Scramble HW: use ARC files to select the game

common/mist/mist.vhd

@@ -32,6 +32,7 @@ port (
 	scandoubler_disable : out std_logic;
 	ypbpr             : out std_logic;
 	no_csync          : out std_logic;
+	core_mod          : out std_logic_vector(6 downto 0);
 
 	sd_lba            : in  std_logic_vector(31 downto 0) := (others => '0');
 	sd_rd             : in  std_logic := '0';

common/mist/user_io.v

@@ -46,6 +46,7 @@ module user_io #(parameter STRLEN=0, parameter PS2DIV=100, parameter ROM_DIRECT_
 	output              ypbpr,
 	output              no_csync,
 	output reg   [31:0] status,
+	output reg    [6:0] core_mod, // core variant, sent before the config string is requested
 
 	// connection to sd card emulation
 	input        [31:0] sd_lba,
@@ -479,7 +480,10 @@ always @(posedge clk_sys) begin
 				// status, 32bit version
 				8'h1e: if(abyte_cnt<5) status[(abyte_cnt-1)<<3 +:8] <= spi_byte_in;
 
-				endcase
+				// core variant
+				8'h21: core_mod <= spi_byte_in[6:0];
+
+			endcase
 		end
 	end
 end