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[/] [System09/] [tags/] [LinuxPort/] [src/] [Flex9/] [flex_ram_vhd] - Rev 106
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--
-- Flex9 O/S Initialised 8KByte RAM
--
-- v1.0 - 22 December 2006 - John Kent
-- v1.1 - 1 February 2008 - David Burnette
-- reworked to use autogenerated block ram utility
library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.STD_LOGIC_ARITH.ALL;
library unisim;
use unisim.vcomponents.all;
entity flex_ram is
Port (
clk : in std_logic;
rst : in std_logic;
cs : in std_logic;
rw : in std_logic;
addr : in std_logic_vector (12 downto 0);
rdata : out std_logic_vector (7 downto 0);
wdata : in std_logic_vector (7 downto 0)
);
end flex_ram;
architecture rtl of flex_ram is
signal we : std_logic;
signal cs0 : std_logic;
signal cs1 : std_logic;
signal cs2 : std_logic;
signal cs3 : std_logic;
signal dp0 : std_logic;
signal dp1 : std_logic;
signal dp2 : std_logic;
signal dp3 : std_logic;
signal rdata0 : std_logic_vector(7 downto 0);
signal rdata1 : std_logic_vector(7 downto 0);
signal rdata2 : std_logic_vector(7 downto 0);
signal rdata3 : std_logic_vector(7 downto 0);
component FLEX9_C000
Port (
clk : in std_logic;
rst : in std_logic;
cs : in std_logic;
rw : in std_logic;
addr : in std_logic_vector (10 downto 0);
rdata : out std_logic_vector (7 downto 0);
wdata : in std_logic_vector (7 downto 0)
);
end component;
component FLEX9_C800
Port (
clk : in std_logic;
rst : in std_logic;
cs : in std_logic;
rw : in std_logic;
addr : in std_logic_vector (10 downto 0);
rdata : out std_logic_vector (7 downto 0);
wdata : in std_logic_vector (7 downto 0)
);
end component;
component FLEX9_D000
Port (
clk : in std_logic;
rst : in std_logic;
cs : in std_logic;
rw : in std_logic;
addr : in std_logic_vector (10 downto 0);
rdata : out std_logic_vector (7 downto 0);
wdata : in std_logic_vector (7 downto 0)
);
end component;
component FLEX9_D800
Port (
clk : in std_logic;
rst : in std_logic;
cs : in std_logic;
rw : in std_logic;
addr : in std_logic_vector (10 downto 0);
rdata : out std_logic_vector (7 downto 0);
wdata : in std_logic_vector (7 downto 0)
);
end component;
begin
addr_c000 : FLEX9_C000 port map (
clk => clk,
rst => rst,
cs => cs0,
rw => rw,
addr => addr(10 downto 0),
wdata => wdata,
rdata => rdata0
);
addr_c800 : FLEX9_C800 port map (
clk => clk,
rst => rst,
cs => cs1,
rw => rw,
addr => addr(10 downto 0),
wdata => wdata,
rdata => rdata1
);
addr_d000 : FLEX9_D000 port map (
clk => clk,
rst => rst,
cs => cs2,
rw => rw,
addr => addr(10 downto 0),
wdata => wdata,
rdata => rdata2
);
addr_d800 : FLEX9_D800 port map (
clk => clk,
rst => rst,
cs => cs3,
rw => rw,
addr => addr(10 downto 0),
wdata => wdata,
rdata => rdata3
);
my_flex : process ( rw, addr, cs, rdata0, rdata1, rdata2, rdata3 )
begin
we <= not rw;
case addr(12 downto 11) is
when "00" =>
cs0 <= cs;
cs1 <= '0';
cs2 <= '0';
cs3 <= '0';
rdata <= rdata0;
when "01" =>
cs0 <= '0';
cs1 <= cs;
cs2 <= '0';
cs3 <= '0';
rdata <= rdata1;
when "10" =>
cs0 <= '0';
cs1 <= '0';
cs2 <= cs;
cs3 <= '0';
rdata <= rdata2;
when "11" =>
cs0 <= '0';
cs1 <= '0';
cs2 <= '0';
cs3 <= cs;
rdata <= rdata3;
when others =>
null;
end case;
end process;
end architecture rtl;
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