diff --git a/rtl/ide_disk.v b/rtl/ide_disk.v
index 2af26f7..9add92c 100644
--- a/rtl/ide_disk.v
+++ b/rtl/ide_disk.v
@@ -173,7 +173,7 @@ module ide_disk(clk, reset,
    always @(ide_state or ide_write_req or ide_read_req or
 	    lba or offset or wc or start or
             ata_done or ata_out or
-	    buffer_in)
+	    buffer_in or buffer_in_hold)
      begin
 	ide_state_next = ide_state;
 
diff --git a/rtl/pdp8.v b/rtl/pdp8.v
index 0ad63c5..582b40d 100644
--- a/rtl/pdp8.v
+++ b/rtl/pdp8.v
@@ -594,7 +594,10 @@ module pdp8(clk, reset, initial_pc, pc_out, ac_out,
 
 				3'b101:					// SINT
 				  begin
-$display("SINT: UI %b, state %b", UI, state);
+`ifdef debug
+				     $display("SINT: UI %b, state %b",
+					      UI, state);
+`endif
 				     if (UI)
 				       interrupt_skip = 1;
 				  end
@@ -802,7 +805,10 @@ $display("user iot: set UI");
 
 				3'b101:					// SINT
 				  begin
-$display("SINT: UI %b, state %b", UI, state);
+`ifdef debug
+				     $display("SINT: UI %b, state %b",
+					      UI, state);
+`endif
 //				     if (UI)
 //				       interrupt_skip = 1;
 				  end
diff --git a/rtl/pdp8_io.v b/rtl/pdp8_io.v
index 433a5fc..0eee85d 100644
--- a/rtl/pdp8_io.v
+++ b/rtl/pdp8_io.v
@@ -131,12 +131,12 @@ module pdp8_io(clk, brgclk, reset, iot, state, mb,
 			 rf_io_selected ? rf_io_data_avail :
 			 1'b0;
 
-//`ifdef debug_ints
+`ifdef debug
    always @(*)
      if (io_interrupt)
        $display("io: io_interrupt: %b %b %b", 
 		kw_io_interrupt, tt_io_interrupt, rf_io_interrupt);
-//`endif
+`endif
    
    assign io_interrupt = kw_io_interrupt |
 			 tt_io_interrupt |
diff --git a/rtl/pdp8_rf.v b/rtl/pdp8_rf.v
index 1c7d05a..56e23ba 100644
--- a/rtl/pdp8_rf.v
+++ b/rtl/pdp8_rf.v
@@ -1117,7 +1117,9 @@ module pdp8_rf(clk, reset, iot, state, mb,
        else
 	 if (set_buffer_addr)
 	   begin
+`ifdef debug
 	      $display("set-buffer-addr; clean, disk-addr %o, %t", disk_addr[19:8], $time);
+`endif
 	      buffer_dirty <= 1'b0;
 	      buffer_disk_addr[19:8] <= disk_addr[19:8];
 	   end
diff --git a/rtl/pdp8_tt.v b/rtl/pdp8_tt.v
index cc320d6..dcadc95 100644
--- a/rtl/pdp8_tt.v
+++ b/rtl/pdp8_tt.v
@@ -124,7 +124,7 @@ module pdp8_tt(clk, brgclk, reset,
    
    // combinatorial
    always @(state or iot or io_select or mb or
-	    rx_int or tx_int or io_data_in or rx_data)
+	    rx_int or tx_int or tx_busy or io_data_in or rx_data)
      begin
 	// sampled during f1
 	io_skip = 1'b0;