -- tilemap memory ram bus address width
+	constant PPU_TMM_DATA_WIDTH : natural := 15; -- tilemap memory ram bus data width
+	constant PPU_BAM_ADDR_WIDTH : natural := 11; -- background attribute memory ram bus address width
+	constant PPU_BAM_DATA_WIDTH : natural := 15; -- background attribute memory ram bus data width
+	constant PPU_FAM_ADDR_WIDTH : natural := 8; -- foreground attribute memory ram bus address width
+	constant PPU_FAM_DATA_WIDTH : natural := 16; -- foreground attribute memory ram bus data width
+	constant PPU_PAL_ADDR_WIDTH : natural := 6; -- palette memory ram bus address width
+	constant PPU_PAL_DATA_WIDTH : natural := 12; -- palette memory ram bus data width
+	constant PPU_AUX_ADDR_WIDTH : natural := 1; -- auxiliary memory ram bus address width
+	constant PPU_AUX_DATA_WIDTH : natural := 16; -- auxiliary memory ram bus data width
+	constant PPU_POS_H_WIDTH : natural := 9; -- bits for horizontal screen offset
+	constant PPU_POS_V_WIDTH : natural := 8; -- bits for vertical screen offset
+	constant PPU_SPRITE_WIDTH : natural := 16; -- sprite width (pixels)
+	constant PPU_SPRITE_HEIGHT : natural := 16; -- sprite height (pixels)
+	constant PPU_SPRITE_PIDX_WIDTH : natural := 8; -- bits needed to identify horizontal and vertical pixel within sprite
+	constant PPU_SPRITE_POS_H_WIDTH: natural := 4; -- bits needed to identify horizontal pixel within sprite
+	constant PPU_SPRITE_POS_V_WIDTH: natural := 4; -- bits needed to identify vertical pixel within sprite
+	constant PPU_SCREEN_WIDTH : natural := 320; -- absolute screen width (pixels)
+	constant PPU_SCREEN_HEIGHT : natural := 240; -- absolute screen height (pixels)
+	constant PPU_BG_CANVAS_TILES_H : natural := 40; -- tiles (horizontally) on background canvas
+	constant PPU_BG_CANVAS_TILES_V : natural := 30; -- tiles (vertically) on background canvas
+	constant PPU_BG_CANVAS_TILE_H_WIDTH : natural := 6; -- bits needed to describe horizontal bg tile index (grid coordinates)
+	constant PPU_BG_CANVAS_TILE_V_WIDTH : natural := 5; -- bits needed to describe vertical bg tile index (grid coordinates)
+	constant PPU_TILE_INDEX_WIDTH : natural := 10; -- bits needed to index a tile from TMM memory
+	constant PPU_PIXELS_PER_TILE_WORD : natural := 5; -- pixels defined in one word in TMM memory
+	constant PPU_SPRITE_WORD_COUNT : natural := 52; -- words needed for a single sprite
+	constant PPU_PIXEL_BIT_WIDTH : natural := 3; -- bits needed to identify pixel in TMM word
+	constant PPU_TILE_BIT_WIDTH : natural := (PPU_SPRITE_WIDTH * PPU_SPRITE_HEIGHT * PPU_PALETTE_COLOR_WIDTH); -- bits in single tile
+	constant PPU_TMM_CACHE_FETCH_C_COUNT : natural := PPU_SPRITE_WORD_COUNT + 1;
+	constant PPU_TMM_CACHE_FETCH_A_COUNT : natural := PPU_TMM_CACHE_FETCH_C_COUNT * PPU_FG_SPRITE_COUNT; -- amount of clocks to fetch new TMM cache
+	constant PPU_TMM_CACHE_FETCH_A_WIDTH : natural := ceil_log2(PPU_TMM_CACHE_FETCH_A_COUNT);
+end package ppu_consts;
+package body ppu_consts is
+	-- https://stackoverflow.com/questions/21783280/number-of-bits-to-represent-an-integer-in-vhdl
+	-- Returns number of bits required to represent val in binary vector
+	function ceil_log2(n : natural) return natural is
+	begin
+		return natural(integer(ceil(log2(real(n - 1)))));
+	end function;
+end package body ppu_consts;
diff --git a/basys3/basys3.srcs/ppu_pceg.vhdl b/basys3/basys3.srcs/ppu_pceg.vhd
index 9675e5b..1aaeee4 100644
--- a/basys3/basys3.srcs/ppu_pceg.vhdl
+++ b/basys3/basys3.srcs/ppu_pceg.vhd
@@ -3,18 +3,18 @@ use ieee.std_logic_1164.all;
 --use ieee.numeric_std.all;
 
 entity ppu_pceg is port(
-	CLK: in std_logic; -- system clock
-	RESET: in std_logic; -- async reset
-	SPRITE: out std_logic; -- sprite info fetch + sprite pixel fetch
-	COMP_PAL: out std_logic; -- compositor + palette lookup
-	DONE: out std_logic); -- last pipeline stage done
+	CLK : in std_logic; -- system clock
+	RESET : in std_logic; -- async reset
+	SPRITE : out std_logic; -- sprite info fetch + sprite pixel fetch
+	COMP_PAL : out std_logic; -- compositor + palette lookup
+	DONE : out std_logic); -- last pipeline stage done
 end ppu_pceg;
 
 architecture Behavioral of ppu_pceg is
-	constant PPU_PL_TOTAL_STAGES: natural := 14;
+	constant PPU_PL_TOTAL_STAGES : natural := 14;
 
 	type states is (PL_SPRITE, PL_COMP_PAL, PL_DONE);
-	signal state: states := PL_SPRITE;
+	signal state : states := PL_SPRITE;
 begin
 	-- output drivers
 	SPRITE <= CLK when RESET = '0' and state = PL_SPRITE else '0';
@@ -22,7 +22,7 @@ begin
 	DONE <= '1' when RESET = '0' and state = PL_DONE else '0';
 
 	process(CLK, RESET)
-		variable CLK_IDX: natural range 0 to PPU_PL_TOTAL_STAGES+1 := 0;
+		variable CLK_IDX : natural range 0 to PPU_PL_TOTAL_STAGES+1 := 0;
 	begin
 		if RESET = '1' then
 			state <= PL_SPRITE;
diff --git a/basys3/basys3.srcs/ppu_pceg_tb.vhdl b/basys3/basys3.srcs/ppu_pceg_tb.vhd
index 137d4b4..719ec06 100644
--- a/basys3/basys3.srcs/ppu_pceg_tb.vhdl
+++ b/basys3/basys3.srcs/ppu_pceg_tb.vhd
@@ -10,27 +10,27 @@ end ppu_pceg_tb;
 
 architecture behavioral of ppu_pceg_tb is
 	component ppu_pceg port(
-		CLK: in std_logic; -- system clock
-		RESET: in std_logic; -- async reset
-		SPRITE: out std_logic; -- sprite info fetch + sprite pixel fetch
-		COMP_PAL: out std_logic; -- compositor + palette lookup
-		DONE: out std_logic); -- last pipeline stage done
+		CLK : in std_logic; -- system clock
+		RESET : in std_logic; -- async reset
+		SPRITE : out std_logic; -- sprite info fetch + sprite pixel fetch
+		COMP_PAL : out std_logic; -- compositor + palette lookup
+		DONE : out std_logic); -- last pipeline stage done
 	end component;
-	signal CLK: std_logic := '0';
-	signal RESET: std_logic := '0';
-	signal SPRITE: std_logic;
-	signal COMP_PAL: std_logic;
-	signal DONE: std_logic;
+	signal CLK : std_logic := '0';
+	signal RESET : std_logic := '0';
+	signal SPRITE : std_logic;
+	signal COMP_PAL : std_logic;
+	signal DONE : std_logic;
 
 begin
-	uut: ppu_pceg port map(
+	uut : ppu_pceg port map(
 		CLK => CLK,
 		RESET => RESET,
 		SPRITE => SPRITE,
 		COMP_PAL => COMP_PAL,
 		DONE => DONE);
 
