diff --git a/lib/emac/src/emac_top_jb.vhd b/lib/emac/src/emac_top_jb.vhd
index 17b3bff..17d6537 100644
--- a/lib/emac/src/emac_top_jb.vhd
+++ b/lib/emac/src/emac_top_jb.vhd
@@ -123,9 +123,7 @@ registers_write:
 					tx_ctrl_in.tx_size			<= DAT_I(15 downto 0);
 					
 				-- 0x0010
-				when "0100" =>
-					tx_din_vld					<= '1';
-					tx_din						<= DAT_I;
+				-- Gap
 					
 				-- 0x0014
 				-- Gap
@@ -142,7 +140,13 @@ registers_write:
 					rx_ctrl_in.mac_addr(4)		<= DAT_I(31 downto 24);
 					rx_ctrl_in.mac_addr(5)		<= DAT_I(23 downto 16);
 
-				when others => null;
+				-- 0x0020 .. 0x003C
+				-- Window for TX-Data (8 words)
+				-- For cached burst access, this must be greater or equal to D-Cache line size
+				when others =>
+					tx_din_vld					<= '1';
+					tx_din						<= DAT_I;
+				
 				end case;
 			end if;	
 		end if;	
@@ -195,8 +199,7 @@ registers_read:
 					DAT_O		<= X"0000" & tx_ctrl_out.tx_size;
 
 				-- 0x0010
-				when "0100" =>
-					rx_ctrl_in.pkt_read_en	<= '1';
+				-- Gap
 						
 				-- 0x0014
 				-- Gap
@@ -211,7 +214,12 @@ registers_read:
 					ACK_O		<= '1';
 					DAT_O		<= rx_ctrl_in.mac_addr(4) & rx_ctrl_in.mac_addr(5) & X"0000";
 				
-				when others => null;
+				-- 0x0020 .. 0x003C
+				-- Window for RX-Data (8 words)
+				-- For cached burst access, this must be greater or equal to D-Cache line size
+				when others =>
+					rx_ctrl_in.pkt_read_en	<= '1';
+					
 				end case;
 			end if;
 		end if;