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Revision 441

Added by markw over 9 years ago

register output data

View differences:

sram_mux.vhd
signal sram_drive_data_next : std_logic;
signal sram_drive_data_reg : std_logic;
signal sram_write_data_next : std_logic_vector(7 downto 0);
signal sram_write_data_reg : std_logic_vector(7 downto 0);
signal tick_next : std_logic;
signal tick_reg : std_logic;
......
-- Back to back writes from 65816?
process(veronica_address, veronica_write_data, veronica_w_n, veronica_sram_select,
atari_bus_request, atari_address,atari_write_data, atari_w_n, atari_sram_select, tick_fast_reg)
atari_bus_request, atari_address,atari_write_data, atari_w_n, atari_sram_select, tick_fast_reg,
sram_we_n_next)
begin
sram_addr <= (others=>'0');
sram_data_out <= (others=>'0');
sram_write_data_next <= (others=>'0');
sram_drive_data_next <= '0';
if (atari_bus_request='1') then
sram_addr(16 downto 0) <= atari_address;
sram_data_out <= atari_write_data;
sram_write_data_next <= atari_write_data;
sram_we_n_next <= (atari_w_n or not(atari_sram_select) or tick_fast_reg(6));
else
sram_addr(16 downto 0) <= veronica_address;
sram_data_out <= veronica_write_data;
sram_write_data_next <= veronica_write_data;
sram_we_n_next <= (veronica_w_n or not(veronica_sram_select) or tick_fast_reg(6));
end if;
......
tick_last_fast_reg <= '0';
sram_we_n_reg <= '1';
sram_drive_data_reg <= '0';
sram_write_data_reg <= (others=>'0');
elsif (clk7x'event and clk7x='1') then
tick_fast_reg <= tick_fast_next;
tick_last_fast_reg <= tick_last_fast_next;
sram_we_n_reg <= sram_we_n_next;
sram_drive_data_reg <= sram_drive_data_next;
sram_write_data_reg <= sram_write_data_next;
end if;
end process;
tick_last_fast_next <= tick_reg;
......
sram_we_n <= sram_we_n_reg;
sram_drive_data <= sram_drive_data_reg;
sram_data_out <= sram_write_data_reg;
end vhdl;

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