-	tb: process
+	tb : process
 	begin
 		for i in 0 to 32 loop
 			if i > 20 then
diff --git a/basys3/basys3.srcs/ppu_plut.vhd b/basys3/basys3.srcs/ppu_plut.vhd
new file mode 100644
index 0000000..d2e132e
--- /dev/null
+++ b/basys3/basys3.srcs/ppu_plut.vhd
@@ -0,0 +1,69 @@
+library ieee;
+use ieee.std_logic_1164.all;
+use work.ppu_consts.all;
+use ieee.numeric_std.all;
+use ieee.std_logic_unsigned.all;
+
+entity ppu_plut is port ( 
+	CLK : in std_logic; -- system clock
+	CIDX : in std_logic_vector(PPU_PALETTE_CIDX_WIDTH-1 downto 0); -- color in
+	RESET : in std_logic;
+
+	-- internal memory block (AUX)
+	PAL_WEN : in std_logic; -- VRAM PAL write enable
+	PAL_ADDR : in std_logic_vector(PPU_PAL_ADDR_WIDTH-1 downto 0); -- VRAM PAL address
+	PAL_DATA : in std_logic_vector(PPU_PAL_DATA_WIDTH-1 downto 0); -- VRAM PAL data
+
+	R,G,B : out std_logic_vector(PPU_COLOR_OUTPUT_DEPTH-1 downto 0)); -- VGA color out
+end ppu_plut;
+
+architecture Behavioral of ppu_plut is
+	component er_ram
+		generic(
+			ADDR_W : natural := PPU_PAL_ADDR_WIDTH; -- ADDR line width
+			DATA_W : natural := PPU_PAL_DATA_WIDTH; -- DATA line width
+			ADDR_LOW : natural := 16#0000#; -- starting address
+			ADDR_RANGE : natural := 16#0040#); -- amount of valid addresses after ADDR_LOW
+		port(
+			CLK : in std_logic; -- clock
+			RST : in std_logic; -- async memory clear
+			WEN : in std_logic; -- write enable
+			ADDR : in std_logic_vector(ADDR_W-1 downto 0);
+			DATA : in std_logic_vector(DATA_W-1 downto 0);
+			REG : out std_logic_vector((ADDR_RANGE*DATA_W)-1 downto 0)); -- exposed register output
+	end component;
+	
+	signal PLUT : std_logic_vector((64 * PPU_PAL_DATA_WIDTH)-1 downto 0) := (others => '0');
+	signal CHECK_ZERO_CIDX : std_logic_vector(PPU_PALETTE_CIDX_WIDTH-1 downto 0) := (others => '0'); -- color in
+begin
+	RAM : component er_ram port map(
+		CLK => CLK,
+		RST => RESET,
+		WEN => PAL_WEN,
+		ADDR => PAL_ADDR,
+		DATA => PAL_DATA,
+		REG => PLUT);
+
+	process(CLK, RESET)
+		variable COLOR : std_logic_vector(PPU_PAL_DATA_WIDTH-1 downto 0) := (others => '0'); -- COLORS RGB IN
+		variable CIDX_INT : integer := 0;
+	begin
+		if RESET = '1' then
+			PLUT <= (others => '0');
+		else
+			if rising_edge (CLK) then
+				if (CIDX /= CHECK_ZERO_CIDX) then
+					CIDX_INT := to_integer(unsigned(CIDX));
+					COLOR := PLUT((12 * CIDX_INT) + 11 downto (12*CIDX_INT));
+					R <= COLOR(11 downto  8);
+					G <= COLOR(7 downto 4);
+					B <= COLOR(3 downto 0);
+				else
+					R <= x"0";
+					G <= x"0";
+					B <= x"0";
+				end if;
+			end if;
+		end if;
+	end process;
+end Behavioral;
diff --git a/basys3/basys3.srcs/ppu_sprite_bg.vhd b/basys3/basys3.srcs/ppu_sprite_bg.vhd
new file mode 100644
index 0000000..dba5b8e
--- /dev/null
+++ b/basys3/basys3.srcs/ppu_sprite_bg.vhd
@@ -0,0 +1,138 @@
+library ieee;
+library work;
+
+use ieee.std_logic_1164.all;
+use ieee.std_logic_unsigned.all;
+use ieee.numeric_std.all;
+use work.ppu_consts.all;
+
+-- TODO: add input stable / output stable pipeline stages if this doesn't work with propagation delays
+entity ppu_sprite_bg is port(
+	-- inputs
+	CLK : in std_logic; -- pipeline clock
+	RESET : in std_logic; -- reset clock counter
+	OE : in std_logic; -- output enable (of CIDX)
+	X : in std_logic_vector(PPU_POS_H_WIDTH-1 downto 0); -- current screen pixel x
+	Y : in std_logic_vector(PPU_POS_V_WIDTH-1 downto 0); -- current screen pixel y
+	
+	-- aux inputs
+	BG_SHIFT_X : in std_logic_vector(PPU_POS_H_WIDTH-1 downto 0);
+	BG_SHIFT_Y : in std_logic_vector(PPU_POS_V_WIDTH-1 downto 0);
+
+	-- used memory blocks
+	BAM_ADDR : out std_logic_vector(PPU_BAM_ADDR_WIDTH-1 downto 0);
+	BAM_DATA : in std_logic_vector(PPU_BAM_DATA_WIDTH-1 downto 0);
+	TMM_ADDR : out std_logic_vector(PPU_TMM_ADDR_WIDTH-1 downto 0);
+	TMM_DATA : in std_logic_vector(PPU_TMM_DATA_WIDTH-1 downto 0);
+
+	-- outputs
+	CIDX : out std_logic_vector(PPU_PALETTE_CIDX_WIDTH-1 downto 0)); -- output color
+end ppu_sprite_bg;
+
+architecture Behavioral of ppu_sprite_bg is
+	component ppu_sprite_transform port(
+		XI : in unsigned(PPU_SPRITE_POS_H_WIDTH-1 downto 0); -- pixel position relative to tile
+		YI : in unsigned(PPU_SPRITE_POS_V_WIDTH-1 downto 0); -- pixel position relative to tile
+		FLIP_H, FLIP_V : in std_logic; -- flip sprite
+		XO : out unsigned(PPU_SPRITE_POS_H_WIDTH-1 downto 0); -- new pixel position relative to tile
+		YO : out unsigned(PPU_SPRITE_POS_V_WIDTH-1 downto 0)); -- new pixel position relative to tile
+	end component;
+
+	-- BAM and TMM in/out temp + registers
+	signal T_BAM_ADDR, R_BAM_ADDR : std_logic_vector(PPU_BAM_ADDR_WIDTH-1 downto 0) := (others => '0');
+	signal T_BAM_DATA, R_BAM_DATA : std_logic_vector(PPU_BAM_DATA_WIDTH-1 downto 0) := (others => '0');
+	signal T_TMM_ADDR, R_TMM_ADDR : std_logic_vector(PPU_TMM_ADDR_WIDTH-1 downto 0) := (others => '0');
+	signal T_TMM_DATA, R_TMM_DATA : std_logic_vector(PPU_TMM_DATA_WIDTH-1 downto 0) := (others => '0');
+
+	-- state machine for synchronizing pipeline stages
+	type states is (PL_BAM_ADDR, PL_BAM_DATA, PL_TMM_ADDR, PL_TMM_DATA);
+	signal state : states := PL_BAM_ADDR;
+
+	-- docs/architecture.md#background-attribute-memory
+	alias BAM_DATA_FLIP_H is R_BAM_DATA(14); -- flip horizontally
+	alias BAM_DATA_FLIP_V is R_BAM_DATA(13); -- flip vertically
+	alias BAM_DATA_TILE_IDX is R_BAM_DATA(9 downto 0); -- tilemap tile index
+	alias BAM_DATA_COL_IDX is R_BAM_DATA(12 downto 10); -- palette for sprite
+
+	-- auxiliary signals (temp variables)
+	signal PIXEL_ABS_X, PIXEL_ABS_Y : integer := 0; -- absolute pixel position (relative to BG canvas instead of viewport)
+	signal TILE_IDX_X, TILE_IDX_Y : integer := 0; -- background canvas tile grid xy
+	signal TILE_PIDX_X, TRANS_TILE_PIDX_X : unsigned(PPU_SPRITE_POS_H_WIDTH-1 downto 0) := (others => '0'); -- x position of pixel within tile (local tile coords)
+	signal TILE_PIDX_Y, TRANS_TILE_PIDX_Y : unsigned(PPU_SPRITE_POS_V_WIDTH-1 downto 0) := (others => '0'); -- y position of pixel within tile (local tile coords)
+	signal TRANS_TILE_PIDX : integer := 0; -- index of pixel within tile (reading order)
+	signal TILEMAP_WORD_OFFSET : integer := 0; -- word offset from tile start address in TMM
+	signal PIXEL_BIT_OFFSET : integer := 0; -- pixel index within word of TMM
+	signal TMM_DATA_PAL_IDX : std_logic_vector(PPU_PALETTE_COLOR_WIDTH-1 downto 0); -- color of palette
+	signal T_CIDX : std_logic_vector(PPU_PALETTE_CIDX_WIDTH-1 downto 0) := (others => '0'); -- output color buffer/register
+begin
+	-- output drivers
+	CIDX <= T_CIDX when OE = '1' else (others => 'Z');
+	BAM_ADDR <= R_BAM_ADDR;
+	TMM_ADDR <= R_TMM_ADDR;
+	T_BAM_DATA <= BAM_DATA;
+	T_TMM_DATA <= TMM_DATA;
+	-- CIDX combination
+	T_CIDX <= BAM_DATA_COL_IDX & TMM_DATA_PAL_IDX;
+
+	-- BAM address calculations
+	PIXEL_ABS_X <= to_integer(unsigned(X)) + to_integer(unsigned(BG_SHIFT_X)); -- pixel position relative to background canvas
+	PIXEL_ABS_Y <= to_integer(unsigned(Y)) + to_integer(unsigned(BG_SHIFT_Y)); -- pixel position relative to background canvas
+	TILE_IDX_X <= PIXEL_ABS_X / 16; -- tile grid index
+	TILE_IDX_Y <= PIXEL_ABS_Y / 16; -- tile grid index
+	TILE_PIDX_X <= to_unsigned(PIXEL_ABS_X - TILE_IDX_X * 16, TILE_PIDX_X'length); -- (sprite local) pixel coords
+	TILE_PIDX_Y <= to_unsigned(PIXEL_ABS_Y - TILE_IDX_Y * 16, TILE_PIDX_Y'length); -- (sprite local) pixel coords
+	T_BAM_ADDR <= std_logic_vector(to_unsigned((TILE_IDX_Y * integer(PPU_BG_CANVAS_TILES_H)) + TILE_IDX_X, PPU_BAM_ADDR_WIDTH));
+
+	-- BAM data dependant calculations
+	transform: component ppu_sprite_transform port map(
+		XI => TILE_PIDX_X,
+		YI => TILE_PIDX_Y,
+		FLIP_H => BAM_DATA_FLIP_H,
+		FLIP_V => BAM_DATA_FLIP_V,
+		XO => TRANS_TILE_PIDX_X,
+		YO => TRANS_TILE_PIDX_Y);
+
+	-- TMM address calculations
+	TRANS_TILE_PIDX <= integer(PPU_SPRITE_WIDTH) * to_integer(TRANS_TILE_PIDX_Y) + to_integer(TRANS_TILE_PIDX_X); -- pixel index of sprite
+	TILEMAP_WORD_OFFSET <= TRANS_TILE_PIDX / PPU_PIXELS_PER_TILE_WORD; -- word offset from starting word of sprite
+	PIXEL_BIT_OFFSET <= TRANS_TILE_PIDX mod PPU_PIXELS_PER_TILE_WORD; -- pixel bit offset
+	T_TMM_ADDR <= std_logic_vector(to_unsigned(PPU_SPRITE_WORD_COUNT * to_integer(unsigned(BAM_DATA_TILE_IDX)) + TILEMAP_WORD_OFFSET, PPU_TMM_ADDR_WIDTH)); -- TMM address
+
+	-- TMM DATA
+	with PIXEL_BIT_OFFSET select
+		TMM_DATA_PAL_IDX <= R_TMM_DATA(2 downto 0) when 0,
+		                    R_TMM_DATA(5 downto 3) when 1,
+		                    R_TMM_DATA(8 downto 6) when 2,
+		                    R_TMM_DATA(11 downto 9) when 3,
+		                    R_TMM_DATA(14 downto 12) when 4,
+		                    (others => '0') when others;
+
+	-- state machine (pipeline stage counter) + sync r/w
+	process(CLK, RESET)
+	begin
+		if RESET = '1' then
+			-- reset state
+			state <= PL_BAM_ADDR;
+			-- reset internal pipeline registers
+			R_BAM_ADDR <= (others => '0');
+			R_BAM_DATA <= (others => '0');
+			R_TMM_ADDR <= (others => '0');
+			R_TMM_DATA <= (others => '0');
+		elsif rising_edge(CLK) then
+			case state is
+				when PL_BAM_ADDR =>
+					state <= PL_BAM_DATA;
+					R_BAM_ADDR <= T_BAM_ADDR;
+				when PL_BAM_DATA =>
+					state <= PL_TMM_ADDR;
+					R_BAM_DATA <= T_BAM_DATA;
+				when PL_TMM_ADDR =>
+					state <= PL_TMM_DATA;
+					R_TMM_ADDR <= T_TMM_ADDR;
+				when PL_TMM_DATA =>
+					state <= PL_BAM_ADDR;
+					R_TMM_DATA <= T_TMM_DATA;
+			end case;
+		end if;
+	end process;
+end Behavioral;
diff --git a/basys3/basys3.srcs/ppu_sprite_bg_tb.vhd b/basys3/basys3.srcs/ppu_sprite_bg_tb.vhd
new file mode 100644
index 0000000..65da15c
--- /dev/null
+++ b/basys3/basys3.srcs/ppu_sprite_bg_tb.vhd
@@ -0,0 +1,107 @@
+library ieee;
+library work;
+library unisim;
+
+use ieee.std_logic_1164.all;
+use ieee.numeric_std.all;
+use unisim.vcomponents.all;
+use work.ppu_consts.all;
+
