diff --git a/rtl/ide_disk.v b/rtl/ide_disk.v
index 719f7de..715977f 100644
--- a/rtl/ide_disk.v
+++ b/rtl/ide_disk.v
@@ -398,8 +398,9 @@ module ide_disk(clk, reset,
 	       ata_wr = 1;
 	       ata_addr = ATA_DATA;
 	       ata_in = {4'b0, buffer_in_hold};
+`ifdef debug
 	       $display("ide_disk: write1, %o", buffer_in_hold);
-	       
+`endif	       
 	       if (ata_done)
 		 begin
 		    if (wc == 8'h00)
diff --git a/rtl/pdp8.v b/rtl/pdp8.v
index f397a49..9be5d9b 100644
--- a/rtl/pdp8.v
+++ b/rtl/pdp8.v
@@ -668,11 +668,13 @@ module pdp8(clk, reset, initial_pc, pc_out, ac_out,
 	      if (interrupt && interrupt_enable &&
 		  !interrupt_inhibit && !interrupt_cycle)
 		begin
+`ifdef debug
 		   if (1)
 		   $display("xxx interrupt, pc %o; %b %b %b; %b %b",
 			    pc,
 			    interrupt, interrupt_enable, interrupt_cycle,
 			    interrupt_inhibit, interrupt_inhibit_delay);
+`endif
 		   interrupt_cycle <= 1;
 		   interrupt <= 0;
 		   interrupt_enable <= 0;
@@ -692,8 +694,10 @@ module pdp8(clk, reset, initial_pc, pc_out, ac_out,
 		begin
 		   interrupt_cycle <= 0;
 
+`ifdef debug
 		   if (0)
 		   $display("cpu: read ram [%o] -> %o", ram_addr, ram_data_in);
+`endif
 		   
 		   mb <= ram_data_in;
 		   ir <= ram_data_in[11:9];
@@ -761,7 +765,9 @@ module pdp8(clk, reset, initial_pc, pc_out, ac_out,
 	      if (iot && UF)
 		begin
 		   UI <= 1;
-$display("user iot: set UI");
+`ifdef debug
+		   $display("user iot: set UI");
+`endif
 		end
 
 	      if (iot && ~UF)
@@ -962,7 +968,9 @@ $display("user iot: set UI");
 	 //
 	 D0:
 	   begin
+`ifdef debug
 	      if (0) $display("read ram [%o] -> %o", ram_addr, ram_data_in);
+`endif
 	      mb <= ram_data_in;
 	   end
 
@@ -975,9 +983,11 @@ $display("user iot: set UI");
 
 	 D2:
 	   begin
+`ifdef debug
 	      // write ram
 	      if (ram_wr)
 	      if (0) $display("write ram [%o] <- %o", ram_addr, ram_data_out);
+`endif
 	   end
 	 
 	 D3:
@@ -989,7 +999,9 @@ $display("user iot: set UI");
 	 //
 	 E0:
 	   begin
+`ifdef debug
 	      if (0) $display("read ram [%o] -> %o", ram_addr, ram_data_in);
+`endif
 	      mb <= ram_data_in;
 	   end
 
@@ -1012,9 +1024,11 @@ $display("user iot: set UI");
 	 E2:
 	   begin
 	      // write ram
+`ifdef debug
 	      if (ram_wr)
 	      if (0) $display("write ram [%o] <- %o (pc %o)",
 				ram_addr, ram_data_out, pc);
+`endif
 	   end
 	 
 	 E3:
diff --git a/rtl/pdp8_tt.v b/rtl/pdp8_tt.v
index a118f36..caf2f6e 100644
--- a/rtl/pdp8_tt.v
+++ b/rtl/pdp8_tt.v
@@ -249,13 +249,17 @@ tx_int <= 1'b0;
 	    begin
 	       if (assert_rx_int && ~rx_int)
 		 begin
-$display("xxx set rx_int");
+`ifdef debug
+		    $display("xxx set rx_int");
+`endif
 		    rx_int <= 1;
 		 end
 
 	       if (assert_tx_int && ~tx_int)
 		 begin
-$display("xxx set tx_int");
+`ifdef debug
+		    $display("xxx set tx_int");
+`endif
 		    tx_int <= 1;
 		 end
 
diff --git a/rtl/top.v b/rtl/top.v
index 6b63b07..86450df 100644
--- a/rtl/top.v
+++ b/rtl/top.v
@@ -47,10 +47,13 @@ module top(rs232_txd, rs232_rxd,
    output [1:0]  ide_cs;
    output [2:0]  ide_da;
 
+   wire [15:0] 	 ide_data_in;
+   wire [15:0] 	 ide_data_out;
+
    // -----------------------------------------------------------------
 
 `ifndef sim_time
- `define slower
+// `define slower
 `endif
 
 `ifdef slower
@@ -177,10 +180,14 @@ module top(rs232_txd, rs232_rxd,
 	      .ide_diow(ide_diow),
 	      .ide_cs(ide_cs),
 	      .ide_da(ide_da),
-	      .ide_data_bus(ide_data_bus),
+	      .ide_data_in(ide_data_in),
+	      .ide_data_out(ide_data_out),
 	      .rs232_in(rs232_rxd),
 	      .rs232_out(rs232_txd));
 
+   assign ide_data_bus = ~ide_diow ? ide_data_out : 16'bz;
+   assign ide_data_in = ide_data_bus;
+   
    pdp8_ram ram(.clk(clk),
 		.reset(reset), 
 		.addr(ram_addr),