X-Git-Url: http://git.joshuawise.com/fpgaboy.git/blobdiff_plain/ff7fd7f2e78ed70833e58cecc316d5c8d6603349..dadf7990cbca24581bbb3c036df717dd59bdea41:/System.v

diff --git a/System.v b/System.v
index 033e4b1..8bc14e9 100644
--- a/System.v
+++ b/System.v
@@ -21,19 +21,22 @@ module InternalRAM(
 	input clk,
 	input wr, rd);
 	
+	// synthesis attribute ram_style of reg is block
 	reg [7:0] ram [8191:0];
 	
-	wire decode = ({0,address} >= 17'hC000) && ({0,address} < 17'hFE00);
+	wire decode = address[15:13] == 3'b110;
 	reg [7:0] odata;
 	wire idata = data;
 	assign data = (rd && decode) ? odata : 8'bzzzzzzzz;
 	
 	always @(negedge clk)
 	begin
-		if (decode && rd)
+		if (decode)	// This has to go this way. The only way XST knows how to do
+		begin				// block ram is chip select, write enable, and always
+			if (wr)		// reading. "else if rd" does not cut it ...
+				ram[address[12:0]] <= data;
 			odata <= ram[address[12:0]];
-		else if (decode && wr)
-			ram[address[12:0]] <= data;
+		end
 	end
 endmodule