+entity ppu_sprite_bg_tb is
+end ppu_sprite_bg_tb;
+
+architecture Behavioral of ppu_sprite_bg_tb is
+	component ppu_sprite_bg port(
+		-- inputs
+		CLK : in std_logic; -- pipeline clock
+		RESET : in std_logic; -- reset clock counter
+		OE : in std_logic; -- output enable (of CIDX)
+		X : in std_logic_vector(PPU_POS_H_WIDTH-1 downto 0); -- current screen pixel x
+		Y : in std_logic_vector(PPU_POS_V_WIDTH-1 downto 0); -- current screen pixel y
+		
+		-- aux inputs
+		BG_SHIFT_X : in std_logic_vector(PPU_POS_H_WIDTH-1 downto 0);
+		BG_SHIFT_Y : in std_logic_vector(PPU_POS_V_WIDTH-1 downto 0);
+
+		-- used memory blocks
+		BAM_ADDR : out std_logic_vector(PPU_BAM_ADDR_WIDTH-1 downto 0);
+		BAM_DATA : in std_logic_vector(PPU_BAM_DATA_WIDTH-1 downto 0);
+		TMM_ADDR : out std_logic_vector(PPU_TMM_ADDR_WIDTH-1 downto 0);
+		TMM_DATA : in std_logic_vector(PPU_TMM_DATA_WIDTH-1 downto 0);
+
+		-- outputs
+		CIDX : out std_logic_vector(PPU_PALETTE_CIDX_WIDTH-1 downto 0)); -- output color
+	end component;
+	signal CLK : std_logic := '0'; -- pipeline clock
+	signal RESET : std_logic := '0'; -- reset clock counter
+	signal OE : std_logic := '0'; -- output enable (of CIDX)
+	signal X : std_logic_vector(PPU_POS_H_WIDTH-1 downto 0) := (others => '0'); -- current screen pixel x
+	signal Y : std_logic_vector(PPU_POS_V_WIDTH-1 downto 0) := (others => '0'); -- current screen pixel y
+	signal BG_SHIFT_X : std_logic_vector(PPU_POS_H_WIDTH-1 downto 0) := (others => '0');
+	signal BG_SHIFT_Y : std_logic_vector(PPU_POS_V_WIDTH-1 downto 0) := (others => '0');
+	signal BAM_ADDR : std_logic_vector(PPU_BAM_ADDR_WIDTH-1 downto 0);
+	signal BAM_DATA : std_logic_vector(PPU_BAM_DATA_WIDTH-1 downto 0) := (others => '0');
+	signal TMM_ADDR : std_logic_vector(PPU_TMM_ADDR_WIDTH-1 downto 0);
+	signal TMM_DATA : std_logic_vector(PPU_TMM_DATA_WIDTH-1 downto 0) := (others => '0');
+	signal CIDX : std_logic_vector(PPU_PALETTE_CIDX_WIDTH-1 downto 0); -- output color
+begin
+	uut : ppu_sprite_bg port map(
+		CLK => CLK,
+		RESET => RESET,
+		OE => OE,
+		X => X,
+		Y => Y,
+		BG_SHIFT_X => BG_SHIFT_X,
+		BG_SHIFT_Y => BG_SHIFT_Y,
+		BAM_ADDR => BAM_ADDR,
+		BAM_DATA => BAM_DATA,
+		TMM_ADDR => TMM_ADDR,
+		TMM_DATA => TMM_DATA,
+		CIDX => CIDX);
+
+	-- inputs
+	-- BAM_DATA -> FLIP_H + palette index 2 + tilemap index 10
+	-- TMM_DATA -> all pixels color 7
+	-- X -> 25
+	-- Y -> 60
+	-- BG_SHIFT_X -> 3
+	-- BG_SHIFT_Y -> 3
+	BAM_DATA <= 15x"4814"; -- hex((1 << 14) | (0 << 13) | (2 << 10) | (20 << 0))
+	TMM_DATA <= 15x"7e3f"; -- hex(0x7fff & ~(0b111 << 6))
+	X <= std_logic_vector(to_unsigned(25, PPU_POS_H_WIDTH));
+	Y <= std_logic_vector(to_unsigned(60, PPU_POS_V_WIDTH));
+	BG_SHIFT_X <= std_logic_vector(to_unsigned(3, PPU_POS_H_WIDTH));
+	BG_SHIFT_Y <= std_logic_vector(to_unsigned(3, PPU_POS_V_WIDTH));
+
+	-- expected outputs:
+	-- absolute pixel coordinates -> (28, 63)
+	-- absolute background canvas tile index coordinates -> (1, 3)
+	-- tile index -> 3 * 40 + 1 = 121
+	-- BAM_ADDR => 121 (OK)
+	-- sprite local coordinates -> (12, 15)
+	-- transformed local coordinates -> (12, 0) (apply FLIP_H)
+	-- pixel index -> 0 * 16 + 12 = 12
+	-- pixel word address -> 52 * 20 + 12//5 -> 1042
+	-- TMM_ADDR => 1042 (OK)
+	-- pixel bits -> [pixel n+] = 12 % 5 = 2 -> 8 downto 6
+	-- cidx should be -- (2 << 3) | (0 << 0) = 16
+	-- CIDX => 16 (OK)
+
+	tb : process
+	begin
+		for i in 0 to 32 loop
+			if i > 10 then
+				OE <= '1';
+			end if;
+			if i > 20 then
+				RESET <= '1';
+			end if;
+	
+			wait for 5 ns;
+			CLK <= '1';
+			wait for 5 ns;
+			CLK <= '0';
+		end loop;
+		wait; -- stop for simulator
+	end process;
+end Behavioral;
diff --git a/basys3/basys3.srcs/ppu_sprite_fg.vhd b/basys3/basys3.srcs/ppu_sprite_fg.vhd
new file mode 100644
index 0000000..af7cfa3
--- /dev/null
+++ b/basys3/basys3.srcs/ppu_sprite_fg.vhd
@@ -0,0 +1,192 @@
+library ieee;
+library work;
+
+use ieee.std_logic_1164.all;
+use ieee.std_logic_unsigned.all;
+use ieee.numeric_std.all;
+use work.ppu_consts.all;
+
+-- TODO: add input stable / output stable pipeline stages if this doesn't work with propagation delays
+entity ppu_sprite_fg is -- foreground sprite
+	generic (
+		IDX : natural := 0); -- sprite index number
+	port(
+		-- inputs
+		CLK : in std_logic; -- system clock
+		RESET : in std_logic; -- reset internal memory and clock counters
+		OE : in std_logic; -- output enable (of CIDX)
+		X : in std_logic_vector(PPU_POS_H_WIDTH-1 downto 0); -- current screen pixel x
+		Y : in std_logic_vector(PPU_POS_V_WIDTH-1 downto 0); -- current screen pixel y
+		FETCH : in std_logic; -- fetch sprite data from TMM
+		VBLANK : in std_logic; -- fetch during vblank
+
+		-- internal memory block (FAM)
+		FAM_WEN : in std_logic; -- VRAM FAM write enable
+		FAM_ADDR : in std_logic_vector(PPU_FAM_ADDR_WIDTH-1 downto 0); -- VRAM fam address
+		FAM_DATA : in std_logic_vector(PPU_FAM_DATA_WIDTH-1 downto 0); -- VRAM fam data
+
+		-- used memory blocks
+		TMM_ADDR : out std_logic_vector(PPU_TMM_ADDR_WIDTH-1 downto 0);
+		TMM_DATA : in std_logic_vector(PPU_TMM_DATA_WIDTH-1 downto 0);
+
+		-- outputs
+		CIDX : out std_logic_vector(PPU_PALETTE_CIDX_WIDTH-1 downto 0); -- output color
+		HIT : out std_logic); -- current pixel is not transparent
+end ppu_sprite_fg;
+
+architecture Behavioral of ppu_sprite_fg is
+	component ppu_sprite_transform port(
+		XI : in unsigned(PPU_SPRITE_POS_H_WIDTH-1 downto 0); -- pixel position relative to tile
+		YI : in unsigned(PPU_SPRITE_POS_V_WIDTH-1 downto 0); -- pixel position relative to tile
+		FLIP_H, FLIP_V : in std_logic; -- flip sprite
+		XO : out unsigned(PPU_SPRITE_POS_H_WIDTH-1 downto 0); -- new pixel position relative to tile
+		YO : out unsigned(PPU_SPRITE_POS_V_WIDTH-1 downto 0)); -- new pixel position relative to tile
+	end component;
+	component er_ram -- exposed register RAM
+		generic(
+			ADDR_W : natural := 2; -- ADDR line width
+			DATA_W : natural := 2; -- DATA line width
+			ADDR_LOW : natural := 16#0000#; -- starting address
+			ADDR_RANGE : natural := 16#0002#); -- amount of valid addresses after ADDR_LOW
+		port(
+			CLK : in std_logic; -- clock
+			RST : in std_logic; -- async memory clear
+			WEN : in std_logic; -- write enable
+			ADDR : in std_logic_vector(ADDR_W-1 downto 0); -- address line
+			DATA : in std_logic_vector(DATA_W-1 downto 0); -- data input
+			REG : out std_logic_vector((ADDR_RANGE*DATA_W)-1 downto 0)); -- exposed register output
+	end component;
+
+	-- FAM and TMM in/out lines
+	signal T_TMM_ADDR : std_logic_vector(PPU_TMM_ADDR_WIDTH-1 downto 0) := (others => '0');
+	signal T_TMM_DATA : std_logic_vector(PPU_TMM_DATA_WIDTH-1 downto 0) := (others => '0');
+
+	-- auxiliary signals (temp variables)
+	signal T_CIDX : std_logic_vector(PPU_PALETTE_CIDX_WIDTH-1 downto 0) := (others => '0'); -- output color buffer/register
+	signal INT_FAM : std_logic_vector(31 downto 0);
+
+	-- FAM aliases (docs/architecture.md#foreground-attribute-memory)
+	alias FAM_REG_FLIP_H is INT_FAM(31); -- Flip horizontally
+	alias FAM_REG_FLIP_V is INT_FAM(30); -- Flip vertically
+	alias FAM_REG_POS_H is INT_FAM(29 downto 21); -- horizontal position (offset by -16)
+	alias FAM_REG_POS_V is INT_FAM(20 downto 13); -- vertical position (offset by -16)
+	alias FAM_REG_COL_IDX is INT_FAM(12 downto 10); -- Palette index for tile
+	alias FAM_REG_TILE_IDX is INT_FAM(9 downto 0); -- Tilemap index
+
+	signal SPRITE_ACTIVE : std_logic := '0'; -- is pixel in bounding box of sprite
+	signal PIXEL_ABS_X, PIXEL_ABS_Y : integer := 0; -- absolute pixel position (relative to FG canvas instead of viewport)
+	signal TILE_PIDX_X, TRANS_TILE_PIDX_X : unsigned(PPU_SPRITE_POS_H_WIDTH-1 downto 0) := (others => '0'); -- xy position of pixel within tile (local tile coords)
+	signal TILE_PIDX_Y, TRANS_TILE_PIDX_Y : unsigned(PPU_SPRITE_POS_V_WIDTH-1 downto 0) := (others => '0'); -- xy position of pixel within tile (local tile coords)
+	signal TRANS_TILE_PIXEL_IDX : integer := 0; -- index of pixel within tile (reading order)
+	signal TILEMAP_WORD_OFFSET : integer := 0; -- word offset from tile start address in TMM
+	signal TMM_DATA_PAL_IDX : std_logic_vector(PPU_PALETTE_COLOR_WIDTH-1 downto 0); -- color of palette
+
+	-- TMM cache lines
+	signal TMM_CACHE_WEN, TMM_CACHE_UPDATE_TURN : std_logic := '0';
+	signal TMM_CACHE_DATA : std_logic_vector(PPU_TMM_DATA_WIDTH-1 downto 0) := (others => '0');
+	signal TMM_CACHE_ADDR : std_logic_vector(PPU_TMM_ADDR_WIDTH-1 downto 0) := (others => '0');
+	signal TMM_CACHE : std_logic_vector((PPU_SPRITE_WORD_COUNT * PPU_TMM_DATA_WIDTH)-1 downto 0);
+begin
+	-- output drivers
+	CIDX <= T_CIDX when OE = '1' else (others => 'Z');
+	-- CIDX combination
+	T_CIDX <= FAM_REG_COL_IDX & TMM_DATA_PAL_IDX;
+
+	-- FAM memory
+	FAM : component er_ram
+		generic map(
+			ADDR_W => PPU_FAM_ADDR_WIDTH,
+			DATA_W => PPU_FAM_DATA_WIDTH,
+			ADDR_LOW => IDX*2,
+			ADDR_RANGE => 2)
+		port map(
+			CLK => CLK,
+			RST => RESET,
+			WEN => FAM_WEN,
+			ADDR => FAM_ADDR,
+			DATA => FAM_DATA,
+			REG => INT_FAM);
+
+	-- pixel position within bounding box of sprite
+	SPRITE_ACTIVE <= '1' when ((unsigned(X) + 16) >= unsigned(FAM_REG_POS_H)) and
+	                          ((unsigned(X) + 16) < (unsigned(FAM_REG_POS_H) + to_unsigned(PPU_SPRITE_WIDTH, PPU_POS_H_WIDTH))) and
+	                          ((unsigned(Y) + 16) >= unsigned(FAM_REG_POS_V)) and
+	                          ((unsigned(Y) + 16) < (unsigned(FAM_REG_POS_V) + to_unsigned(PPU_SPRITE_HEIGHT, PPU_POS_V_WIDTH))) else '0';
+
+	-- (sprite local) pixel coords
+	TILE_PIDX_X <= resize(unsigned(X) + 16 - resize(unsigned(FAM_REG_POS_H), TILE_PIDX_X'length), TILE_PIDX_X'length);
+	TILE_PIDX_Y <= resize(unsigned(Y) + 16 - resize(unsigned(FAM_REG_POS_V), TILE_PIDX_Y'length), TILE_PIDX_Y'length);
+
+	-- transform local coords
