diff --git a/sys/sys_top.v b/sys/sys_top.v
index d0e7a0c..1d63de1 100644
--- a/sys/sys_top.v
+++ b/sys/sys_top.v
@@ -437,6 +437,35 @@ wire         vbuf_read;
 wire [127:0] vbuf_writedata;
 wire  [15:0] vbuf_byteenable;
 wire         vbuf_write;
+reg  [5:0]  FB_FMTX;
+
+/*
+
+OLD_FORMAT                NEW FORMAT
+  "000" 16bits 1555 RGB => 01100
+  "001" 24bpp       RGB => 00101
+  "010" 32bpp       RGB => 00110
+  "011" 16bits 565  RGB => 00100
+  "100" 16bits 1555 BGR => 11100
+  "101" 24bpp       BGR => 10101
+  "110" 32bpp       BGR => 10110
+  "111" 16bits 565  BGR => 10100
+          8bits palette => x0011
+*/
+
+always @(posedge clk_sys) begin
+   FB_FMTX <=6'b010101;
+	case(FB_FMT[2:0])
+		0: FB_FMTX <=6'b001100;
+		1: FB_FMTX <=6'b000101;
+		2: FB_FMTX <=6'b000110;
+		3: FB_FMTX <=6'b000100;
+		4: FB_FMTX <=6'b011100;
+		5: FB_FMTX <=6'b010101;
+		6: FB_FMTX <=6'b010110;
+		7: FB_FMTX <=6'b010100;
+	endcase
+end
 
 ascal 
 #(
@@ -496,7 +525,7 @@ ascal
 	.o_fb_ena         (FB_EN),
 	.o_fb_hsize       (FB_WIDTH),
 	.o_fb_vsize       (FB_HEIGHT),
-	.o_fb_format      (FB_FMT),
+	.o_fb_format      (FB_FMTX),
 	.o_fb_base        (FB_BASE),
 
 	.avl_clk          (clk_100m),