hey guys , i tried to develop a square on a vga monitor which is lcd but the program has some errors . no syntax error but simulation results and implementaion is not correct . the code is -


----------------------------------------------------------------------------------
-- Company:
-- Engineer:
--
-- Create Date: 22:38:18 01/04/2012
-- Design Name:
-- Module Name: display - Behavioral
-- Project Name:
-- Target Devices:
-- Tool versions:
-- Description:
--
-- Dependencies:
--
-- Revision:
-- Revision 0.01 - File Created
-- Additional Comments:
--
----------------------------------------------------------------------------------
library IEEE;
use IEEE.STD_LOGIC_1164.ALL;

library IEEE;
use IEEE.std_logic_signed.ALL;

-- Uncomment the following library declaration if using
-- arithmetic functions with Signed or Unsigned values
--use IEEE.NUMERIC_STD.ALL;

-- Uncomment the following library declaration if instantiating
-- any Xilinx primitives in this code.
--library UNISIM;
--use UNISIM.VComponents.all;

entity display is
Port ( hs_out : out STD_LOGIC;
vs_out : out STD_LOGIC;
red_out : out STD_LOGIC;
green_out : out STD_LOGIC;
blue_out : out STD_LOGIC;
clk50 , rst : in STD_LOGIC);
end display;

architecture Behavioral of display is
signal horizontal_counter : std_logic_vector (7 downto 0);
signal vertical_counter : std_logic_vector (7 downto 0);
signal clk_counter : std_logic_vector ( 9 downto 0 ) := "0000000000" ;
signal clk35 : std_logic ;
begin
-- generate a 50khz clock
process (clk50 , rst)
begin
if ( rst = '1' ) then
if clk50'event and clk50='1' then
clk_counter end if;
if ( clk_counter = "111111111" ) then
if ( clk35 = '0' ) then
clk35 else
clk35 end if ;
end if ;
else
clk_counter end if ;
end process;
-- checked
process (clk35)
begin
if clk35'event and clk35 = '1' then
if (horizontal_counter >= "00000000" ) -- 144
and (horizontal_counter and (vertical_counter >= "00000000" ) -- 39
and (vertical_counter then
red_out green_out blue_out else
red_out green_out blue_out end if;
if (horizontal_counter > "00000000" )
and (horizontal_counter then
hs_out else
hs_out end if;
if (vertical_counter > "00000000" )
and (vertical_counter then
vs_out else
vs_out end if;
horizontal_counter if (horizontal_counter="10010000") then
vertical_counter horizontal_counter end if;
if (vertical_counter="10000101") then
vertical_counter end if;
end if;
end process;


end Behavioral;

Are you looking for help with using one of the opencores cores? If so, which core?

Well if you want a resolution 640x480 60hz you should use 25 MHz as a clock
If you are looking for a block that generate the needed signals use the one given by Digilent at:
http://www.digilentinc.com/Products/Detail.cfm?NavPath=2,400,792&Prod=S3EBOARD ---> VGA controller reference design

I hope it will help you