+	transform: component ppu_sprite_transform port map(
+		XI => TILE_PIDX_X,
+		YI => TILE_PIDX_Y,
+		FLIP_H => FAM_REG_FLIP_H,
+		FLIP_V => FAM_REG_FLIP_V,
+		XO => TRANS_TILE_PIDX_X,
+		YO => TRANS_TILE_PIDX_Y);
+
+	-- pixel index
+	TRANS_TILE_PIXEL_IDX <= integer(PPU_SPRITE_WIDTH) * to_integer(TRANS_TILE_PIDX_Y) + to_integer(TRANS_TILE_PIDX_X);
+	-- palette color at pixel
+	TMM_DATA_PAL_IDX <= TMM_CACHE(TRANS_TILE_PIXEL_IDX * integer(PPU_PALETTE_COLOR_WIDTH) + integer(PPU_PALETTE_COLOR_WIDTH)-1 downto TRANS_TILE_PIXEL_IDX * integer(PPU_PALETTE_COLOR_WIDTH));
+	-- if pixel in sprite hitbox and TMM_DATA_PAL_IDX > 0
+	HIT <= SPRITE_ACTIVE and (nor TMM_DATA_PAL_IDX);
+
+	-- FETCH LOGIC BELOW
+	TMM_ADDR <= T_TMM_ADDR when TMM_CACHE_UPDATE_TURN else (others => 'Z');
+	T_TMM_DATA <= TMM_DATA;
+
+	-- TTM cache
+	ttm_cache : component er_ram
+		generic map(
+			ADDR_W => PPU_TMM_ADDR_WIDTH,
+			DATA_W => PPU_TMM_DATA_WIDTH,
+			ADDR_LOW => 0,
+			ADDR_RANGE => PPU_SPRITE_WORD_COUNT)
+		port map(
+			CLK => CLK,
+			RST => RESET,
+			WEN => TMM_CACHE_WEN,
+			ADDR => TMM_CACHE_ADDR,
+			DATA => TMM_CACHE_DATA,
+			REG => TMM_CACHE);
+
+	-- fetch machine, should do the following (offset data read by one clock -> propagation/lookup delay):
+	-- CLK[53 * IDX + 0] (addr = 0)
+	-- CLK[53 * IDX + 1] (addr = 1, read data[0])
+	-- CLK[53 * IDX + 2] (addr = 2, read data[1]), etc
+	-- a full tile is 52 words, but since the offset is 1 clock, a total copy takes 53 clock cycles
+	process(CLK, RESET, FETCH)
+		constant TMM_FETCH_CLK_RANGE_BEGIN : natural := PPU_TMM_CACHE_FETCH_C_COUNT * IDX; -- fetch CLK count for copying this module's sprite from TMM
+		variable TMM_FETCH_CTR : unsigned(PPU_TMM_CACHE_FETCH_A_WIDTH-1 downto 0) := (others => '0'); -- CLK counter while FETCH=1
+		variable TMM_FETCH_CTR_REL : unsigned(PPU_TMM_CACHE_FETCH_A_WIDTH-1 downto 0) := (others => '0'); -- CLK counter relative for sprite[IDX]
+	begin
+		if RESET = '1' or FETCH = '0' then
+			TMM_FETCH_CTR := (others => '0');
+			TMM_FETCH_CTR_REL := (others => '0');
+			TMM_CACHE_WEN <= '0';
+			TMM_CACHE_UPDATE_TURN <= '0';
+		elsif rising_edge(CLK) then
+			TMM_FETCH_CTR := TMM_FETCH_CTR + 1;
+			TMM_FETCH_CTR_REL := TMM_FETCH_CTR - TMM_FETCH_CLK_RANGE_BEGIN;
+
+			if TMM_FETCH_CTR >= TMM_FETCH_CLK_RANGE_BEGIN and
+			   TMM_FETCH_CTR < (TMM_FETCH_CLK_RANGE_BEGIN + PPU_TMM_CACHE_FETCH_C_COUNT) then
+				TMM_CACHE_UPDATE_TURN <= '1';
+				if TMM_FETCH_CTR_REL < PPU_TMM_CACHE_FETCH_C_COUNT - 1 then -- calculate address until second to last clock
+					T_TMM_ADDR <= std_logic_vector(resize(TMM_FETCH_CTR - IDX, T_TMM_ADDR'length));
+					TMM_CACHE_ADDR <= std_logic_vector(resize(TMM_FETCH_CTR_REL - 1, TMM_CACHE_ADDR'length));
+				end if;
+
+				if TMM_FETCH_CTR_REL > 0 then -- read offset
+					TMM_CACHE_DATA <= T_TMM_DATA;
+					TMM_CACHE_WEN <= '1';
+				end if;
+			else
+				TMM_CACHE_WEN <= '0';
+				TMM_CACHE_UPDATE_TURN <= '0';
+			end if;
+		end if;
+	end process;
+end Behavioral;
diff --git a/basys3/basys3.srcs/ppu_sprite_fg_tb.vhd b/basys3/basys3.srcs/ppu_sprite_fg_tb.vhd
new file mode 100644
index 0000000..19b9f35
--- /dev/null
+++ b/basys3/basys3.srcs/ppu_sprite_fg_tb.vhd
@@ -0,0 +1,140 @@
+library ieee;
+library work;
+library unisim;
+
+use ieee.std_logic_1164.all;
+use ieee.numeric_std.all;
+use unisim.vcomponents.all;
+use work.ppu_consts.all;
+
+entity ppu_sprite_fg_tb is
+end ppu_sprite_fg_tb;
+
+architecture Behavioral of ppu_sprite_fg_tb is
+	component ppu_sprite_fg -- foreground sprite
+		generic (
+			IDX : natural := 0); -- sprite index number
+		port(
+			-- inputs
+			CLK : in std_logic; -- system clock
+			RESET : in std_logic; -- reset internal memory and clock counters
+			OE : in std_logic; -- output enable (of CIDX)
+			X : in std_logic_vector(PPU_POS_H_WIDTH-1 downto 0); -- current screen pixel x
+			Y : in std_logic_vector(PPU_POS_V_WIDTH-1 downto 0); -- current screen pixel y
+			FETCH : in std_logic; -- fetch sprite data from TMM
+			VBLANK : in std_logic; -- fetch during vblank
+
+			-- internal memory block (FAM)
+			FAM_WEN : in std_logic; -- VRAM FAM write enable
+			FAM_ADDR : in std_logic_vector(PPU_FAM_ADDR_WIDTH-1 downto 0); -- VRAM fam address
+			FAM_DATA : in std_logic_vector(PPU_FAM_DATA_WIDTH-1 downto 0); -- VRAM fam data
+
+			-- used memory blocks
+			TMM_ADDR : out std_logic_vector(PPU_TMM_ADDR_WIDTH-1 downto 0);
+			TMM_DATA : in std_logic_vector(PPU_TMM_DATA_WIDTH-1 downto 0);
+
+			-- outputs
+			CIDX : out std_logic_vector(PPU_PALETTE_CIDX_WIDTH-1 downto 0); -- output color
+			HIT : out std_logic); -- current pixel is not transparent
+	end component;
+	signal CLK : std_logic := '0';
+	signal RESET : std_logic := '0';
+	signal OE : std_logic := '0';
+	signal X : std_logic_vector(PPU_POS_H_WIDTH-1 downto 0) := (others => '0');
+	signal Y : std_logic_vector(PPU_POS_V_WIDTH-1 downto 0) := (others => '0');
+	signal FETCH : std_logic := '0';
+	signal VBLANK : std_logic := '0';
+	signal FAM_WEN : std_logic := '0';
+	signal FAM_ADDR : std_logic_vector(PPU_FAM_ADDR_WIDTH-1 downto 0) := (others => '0');
+	signal FAM_DATA : std_logic_vector(PPU_FAM_DATA_WIDTH-1 downto 0) := (others => '0');
+	signal TMM_ADDR : std_logic_vector(PPU_TMM_ADDR_WIDTH-1 downto 0);
+	signal TMM_DATA : std_logic_vector(PPU_TMM_DATA_WIDTH-1 downto 0) := (others => '0');
+	signal CIDX : std_logic_vector(PPU_PALETTE_CIDX_WIDTH-1 downto 0) := (others => '0');
+	signal HIT : std_logic;
+
+	signal CLK_I : unsigned(31 downto 0) := (others => '0');
+begin
+	uut: component ppu_sprite_fg
+		generic map( IDX => 2 )
+		port map(
+			CLK => CLK,
+			RESET => RESET,
+			OE => OE,
+			X => X,
+			Y => Y,
+			FETCH => FETCH,
+			VBLANK => VBLANK,
+			FAM_WEN => FAM_WEN,
+			FAM_ADDR => FAM_ADDR,
+			FAM_DATA => FAM_DATA,
+			TMM_ADDR => TMM_ADDR,
+			TMM_DATA => TMM_DATA,
+			CIDX => CIDX,
+			HIT => HIT);
+
+	tb : process
+	begin
+		-- initialize TMM cache
+		RESET <= '1'; wait for 1 ns; RESET <= '0'; wait for 1 ns;
+
+		OE <= '1';
+		VBLANK <= '0';
+		FETCH <= '0';
+
+		-- FAM contents:
+		-- flip horizontally
+		-- xy -> (42-16, 8-16) = (26, -8)
+		-- palette index 2
+		-- tilemap index 460 (0x1cc)
+		-- = hex((1 << 31) | (0 << 30) | (42 << 21) | (8 << 13) | (2 << 10) | (460 << 0))
+		FAM_WEN <= '1';
+		FAM_ADDR <= std_logic_vector(to_unsigned(16#0005#, FAM_ADDR'length));
+		FAM_DATA <= std_logic_vector(to_unsigned(16#8541#, FAM_DATA'length));
+		CLK <= '1'; wait for 1 ns; CLK <= '0'; wait for 1 ns;
+		FAM_ADDR <= std_logic_vector(to_unsigned(16#0004#, FAM_ADDR'length));
+		FAM_DATA <= std_logic_vector(to_unsigned(16#09cc#, FAM_DATA'length));
+		CLK <= '1'; wait for 1 ns; CLK <= '0'; wait for 1 ns;
+		FAM_WEN <= '0';
+
+		for i in 0 to 32 loop
+			if i = 0 then
+				X <= std_logic_vector(to_unsigned(25, X'length));
+				Y <= std_logic_vector(to_unsigned(60, Y'length));
+			end if;
+
+			if i = 3 then
+				X <= std_logic_vector(to_unsigned(29, X'length));
+				Y <= std_logic_vector(to_unsigned(4, Y'length));
+			end if;
+	
+			wait for 5 ns; CLK <= '1'; wait for 5 ns; CLK <= '0';
+		end loop;
+
+		wait for 1 ns;
+		RESET <= '1';
+		wait for 10 ns;
+		RESET <= '0';
+		VBLANK <= '1';
+		FETCH <= '1';
+		wait for 1 ns;
+
+		-- FETCH check
+		for i in 0 to 500 loop
+			CLK_I <= to_unsigned(i, 32);
+			-- if i > 10 then
+			-- 	OE <= '1';
+			-- end if;
+			-- if i > 20 then
+			-- 	RESET <= '1';
+			-- end if;
+
+			TMM_DATA <= std_logic_vector(to_unsigned(i - 106, TMM_DATA'length));
+	
+			CLK <= '1';
+			wait for 1 ns;
+			CLK <= '0';
+			wait for 1 ns;
+		end loop;
+		wait; -- stop for simulator
+	end process;
+end Behavioral;
diff --git a/basys3/basys3.srcs/ppu_sprite_transform.vhd b/basys3/basys3.srcs/ppu_sprite_transform.vhd
new file mode 100644
index 0000000..f94616c
--- /dev/null
+++ b/basys3/basys3.srcs/ppu_sprite_transform.vhd
@@ -0,0 +1,24 @@
+library ieee;
+library work;
+use ieee.std_logic_1164.all;
+use ieee.numeric_std.all;
+use work.ppu_consts.all;
+
+entity ppu_sprite_transform is port( -- flip sprites
+	XI : in unsigned(PPU_SPRITE_POS_H_WIDTH-1 downto 0); -- pixel position relative to tile
+	YI : in unsigned(PPU_SPRITE_POS_V_WIDTH-1 downto 0); -- pixel position relative to tile
+	FLIP_H, FLIP_V : in std_logic; -- flip sprite
+	XO : out unsigned(PPU_SPRITE_POS_H_WIDTH-1 downto 0); -- new pixel position relative to tile
+	YO : out unsigned(PPU_SPRITE_POS_V_WIDTH-1 downto 0)); -- new pixel position relative to tile
+end ppu_sprite_transform;
+
+architecture Behavioral of ppu_sprite_transform is
+	signal FLIPPED_X : unsigned(PPU_SPRITE_POS_H_WIDTH-1 downto 0);
+	signal FLIPPED_Y : unsigned(PPU_SPRITE_POS_V_WIDTH-1 downto 0);
+begin
+	FLIPPED_X <= to_unsigned(PPU_SPRITE_WIDTH-1, PPU_SPRITE_POS_H_WIDTH) - XI;
+	FLIPPED_Y <= to_unsigned(PPU_SPRITE_HEIGHT-1, PPU_SPRITE_POS_V_WIDTH) - YI;
+
+	XO <= FLIPPED_X when FLIP_V = '1' else XI;
+	YO <= FLIPPED_Y when FLIP_H = '1' else YI;
+end Behavioral;
diff --git a/basys3/basys3.srcs/ppu_sprite_transform_tb.vhd b/basys3/basys3.srcs/ppu_sprite_transform_tb.vhd
new file mode 100644
index 0000000..516a653
--- /dev/null
+++ b/basys3/basys3.srcs/ppu_sprite_transform_tb.vhd
@@ -0,0 +1,66 @@
+library ieee;
+library unisim;
+library work;
+
+use ieee.std_logic_1164.all;
+use ieee.numeric_std.all;
+use unisim.vcomponents.all;
+use work.ppu_consts.all;
+
+entity ppu_sprite_transform_tb is
+end ppu_sprite_transform_tb;
+
+architecture behavioral of ppu_sprite_transform_tb is
+	component ppu_sprite_transform port( -- flip sprites
+		XI : in unsigned(PPU_SPRITE_POS_H_WIDTH-1 downto 0); -- pixel position relative to tile
+		YI : in unsigned(PPU_SPRITE_POS_V_WIDTH-1 downto 0); -- pixel position relative to tile
+		FLIP_H, FLIP_V : in std_logic; -- flip sprite
+		XO : out unsigned(PPU_SPRITE_POS_H_WIDTH-1 downto 0); -- new pixel position relative to tile
+		YO : out unsigned(PPU_SPRITE_POS_V_WIDTH-1 downto 0)); -- new pixel position relative to tile
+	end component;
+
+	signal XI : unsigned(PPU_SPRITE_POS_H_WIDTH-1 downto 0);
+	signal YI : unsigned(PPU_SPRITE_POS_V_WIDTH-1 downto 0);
+	signal FLIP_H, FLIP_V : std_logic := '0';
+	signal XO : unsigned(PPU_SPRITE_POS_H_WIDTH-1 downto 0);
+	signal YO : unsigned(PPU_SPRITE_POS_V_WIDTH-1 downto 0);
+begin
+	uut : component ppu_sprite_transform
+		port map(
+			XI => XI,
+			YI => YI,
+			FLIP_H => FLIP_H,
+			FLIP_V => FLIP_V,
+			XO => XO,
+			YO => YO);
+
+	tb : process
+	begin
+		XI <= to_unsigned(4, PPU_SPRITE_POS_H_WIDTH);
+		YI <= to_unsigned(6, PPU_SPRITE_POS_V_WIDTH);
+		wait for 5 ns;
+
+		XI <= to_unsigned(2, PPU_SPRITE_POS_H_WIDTH);
+		YI <= to_unsigned(14, PPU_SPRITE_POS_V_WIDTH);
+		wait for 5 ns;
+
+		FLIP_H <= '1';
+		wait for 5 ns;
+
+		FLIP_V <= '1';
+		wait for 5 ns;
+
+		XI <= to_unsigned(6, PPU_SPRITE_POS_H_WIDTH);
+		YI <= to_unsigned(8, PPU_SPRITE_POS_V_WIDTH);
+		wait for 5 ns;
+
+		FLIP_H <= '0';
+		wait for 5 ns;
+
+		XI <= to_unsigned(2, PPU_SPRITE_POS_H_WIDTH);
+		YI <= to_unsigned(14, PPU_SPRITE_POS_V_WIDTH);
+		wait for 5 ns;
+
+		wait; -- stop for simulator
+	end process;
+end;
diff --git a/basys3/basys3.srcs/ppu_vga_native.vhd b/basys3/basys3.srcs/ppu_vga_native.vhd
new file mode 100644
index 0000000..47288e9
--- /dev/null
+++ b/basys3/basys3.srcs/ppu_vga_native.vhd
@@ -0,0 +1,95 @@
+library ieee;
+use ieee.std_logic_1164.all;
+use work.ppu_consts.all;
+use ieee.numeric_std.all;
+use ieee.std_logic_unsigned.all;
+
+entity ppu_vga_native is port (
+	CLK: in std_logic; -- system clock
+	RESET: in std_logic;
+
+	X: in std_logic_vector(PPU_POS_H_WIDTH-1 downto 0); -- current screen pixel x
+	Y: in std_logic_vector(PPU_POS_V_WIDTH-1 downto 0); -- current screen pixel y
+	PREADY: in std_logic; -- current pixel ready (pixel color is stable)
+	RI,GI,BI: in std_logic_vector(PPU_COLOR_OUTPUT_DEPTH-1 downto 0); -- VGA color in
+
+	RO,GO,BO: out std_logic_vector(PPU_COLOR_OUTPUT_DEPTH-1 downto 0); -- VGA color out
+	VSYNC, HSYNC: out std_logic); -- VGA sync outputs
+end ppu_vga_native;
+
+architecture Behavioral of ppu_vga_native is
+	type line_buffer is array(319 downto 0) of std_logic_vector(11 downto 0);
+	signal ram_x0 : line_buffer; -- buffer 0
+	signal ram_x1: line_buffer; -- buffer 1
+	signal hcount: std_logic_vector(9 downto 0):= (others => '0');
+	signal vcount: std_logic_vector(9 downto 0):= (others => '0');
+	signal clk_counter: std_logic_vector(1 downto 0):= (others => '0');
+	signal rgb_out : std_logic_vector(11 downto 0):= (others => '0'); -- output colors
+	signal px : integer; -- conversion for hcount
+	signal py :integer; -- conversion for vcount
+	signal buffer_filled_on_buffer0 : integer;
+	signal buffer_filled_on_buffer1 : integer;
+begin
+	process (clk, x, y)
+		variable v_x : integer; -- integer to hold vector X
+	begin
+		if rising_edge(clk) then
+			clk_counter <= clk_counter + 1;
+			if clk_counter = "11" then
+				v_x := to_integer(unsigned(x) - 72);
+				if v_x >= 0 and v_x < 320 and PREADY = '1' then
+					if y(0) = '0' then
+						ram_x0(v_x) <= RI & GI & BI;
+						if v_x = 319 then
+							buffer_filled_on_buffer0 <= to_integer(unsigned(y) - 14);
+						end if;
+					else
+						ram_x1(v_x) <= RI & GI & BI;
+						if v_x = 319 then
+							buffer_filled_on_buffer1 <= to_integer(unsigned(y) - 14);
+						end if;
+					end if;
+				end if;
+				-- T display(display data)
+				if (hcount >= 144) and (hcount < 784) and (vcount >= 31) and (vcount < 511) then
+					px <= to_integer(unsigned(hcount) - 144);
+					py <= to_integer(unsigned(vcount) - 31);
+					if buffer_filled_on_buffer0 = (py/2) then
+						rgb_out <= ram_x0(px/2);
+					elsif buffer_filled_on_buffer1 = (py/2) then
+						rgb_out <= ram_x1(px/2);
+					else
+						rgb_out <= (others => '0');
+					end if;
+				end if;
+				-- pulse width
+				hsync <= '1';
+				if hcount < 97 then
+					hsync <= '0';
+				end if;
+
+				vsync <= '1';
+				if vcount < 3 then
+					vsync <= '0';
+				end if;
+
+				-- sync pulse time
+				hcount <= hcount + 1;
+
+				if hcount = 800 then
+					vcount <= vcount + 1;
+					hcount <= (others => '0');
+				end if;
+
+				if vcount = 521 then
+					vcount <= (others => '0');
+				end if;
+			end if;
+
+			-- output colors
+		RO <= rgb_out(11 downto 8);
+		GO <= rgb_out(7 downto 4);
+		BO <= rgb_out(3 downto 0);
+		end if;
+	end process;
+end Behavioral;
diff --git a/basys3/basys3.srcs/ppu_vga_native_tb.vhd b/basys3/basys3.srcs/ppu_vga_native_tb.vhd
new file mode 100644
index 0000000..06061a0
--- /dev/null
+++ b/basys3/basys3.srcs/ppu_vga_native_tb.vhd
@@ -0,0 +1,89 @@
+library ieee;
+library unisim;
+use ieee.std_logic_1164.all;
+use work.ppu_consts.all;
+use ieee.numeric_std.all;
+use ieee.std_logic_unsigned.all;
+use unisim.vcomponents.all;
+
+entity ppu_vga_native_tb is
+end ppu_vga_native_tb;
+
+architecture Behavioral of ppu_vga_native_tb is
+	component ppu_vga_native port (
+		CLK : in std_logic; -- system clock
+		RESET : in std_logic;
+
+		X : in std_logic_vector(PPU_POS_H_WIDTH-1 downto 0); -- current screen pixel x
+		Y : in std_logic_vector(PPU_POS_V_WIDTH-1 downto 0); -- current screen pixel y
+		PREADY : in std_logic; -- current pixel ready (pixel color is stable)
+		RI,GI,BI : in std_logic_vector(PPU_COLOR_OUTPUT_DEPTH-1 downto 0); -- VGA color in
+
+		RO,GO,BO : out std_logic_vector(PPU_COLOR_OUTPUT_DEPTH-1 downto 0); -- VGA color out
+		VSYNC, HSYNC : out std_logic); -- VGA sync outputs
+	end component;
+	signal CLK : std_logic := '0';
+	signal RST : std_logic := '0';
+	signal PREADY : std_logic := '0';
+
+	signal X : std_logic_vector(PPU_POS_H_WIDTH-1 downto 0) := (others => '0');
+	signal Y : std_logic_vector(PPU_POS_V_WIDTH-1 downto 0) := (others => '0');
+
+	signal RI,GI,BI : std_logic_vector(PPU_COLOR_OUTPUT_DEPTH-1 downto 0) := (others => '0'); -- VGA color in
+	signal RO,GO,BO : std_logic_vector(PPU_COLOR_OUTPUT_DEPTH-1 downto 0) := (others => '0'); -- VGA color out
+	signal VSYNC, HSYNC :  std_logic := '0';
+
+	signal Xas : integer := 72;
+	signal Yas : integer := 14;
+	signal counter : std_logic_vector(1 downto 0) := (others => '0');
+begin
+	uut : ppu_vga_native port map(
+		CLK => CLK,
+		RESET => RST,
+		X => X,
+		Y => Y,
+		PREADY => PREADY,
+		RI => RI,
+		GI => GI,
+		BI => BI,
+		RO => RO,
+		GO => GO,
+		BO => BO,
+		VSYNC => VSYNC,
+		HSYNC => HSYNC
+	);
+
+	tb : process
+	begin
+		CLK <= '1';
+		wait for 1 ps;
+		CLK <= '0';
+		wait for 1 ps;
+	end process;
+
+	process(CLK)
+	begin
+		if rising_edge(CLK) then
+			counter <= counter + 1;
+		end if;
+
+		if(counter = "11") then
+			pready <= '1';
+			ri <= x"d";
+			gi <= x"a";
+			bi <= x"d";
+			x <= std_logic_vector(to_unsigned(Xas, x'length));
+			if (Xas = 391) then
+				Xas <= 72;
+				y <= std_logic_vector(to_unsigned(Yas, y'length));
+				if (Yas = 255) then
+					Yas <= 14;
+				else
+					Yas <= Yas + 1;
+				end if;
+			else
+				Xas <= Xas + 1;
+			end if;
+		end if;
+	end process;
+end Behavioral;
diff --git a/basys3/basys3.srcs/ppu_vga_tiny.vhd b/basys3/basys3.srcs/ppu_vga_tiny.vhd
new file mode 100644
index 0000000..0e496f6
--- /dev/null
+++ b/basys3/basys3.srcs/ppu_vga_tiny.vhd
@@ -0,0 +1,73 @@
+library ieee;
+use ieee.std_logic_1164.all;
+use work.ppu_consts.all;
+use ieee.numeric_std.all;
+use ieee.std_logic_unsigned.all;
+
+entity ppu_vga_tiny is port (
+	CLK : in std_logic; -- system clock
+	RESET : in std_logic;
+
+	X : out std_logic_vector(PPU_POS_H_WIDTH-1 downto 0); -- current screen pixel x
+	Y : out std_logic_vector(PPU_POS_V_WIDTH-1 downto 0); -- current screen pixel y
+
+	VSYNC, VBLANK,
+	HSYNC, HBLANK : out std_logic); -- VGA sync outputs
+end ppu_vga_tiny;
+
+architecture Behavioral of ppu_vga_tiny is
+	signal hcount : std_logic_vector(PPU_POS_H_WIDTH-1 downto 0) := (others => '0');
+	signal vcount : std_logic_vector(PPU_POS_V_WIDTH-1 downto 0) := (others => '0');
+	signal clk_counter : std_logic_vector(4 downto 0) := (others => '0');
+begin
+	process (CLK)
+	begin
+		if rising_edge(CLK) then
+			clk_counter <= clk_counter + 1;
+			if(clk_counter > 15) then
+				clk_counter <= (others => '0');
+				-- x,y data out
+				X <= hcount;
+				Y <= vcount;
+
+				--pulse width
+				if hcount < 32 or hcount >= 320-80 then
+					hsync <= '0';
+				else
+					hsync <= '1';
+				end if;
+
+				if vcount < 8 or vcount >= 240-15 then
+					vsync <= '0';
+				else
+					vsync <= '1';
+				end if;
+
+				-- Hblank and Vblank outputs
+				if hcount >= 320-80 then
+					hblank <= '1';
+				else
+					hblank <= '0';
+				end if;
+
+				if vcount >= 240-15 then
+					vblank <= '1';
+				else
+					vblank <= '0';
+				end if;
+
+				-- sync pulse time
+				hcount <= hcount + 1;
+
+				if hcount = 400 then
+					vcount <= vcount + 1;
+					hcount <= (others => '0');
+				end if;
+
+				if vcount = 255 then
+					vcount <= (others => '0');
+				end if;
+			end if;
+		end if;
+	end process;
+end Behavioral;
diff --git a/basys3/basys3.srcs/sources_1/ip/ppu_bam/ppu_bam.xci b/basys3/basys3.srcs/sources_1/ip/ppu_bam/ppu_bam.xci
index f5e1696..e299ea1 100644
--- a/basys3/basys3.srcs/sources_1/ip/ppu_bam/ppu_bam.xci
+++ b/basys3/basys3.srcs/sources_1/ip/ppu_bam/ppu_bam.xci
@@ -163,7 +163,7 @@
         "BOARD_CONNECTIONS": [ { "value": "" } ],
         "DEVICE": [ { "value": "xc7a35t" } ],
         "PACKAGE": [ { "value": "cpg236" } ],
-        "PREFHDL": [ { "value": "VERILOG" } ],
+        "PREFHDL": [ { "value": "VHDL" } ],
         "SILICON_REVISION": [ { "value": "" } ],
         "SIMULATOR_LANGUAGE": [ { "value": "MIXED" } ],
         "SPEEDGRADE": [ { "value": "-1" } ],
diff --git a/basys3/basys3.srcs/sources_1/ip/ppu_tmm/ppu_tmm.xci b/basys3/basys3.srcs/sources_1/ip/ppu_tmm/ppu_tmm.xci
index 51914b1..9663635 100644
--- a/basys3/basys3.srcs/sources_1/ip/ppu_tmm/ppu_tmm.xci
+++ b/basys3/basys3.srcs/sources_1/ip/ppu_tmm/ppu_tmm.xci
@@ -14,7 +14,7 @@
         "Use_AXI_ID": [ { "value": "false", "resolve_type": "user", "format": "bool", "enabled": false, "usage": "all" } ],
         "AXI_ID_Width": [ { "value": "4", "resolve_type": "user", "format": "long", "enabled": false, "usage": "all" } ],
         "Memory_Type": [ { "value": "Single_Port_RAM", "resolve_type": "user", "usage": "all" } ],
-        "PRIM_type_to_Implement": [ { "value": "BRAM", "resolve_type": "user", "usage": "all" } ],
+        "PRIM_type_to_Implement": [ { "value": "BRAM", "resolve_type": "user", "enabled": false, "usage": "all" } ],
         "Enable_32bit_Address": [ { "value": "false", "resolve_type": "user", "format": "bool", "usage": "all" } ],
         "ecctype": [ { "value": "No_ECC", "resolve_type": "user", "enabled": false, "usage": "all" } ],
         "ECC": [ { "value": "false", "resolve_type": "user", "format": "bool", "enabled": false, "usage": "all" } ],
@@ -32,13 +32,13 @@
         "Algorithm": [ { "value": "Minimum_Area", "resolve_type": "user", "usage": "all" } ],
         "Primitive": [ { "value": "8kx2", "resolve_type": "user", "enabled": false, "usage": "all" } ],
         "Assume_Synchronous_Clk": [ { "value": "false", "resolve_type": "user", "format": "bool", "enabled": false, "usage": "all" } ],
-        "Write_Width_A": [ { "value": "16", "resolve_type": "user", "format": "long", "usage": "all" } ],
-        "Write_Depth_A": [ { "value": "49152", "value_src": "user", "resolve_type": "user", "format": "long", "usage": "all" } ],
-        "Read_Width_A": [ { "value": "16", "resolve_type": "user", "usage": "all" } ],
+        "Write_Width_A": [ { "value": "15", "value_src": "user", "resolve_type": "user", "format": "long", "usage": "all" } ],
+        "Write_Depth_A": [ { "value": "53248", "value_src": "user", "resolve_type": "user", "format": "long", "usage": "all" } ],
+        "Read_Width_A": [ { "value": "15", "resolve_type": "user", "usage": "all" } ],
         "Operating_Mode_A": [ { "value": "WRITE_FIRST", "resolve_type": "user", "usage": "all" } ],
         "Enable_A": [ { "value": "Always_Enabled", "value_src": "user", "resolve_type": "user", "usage": "all" } ],
-        "Write_Width_B": [ { "value": "16", "resolve_type": "user", "enabled": false, "usage": "all" } ],
-        "Read_Width_B": [ { "value": "16", "resolve_type": "user", "enabled": false, "usage": "all" } ],
+        "Write_Width_B": [ { "value": "15", "resolve_type": "user", "enabled": false, "usage": "all" } ],
+        "Read_Width_B": [ { "value": "15", "resolve_type": "user", "enabled": false, "usage": "all" } ],
         "Operating_Mode_B": [ { "value": "WRITE_FIRST", "resolve_type": "user", "enabled": false, "usage": "all" } ],
         "Enable_B": [ { "value": "Always_Enabled", "resolve_type": "user", "enabled": false, "usage": "all" } ],
         "Register_PortA_Output_of_Memory_Primitives": [ { "value": "true", "resolve_type": "user", "format": "bool", "usage": "all" } ],
@@ -110,10 +110,10 @@
         "C_USE_BYTE_WEA": [ { "value": "0", "resolve_type": "generated", "format": "long", "usage": "all" } ],
         "C_WEA_WIDTH": [ { "value": "1", "resolve_type": "generated", "format": "long", "usage": "all" } ],
         "C_WRITE_MODE_A": [ { "value": "WRITE_FIRST", "resolve_type": "generated", "usage": "all" } ],
-        "C_WRITE_WIDTH_A": [ { "value": "16", "resolve_type": "generated", "format": "long", "usage": "all" } ],
-        "C_READ_WIDTH_A": [ { "value": "16", "resolve_type": "generated", "format": "long", "usage": "all" } ],
-        "C_WRITE_DEPTH_A": [ { "value": "49152", "resolve_type": "generated", "format": "long", "usage": "all" } ],
-        "C_READ_DEPTH_A": [ { "value": "49152", "resolve_type": "generated", "format": "long", "usage": "all" } ],
+        "C_WRITE_WIDTH_A": [ { "value": "15", "resolve_type": "generated", "format": "long", "usage": "all" } ],
+        "C_READ_WIDTH_A": [ { "value": "15", "resolve_type": "generated", "format": "long", "usage": "all" } ],
+        "C_WRITE_DEPTH_A": [ { "value": "53248", "resolve_type": "generated", "format": "long", "usage": "all" } ],
+        "C_READ_DEPTH_A": [ { "value": "53248", "resolve_type": "generated", "format": "long", "usage": "all" } ],
         "C_ADDRA_WIDTH": [ { "value": "16", "resolve_type": "generated", "format": "long", "usage": "all" } ],
         "C_HAS_RSTB": [ { "value": "0", "resolve_type": "generated", "format": "long", "usage": "all" } ],
         "C_RST_PRIORITY_B": [ { "value": "CE", "resolve_type": "generated", "usage": "all" } ],
@@ -124,10 +124,10 @@
         "C_USE_BYTE_WEB": [ { "value": "0", "resolve_type": "generated", "format": "long", "usage": "all" } ],
         "C_WEB_WIDTH": [ { "value": "1", "resolve_type": "generated", "format": "long", "usage": "all" } ],
         "C_WRITE_MODE_B": [ { "value": "WRITE_FIRST", "resolve_type": "generated", "usage": "all" } ],
-        "C_WRITE_WIDTH_B": [ { "value": "16", "resolve_type": "generated", "format": "long", "usage": "all" } ],
-        "C_READ_WIDTH_B": [ { "value": "16", "resolve_type": "generated", "format": "long", "usage": "all" } ],
-        "C_WRITE_DEPTH_B": [ { "value": "49152", "resolve_type": "generated", "format": "long", "usage": "all" } ],
-        "C_READ_DEPTH_B": [ { "value": "49152", "resolve_type": "generated", "format": "long", "usage": "all" } ],
+        "C_WRITE_WIDTH_B": [ { "value": "15", "resolve_type": "generated", "format": "long", "usage": "all" } ],
+        "C_READ_WIDTH_B": [ { "value": "15", "resolve_type": "generated", "format": "long", "usage": "all" } ],
+        "C_WRITE_DEPTH_B": [ { "value": "53248", "resolve_type": "generated", "format": "long", "usage": "all" } ],
+        "C_READ_DEPTH_B": [ { "value": "53248", "resolve_type": "generated", "format": "long", "usage": "all" } ],
         "C_ADDRB_WIDTH": [ { "value": "16", "resolve_type": "generated", "format": "long", "usage": "all" } ],
         "C_HAS_MEM_OUTPUT_REGS_A": [ { "value": "1", "resolve_type": "generated", "format": "long", "usage": "all" } ],
         "C_HAS_MEM_OUTPUT_REGS_B": [ { "value": "0", "resolve_type": "generated", "format": "long", "usage": "all" } ],
@@ -153,9 +153,9 @@
         "C_EN_SHUTDOWN_PIN": [ { "value": "0", "resolve_type": "generated", "format": "long", "usage": "all" } ],
         "C_EN_SAFETY_CKT": [ { "value": "1", "resolve_type": "generated", "format": "long", "usage": "all" } ],
         "C_DISABLE_WARN_BHV_RANGE": [ { "value": "0", "resolve_type": "generated", "format": "long", "usage": "all" } ],
-        "C_COUNT_36K_BRAM": [ { "value": "22", "resolve_type": "generated", "usage": "all" } ],
-        "C_COUNT_18K_BRAM": [ { "value": "1", "resolve_type": "generated", "usage": "all" } ],
-        "C_EST_POWER_SUMMARY": [ { "value": "Estimated Power for IP     :     16.534446 mW", "resolve_type": "generated", "usage": "all" } ]
+        "C_COUNT_36K_BRAM": [ { "value": "19", "resolve_type": "generated", "usage": "all" } ],
+        "C_COUNT_18K_BRAM": [ { "value": "8", "resolve_type": "generated", "usage": "all" } ],
+        "C_EST_POWER_SUMMARY": [ { "value": "Estimated Power for IP     :     13.861152 mW", "resolve_type": "generated", "usage": "all" } ]
       },
       "project_parameters": {
         "ARCHITECTURE": [ { "value": "artix7" } ],
@@ -163,7 +163,7 @@
         "BOARD_CONNECTIONS": [ { "value": "" } ],
         "DEVICE": [ { "value": "xc7a35t" } ],
         "PACKAGE": [ { "value": "cpg236" } ],
-        "PREFHDL": [ { "value": "VERILOG" } ],
+        "PREFHDL": [ { "value": "VHDL" } ],
         "SILICON_REVISION": [ { "value": "" } ],
         "SIMULATOR_LANGUAGE": [ { "value": "MIXED" } ],
         "SPEEDGRADE": [ { "value": "-1" } ],
@@ -189,8 +189,8 @@
         "rsta": [ { "direction": "in", "driver_value": "0" } ],
         "wea": [ { "direction": "in", "size_left": "0", "size_right": "0", "driver_value": "0" } ],
         "addra": [ { "direction": "in", "size_left": "15", "size_right": "0", "driver_value": "0" } ],
-        "dina": [ { "direction": "in", "size_left": "15", "size_right": "0", "driver_value": "0" } ],
-        "douta": [ { "direction": "out", "size_left": "15", "size_right": "0" } ],
+        "dina": [ { "direction": "in", "size_left": "14", "size_right": "0", "driver_value": "0" } ],
+        "douta": [ { "direction": "out", "size_left": "14", "size_right": "0" } ],
         "rsta_busy": [ { "direction": "out" } ]
       },
       "interfaces": {
diff --git a/basys3/basys3.xpr b/basys3/basys3.xpr
index 466cc1f..4060a21 100644
--- a/basys3/basys3.xpr
+++ b/basys3/basys3.xpr
@@ -42,8 +42,10 @@
     <Option Name="SimulatorGccVersionVCS" Val="9.2.0"/>
     <Option Name="SimulatorGccVersionRiviera" Val="9.3.0"/>
     <Option Name="SimulatorGccVersionActiveHdl" Val="9.3.0"/>
+    <Option Name="TargetLanguage" Val="VHDL"/>
     <Option Name="BoardPart" Val="digilentinc.com:basys3:part0:1.2"/>
     <Option Name="BoardPartRepoPaths" Val="$PPRDIR/../../../../.Xilinx/Vivado/2022.2/xhub/board_store/xilinx_board_store"/>
+    <Option Name="SourceMgmtMode" Val="DisplayOnly"/>
     <Option Name="ActiveSimSet" Val="sim_1"/>
     <Option Name="DefaultLib" Val="xil_defaultlib"/>
     <Option Name="ProjectType" Val="Default"/>
@@ -59,20 +61,20 @@
     <Option Name="IPStaticSourceDir" Val="$PIPUSERFILESDIR/ipstatic"/>
     <Option Name="EnableBDX" Val="FALSE"/>
     <Option Name="DSABoardId" Val="basys3"/>
-    <Option Name="WTXSimLaunchSim" Val="12"/>
+    <Option Name="WTXSimLaunchSim" Val="113"/>
     <Option Name="WTModelSimLaunchSim" Val="0"/>
     <Option Name="WTQuestaLaunchSim" Val="0"/>
     <Option Name="WTIesLaunchSim" Val="0"/>
     <Option Name="WTVcsLaunchSim" Val="0"/>
     <Option Name="WTRivieraLaunchSim" Val="0"/>
     <Option Name="WTActivehdlLaunchSim" Val="0"/>
-    <Option Name="WTXSimExportSim" Val="3"/>
-    <Option Name="WTModelSimExportSim" Val="3"/>
-    <Option Name="WTQuestaExportSim" Val="3"/>
+    <Option Name="WTXSimExportSim" Val="4"/>
+    <Option Name="WTModelSimExportSim" Val="4"/>
+    <Option Name="WTQuestaExportSim" Val="4"/>
     <Option Name="WTIesExportSim" Val="0"/>
-    <Option Name="WTVcsExportSim" Val="3"/>
-    <Option Name="WTRivieraExportSim" Val="3"/>
-    <Option Name="WTActivehdlExportSim" Val="3"/>
+    <Option Name="WTVcsExportSim" Val="4"/>
+    <Option Name="WTRivieraExportSim" Val="4"/>
+    <Option Name="WTActivehdlExportSim" Val="4"/>
     <Option Name="GenerateIPUpgradeLog" Val="TRUE"/>
     <Option Name="XSimRadix" Val="hex"/>
     <Option Name="XSimTimeUnit" Val="ns"/>
@@ -96,20 +98,20 @@
           <Attr Name="UsedIn" Val="simulation"/>
         </FileInfo>
       </File>
-      <File Path="$PSRCDIR/ppu_addr_dec.vhdl">
-        <FileInfo>
+      <File Path="$PSRCDIR/ppu_pceg.vhd">
+        <FileInfo SFType="VHDL2008">
           <Attr Name="UsedIn" Val="synthesis"/>
           <Attr Name="UsedIn" Val="simulation"/>
         </FileInfo>
       </File>
-      <File Path="$PSRCDIR/ppu_pceg.vhdl">
-        <FileInfo>
+      <File Path="$PSRCDIR/ppu.vhd">
+        <FileInfo SFType="VHDL2008">
           <Attr Name="UsedIn" Val="synthesis"/>
           <Attr Name="UsedIn" Val="simulation"/>
         </FileInfo>
       </File>
-      <File Path="$PSRCDIR/ppu.vhd">
-        <FileInfo>
+      <File Path="$PSRCDIR/ppu_addr_dec.vhd">
+        <FileInfo SFType="VHDL2008">
           <Attr Name="UsedIn" Val="synthesis"/>
           <Attr Name="UsedIn" Val="simulation"/>
         </FileInfo>
@@ -117,7 +119,6 @@
       <File Path="$PSRCDIR/apu.vhd">
         <FileInfo>
           <Attr Name="UserDisabled" Val="1"/>
-          <Attr Name="AutoDisabled" Val="1"/>
           <Attr Name="UsedIn" Val="synthesis"/>
           <Attr Name="UsedIn" Val="simulation"/>
         </FileInfo>
@@ -125,7 +126,73 @@
       <File Path="$PSRCDIR/apu_note_to_frequency.vhd">
         <FileInfo>
           <Attr Name="UserDisabled" Val="1"/>
-          <Attr Name="AutoDisabled" Val="1"/>
+          <Attr Name="UsedIn" Val="synthesis"/>
+          <Attr Name="UsedIn" Val="simulation"/>
+        </FileInfo>
+      </File>
+      <File Path="$PSRCDIR/er_ram.vhd">
+        <FileInfo SFType="VHDL2008">
+          <Attr Name="UsedIn" Val="synthesis"/>
+          <Attr Name="UsedIn" Val="simulation"/>
+        </FileInfo>
+      </File>
+      <File Path="$PSRCDIR/er_ram_mod.vhd">
+        <FileInfo SFType="VHDL2008">
+          <Attr Name="UsedIn" Val="synthesis"/>
+          <Attr Name="UsedIn" Val="simulation"/>
+        </FileInfo>
+      </File>
+      <File Path="$PSRCDIR/ppu_aux.vhd">
+        <FileInfo SFType="VHDL2008">
+          <Attr Name="UsedIn" Val="synthesis"/>
+          <Attr Name="UsedIn" Val="simulation"/>
+        </FileInfo>
+      </File>
+      <File Path="$PSRCDIR/ppu_sprite_bg.vhd">
+        <FileInfo>
+          <Attr Name="UsedIn" Val="synthesis"/>
+          <Attr Name="UsedIn" Val="simulation"/>
+        </FileInfo>
+      </File>
+      <File Path="$PSRCDIR/ppu_sprite_transform.vhd">
+        <FileInfo>
+          <Attr Name="UsedIn" Val="synthesis"/>
+          <Attr Name="UsedIn" Val="simulation"/>
+        </FileInfo>
+      </File>
+      <File Path="$PSRCDIR/ppu_sprite_fg.vhd">
+        <FileInfo SFType="VHDL2008">
+          <Attr Name="UsedIn" Val="synthesis"/>
+          <Attr Name="UsedIn" Val="simulation"/>
+        </FileInfo>
+      </File>
+      <File Path="$PSRCDIR/ppu_vga_tiny.vhd">
+        <FileInfo>
+          <Attr Name="UsedIn" Val="synthesis"/>
+          <Attr Name="UsedIn" Val="simulation"/>
+        </FileInfo>
+      </File>
+      <File Path="$PSRCDIR/ppu_comp.vhd">
+        <FileInfo>
+          <Attr Name="UsedIn" Val="synthesis"/>
+          <Attr Name="UsedIn" Val="simulation"/>
+        </FileInfo>
+      </File>
+      <File Path="$PSRCDIR/ppu_plut.vhd">
+        <FileInfo>
+          <Attr Name="UsedIn" Val="synthesis"/>
+          <Attr Name="UsedIn" Val="simulation"/>
+        </FileInfo>
+      </File>
+      <File Path="$PSRCDIR/ppu_vga_native.vhd">
+        <FileInfo>
+          <Attr Name="UsedIn" Val="synthesis"/>
+          <Attr Name="UsedIn" Val="simulation"/>
+        </FileInfo>
+      </File>
+      <File Path="$PSRCDIR/apu_lut_reader.vhd">
+        <FileInfo>
+          <Attr Name="UserDisabled" Val="1"/>
           <Attr Name="UsedIn" Val="synthesis"/>
           <Attr Name="UsedIn" Val="simulation"/>
         </FileInfo>
@@ -144,15 +211,14 @@
     </FileSet>
     <FileSet Name="sim_1" Type="SimulationSrcs" RelSrcDir="$PSRCDIR/sim_1" RelGenDir="$PGENDIR/sim_1">
       <Filter Type="Srcs"/>
-      <File Path="$PSRCDIR/ppu_addr_dec_tb.vhdl">
+      <File Path="$PSRCDIR/ppu_addr_dec_tb.vhd">
         <FileInfo>
           <Attr Name="UsedIn" Val="synthesis"/>
           <Attr Name="UsedIn" Val="simulation"/>
         </FileInfo>
       </File>
-      <File Path="$PSRCDIR/ppu_pceg_tb.vhdl">
-        <FileInfo>
-          <Attr Name="AutoDisabled" Val="1"/>
+      <File Path="$PSRCDIR/ppu_pceg_tb.vhd">
+        <FileInfo SFType="VHDL2008">
           <Attr Name="UsedIn" Val="synthesis"/>
           <Attr Name="UsedIn" Val="simulation"/>
         </FileInfo>
@@ -160,14 +226,49 @@
       <File Path="$PSRCDIR/apu_note_to_frequency_tb.vhd">
         <FileInfo>
           <Attr Name="UserDisabled" Val="1"/>
-          <Attr Name="AutoDisabled" Val="1"/>
+          <Attr Name="UsedIn" Val="synthesis"/>
+          <Attr Name="UsedIn" Val="simulation"/>
+        </FileInfo>
+      </File>
+      <File Path="$PSRCDIR/er_ram_mod_tb.vhd">
+        <FileInfo SFType="VHDL2008">
+          <Attr Name="UsedIn" Val="synthesis"/>
+          <Attr Name="UsedIn" Val="simulation"/>
+        </FileInfo>
+      </File>
+      <File Path="$PSRCDIR/er_ram_tb.vhd">
+        <FileInfo SFType="VHDL2008">
+          <Attr Name="UsedIn" Val="synthesis"/>
+          <Attr Name="UsedIn" Val="simulation"/>
+        </FileInfo>
+      </File>
+      <File Path="$PSRCDIR/ppu_aux_tb.vhd">
+        <FileInfo>
+          <Attr Name="UsedIn" Val="synthesis"/>
+          <Attr Name="UsedIn" Val="simulation"/>
+        </FileInfo>
+      </File>
+      <File Path="$PSRCDIR/ppu_sprite_bg_tb.vhd">
+        <FileInfo SFType="VHDL2008">
+          <Attr Name="UsedIn" Val="synthesis"/>
+          <Attr Name="UsedIn" Val="simulation"/>
+        </FileInfo>
+      </File>
+      <File Path="$PSRCDIR/ppu_sprite_transform_tb.vhd">
+        <FileInfo>
+          <Attr Name="UsedIn" Val="synthesis"/>
+          <Attr Name="UsedIn" Val="simulation"/>
+        </FileInfo>
+      </File>
+      <File Path="$PSRCDIR/ppu_sprite_fg_tb.vhd">
+        <FileInfo SFType="VHDL2008">
           <Attr Name="UsedIn" Val="synthesis"/>
           <Attr Name="UsedIn" Val="simulation"/>
         </FileInfo>
       </File>
       <Config>
         <Option Name="DesignMode" Val="RTL"/>
-        <Option Name="TopModule" Val="ppu_addr_dec_tb"/>
+        <Option Name="TopModule" Val="ppu_sprite_fg_tb"/>
         <Option Name="TopLib" Val="xil_defaultlib"/>
         <Option Name="TransportPathDelay" Val="0"/>
         <Option Name="TransportIntDelay" Val="0"/>
@@ -177,10 +278,19 @@
         <Option Name="PamSignalDriverFile" Val="xil_bypass_driver"/>
         <Option Name="PamPseudoTop" Val="pseudo_tb"/>
         <Option Name="SrcSet" Val="sources_1"/>
+        <Option Name="NLNetlistMode" Val="funcsim"/>
       </Config>
     </FileSet>
     <FileSet Name="utils_1" Type="Utils" RelSrcDir="$PSRCDIR/utils_1" RelGenDir="$PGENDIR/utils_1">
       <Filter Type="Utils"/>
+      <File Path="$PSRCDIR/utils_1/imports/synth_1/ppu.dcp">
+        <FileInfo>
+          <Attr Name="UsedIn" Val="synthesis"/>
+          <Attr Name="UsedIn" Val="implementation"/>
+          <Attr Name="UsedInSteps" Val="synth_1"/>
+          <Attr Name="AutoDcp" Val="1"/>
+        </FileInfo>
+      </File>
       <Config>
         <Option Name="TopAutoSet" Val="TRUE"/>
       </Config>
@@ -234,11 +344,12 @@
     </Simulator>
   </Simulators>
   <Runs Version="1" Minor="19">
-    <Run Id="synth_1" Type="Ft3:Synth" SrcSet="sources_1" Part="xc7a35tcpg236-1" ConstrsSet="constrs_1" Description="Vivado Synthesis Defaults" AutoIncrementalCheckpoint="true" WriteIncrSynthDcp="false" State="current" IncludeInArchive="true" IsChild="false" AutoIncrementalDir="$PSRCDIR/utils_1/imports/synth_1" AutoRQSDir="$PSRCDIR/utils_1/imports/synth_1">
+    <Run Id="synth_1" Type="Ft3:Synth" SrcSet="sources_1" Part="xc7a35tcpg236-1" ConstrsSet="constrs_1" Description="Vivado Synthesis Defaults" AutoIncrementalCheckpoint="true" IncrementalCheckpoint="$PSRCDIR/utils_1/imports/synth_1/ppu.dcp" WriteIncrSynthDcp="false" State="current" Dir="$PRUNDIR/synth_1" IncludeInArchive="true" IsChild="false" AutoIncrementalDir="$PSRCDIR/utils_1/imports/synth_1" AutoRQSDir="$PSRCDIR/utils_1/imports/synth_1">
       <Strategy Version="1" Minor="2">
         <StratHandle Name="Vivado Synthesis Defaults" Flow="Vivado Synthesis 2022"/>
         <Step Id="synth_design"/>
       </Strategy>
+      <GeneratedRun Dir="$PRUNDIR" File="gen_run.xml"/>
       <ReportStrategy Name="Vivado Synthesis Default Reports" Flow="Vivado Synthesis 2022"/>
       <Report Name="ROUTE_DESIGN.REPORT_METHODOLOGY" Enabled="1"/>
       <RQSFiles/>
diff --git a/docs/architecture.md b/docs/architecture.md
index a60e0da..0c6fea7 100644
--- a/docs/architecture.md
+++ b/docs/architecture.md
@@ -134,6 +134,12 @@ Notable differences:
   
   Our game doesn't need this capability for any visual effects. Leaving this
   feature out will lead to a simpler hardware design
+- Sprites are positioned relative to the viewport, not the background layer
+  
+  This leads to a simpler hardware architecture for the foreground sprite
+  rendering component. Since the CPU is already likely to reposition all
+  foreground sprites on every frame, the position calculation is moved to
+  hardware to software.
 
 ## Hardware design schematics
 
@@ -227,16 +233,17 @@ Important notes:
 - The PPU's memory bus has 16-bit addresses and 16-bit words.
 - Some memory regions use physical word sizes smaller than 16-bits, so
   "unneeded" bits will be discarded by the PPU.
-- All "fields" or words containing multiple bit strings representing different
-  pieces of information are ordered from MSB to LSB.
+- Apparent size means the amount of addresses in a given memory region. As
+  mentioned earlier, the exact word sizes of a memory area can vary, though
+  this is not visible to the CPU as all data is presented as 16-bit words.
 
-|Address offset|Size (16-bit words)|Alias|Description|
+|Address offset|Apparent size|Alias|Description|
 |-|-|-|-|
-|`0x0000`|`0xc000`|TMM  |[tilemap memory][TMM]|
-|`0xc000`|`0x04b0`|BAM  |[background attribute memory][BAM]|
-|`0xc800`|`0x0100`|FAM  |[foreground attribute memory][FAM]|
-|`0xcc00`|`0x0040`|PAL  |[palettes][PAL]|
-|`0xce00`|`0x0002`|AUX  |[auxiliary memory][AUX]|
+|`0x0000`|`0xd000`|TMM  |[tilemap memory][TMM]|
+|`0xd000`|`0x04b0`|BAM  |[background attribute memory][BAM]|
+|`0xd800`|`0x0100`|FAM  |[foreground attribute memory][FAM]|
+|`0xdc00`|`0x0040`|PAL  |[palettes][PAL]|
+|`0xde00`|`0x0002`|AUX  |[auxiliary memory][AUX]|
 
 This table contains the "official" PPU register offsets and sizes. Due to the
 way the address decoder works, some of these memory regions might be duplicated
@@ -247,24 +254,44 @@ there is no address validity checking.
 [TMM]: #tilemap-memory
 ### Tilemap memory
 
-- Each sprite takes up 768 bits spread across 48 16-bit words
-- Sprites and pixels are stored adjacently in memory without padding
-- Pixel order is from top-left to bottom-right in (English) reading order.
+- Each sprite takes up 768 bits spread across 52 15-bit words (with one
+  discarded padding bit per word)
+- Pixel index order is from top-left to bottom-right in (English) reading
+  order.
+- Bits `14 downto 3` of the byte with the highest address for a given tile are
+  not used
+- To calculate TMM address $a$ for any given pixel $p$ of tile with index $t$,
+  compute $a=52*t+\left\lfloor\frac{p}{5}\right\rfloor$
+
+Word format:
+
+|Range (VHDL)|Description|
+|-|-|
+|`15`|(discarded)|
+|`14 downto 12`|pixel $n+4$|
+|`11 downto 9`|pixel $n+3$|
+|`8 downto 6`|pixel $n+2$|
+|`5 downto 3`|pixel $n+1$|
+|`2 downto 0`|pixel $n+0$|
+
 
 [BAM]: #background-attribute-memory
 ### Background attribute memory
 
 - 15-bit words (MSB discarded in hardware)
-- Address indicates which background sprite is currently targeted in reading order  
-  e.g. $\textrm{addr} = c000_{\textrm{hex}} + x + y*w$ where $x$ and $y$ are the background tile, and $w$ is the amount of horizontal tiles fit on the background layer (40)
+- Address indicates which background sprite is currently targeted in reading
+  order  
+  e.g. $\textrm{addr} = c000_{\textrm{hex}} + x + y*w$ where $x$ and $y$
+  are the background tile, and $w$ is the amount of horizontal tiles fit on the
+  background layer (40)
 
 Word format:
 
 |Range (VHDL)|Description|
 |-|-|
-|`15`|Flip horizontally|
-|`14`|Flip vertically|
-|`13`|(unused)|
+|`15`|(discarded)|
+|`14`|Flip horizontally|
+|`13`|Flip vertically|
 |`12 downto 10`|Palette index for tile|
 |`9 downto 0`|Tilemap index|
 
diff --git a/style.md b/style.md
index 7e6b9b6..3fe912b 100644
--- a/style.md
+++ b/style.md
@@ -30,12 +30,14 @@ before formatting as a failsafe.
 - custom typedefs are prefixed with `hh_` and suffixed with `_t` (e.g. `hh_bam_tile_t`)
 - library hooks that need specific symbol names are exempt from the naming
   conventions (e.g. `main` or `HAL_UART_MspInit`)
+- names are always in English
 
 ## others
 
 - document **how to use** code using doxygen-style comments in headers
 - document **what code is doing** using inline comments (where applicable)
 - don't write redundant comments (e.g. `int c = a + b; // add a and b`)
+- comments are always in English
 
 ### markdown
 
@@ -50,4 +52,31 @@ before formatting as a failsafe.
 - use lower case keywords
 - testbench name is the component name with `_tb` as suffix
 - vhdl filename is the same as the component name
-
+- vhdl files should end in the `.vhd` file extension, not `.vhdl`
+- use spaces around the colon used for setting the type of signal definitions
+- do not mix uppercase and lowercase in entity/component/port/signal names
+- remove the default vivado file headers (large comment blocks with file info)
+- add a comment to the entity definition describing what the entity does
+- library import names should be lowercase
+- with the exception of off by one shifts, absolutely NO magic numbers are
+  allowed. use existing constants if possible, or create new ones in a consts
+  file instead of using magic numbers.
+- entities/components without a generic map should put the opening `port (` on
+  the same line as the `entity ... is ` line
+- entities/components with a generic map should be formatted like this:
+  ```
+  entity ... is
+    generic map(
+      NAME : type := default;
+      NAME : type := default)
+    port map(
+      NAME : in type;
+      NAME : out type);
+  end ...;
+  ```
+- port/generic maps with only one signal should be condensed into a single line
+- all library declarations should be grouped together at the top of the file
+- all `use` directives should be grouped together below the library
+  declarations
+- use a space before and after the comment syntax, e.g. `variable x : integer
+  := 0; -- comment here`
diff --git a/test/sdl2/.gitignore b/test/sdl2/.gitignore
new file mode 100644
index 0000000..f0c9b81
--- /dev/null
+++ b/test/sdl2/.gitignore
@@ -0,0 +1,2 @@
+*.o
+main
diff --git a/test/sdl2/main.c b/test/sdl2/main.c
new file mode 100644
index 0000000..beddc3f
--- /dev/null
+++ b/test/sdl2/main.c
@@ -0,0 +1,48 @@
+#include <stdlib.h>
+#include <stdbool.h>
+#include <math.h>
+#include <SDL2/SDL.h>
+
+#define UPSCALE_FACTOR 3
+#define WIN_HEIGHT 240
+#define WIN_WIDTH 320
+#define FPS 60
+
+static void pixel(SDL_Renderer* r, unsigned px, unsigned py, unsigned cr, unsigned cg, unsigned cb) {
+		SDL_SetRenderDrawColor(r, cr, cg, cb, 255);
+		SDL_RenderFillRect(r, &(SDL_Rect) {.x = px * UPSCALE_FACTOR, .y = py * UPSCALE_FACTOR, .w = UPSCALE_FACTOR, .h = UPSCALE_FACTOR});
+}
+
+int main() {
+	SDL_Init(SDL_INIT_VIDEO | SDL_INIT_EVENTS);
+	SDL_Window *window = SDL_CreateWindow("sdl2 test", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, WIN_WIDTH * UPSCALE_FACTOR, WIN_HEIGHT * UPSCALE_FACTOR, SDL_WINDOW_SHOWN);
+	SDL_Renderer *renderer = SDL_CreateRenderer(window, -1, SDL_RENDERER_ACCELERATED);
+
+	SDL_Event e;
+	unsigned long frame = 0;
+	while (true) {
+		uint32_t start = SDL_GetTicks();
+		frame++;
+		while (SDL_PollEvent(&e)) if (e.type == SDL_QUIT) exit(0);
+		
+		SDL_RenderClear(renderer);
+
+		for (unsigned i = 0; i < WIN_WIDTH; i++) {
+			for (unsigned j = 0; j < WIN_HEIGHT; j++) {
+				pixel(renderer, i, j, (unsigned)(sqrt(i * 20) + frame) % 255, (i * j + frame) % 255, (j * 20) % 255);
+			}
+		}
+
+		SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255);
+		SDL_RenderPresent(renderer);
+
+		uint32_t end = SDL_GetTicks();
+		int wait_for = 1000 / FPS - (end - start);
+		if (wait_for > 0) SDL_Delay(wait_for);
+	}
+
+	SDL_DestroyRenderer(renderer);
+	SDL_DestroyWindow(window);
+	SDL_Quit();
+	return 0;
+}
diff --git a/test/sdl2/makefile b/test/sdl2/makefile
new file mode 100644
index 0000000..4c26dc3
--- /dev/null
+++ b/test/sdl2/makefile
@@ -0,0 +1,18 @@
+CC = gcc
+LD = gcc
+RM = rm -f
+TARGET = main
+LFLAGS += -lSDL2 -lm
+OBJS += main.o
+
+all: $(TARGET)
+
+%.o: %.c
+	$(CC) -c $(CFLAGS) $< -o $@
+
+$(TARGET): $(OBJS)
+	$(LD) $^ $(LFLAGS) -o $@
+
+clean:
+	$(RM) $(TARGET) $(OBJS)
+
diff --git a/test/sdl2/readme.md b/test/sdl2/readme.md
new file mode 100644
index 0000000..940e315
--- /dev/null
+++ b/test/sdl2/readme.md
@@ -0,0 +1,6 @@
+# sdl2 test
+
+this is a simple POC that makes a window to draw PPU graphics to using SDL2.
+this code will be moved to the stm32/ppu directory, and the stm32's makefile
+will be edited to include a sim target for building the game for desktop
+debugging.