diff --git a/misc/yosys.html b/misc/yosys.html
index c82bc187..929d0dd3 100644
--- a/misc/yosys.html
+++ b/misc/yosys.html
@@ -1,60 +1,72 @@
-<html>
-  <head>
-    <title>yosys.js example application</title>
-  </head>
-  <body onload="document.getElementById('command').focus()">
-    <h1>yosys.js example application</h1>
-    <div><textarea id="output" style="width: 100%" rows="30" cols="100">Loading...</textarea></div>
-    <div><form onsubmit="return run_command()"><tt><span id="prompt"><br/>yosys&gt; </span></tt><input id="command" type="text" size="100"></form></div>
-    <script type='text/javascript'>
-      var got_log_messages = false;
-      var Module = {
-        print: (function() {
-          var element = document.getElementById('output');
-          if (element) element.value = ''; // clear browser cache
-          return function(text) {
-	    got_log_messages = true;
-            if (element && typeof(text) != "number") {
-              element.value += text + "\n";
-              element.scrollTop = element.scrollHeight; // focus on bottom
-            }
-          };
-	})(),
-        printErr: (function() {
-          var element = document.getElementById('output');
-          if (element) element.value = ''; // clear browser cache
-          return function(text) {
-            if (element && typeof(text) != "number") {
-	      console.log(text);
-	      if (got_log_messages) {
-                element.value += text + "\n";
-                element.scrollTop = element.scrollHeight; // focus on bottom
-	      }
-            }
-          };
-	})(),
-	command: (function(cmd) {
-	  Module.ccall('run', '', ['string'], [cmd])
-	}),
-	prompt: (function(cmd) {
-	  return Module.ccall('prompt', 'string', [], [])
-	})
-      };
-      function run_command() {
-        var cmd = document.getElementById('command').value;
-	document.getElementById('command').value = '';
-        Module.print(Module.prompt() + cmd);
-	try {
-		Module.command(cmd);
-	} catch (e) {
-		Module.print('Caught JavaScript exception. (see JavaScript console for details.)');
-		console.log(e);
-	}
-	document.getElementById('command').focus();
-	document.getElementById('prompt').innerText = Module.prompt();
-	return false;
-      }
-    </script>
-    <script async type="text/javascript" src="yosys.js"></script>
-  </body>
-</html>
+<html><head>
+	<title>yosys.js example application</title>
+</head><body onload="document.getElementById('command').focus()">
+	<h1>yosys.js example application</h1>
+	<div><textarea id="output" style="width: 100%" rows="30" cols="100"></textarea></div>
+	<div id="wait" style="display: block"><br/><b><span id="waitmsg">Loading...</span></b></div>
+	<div id="input" style="display: none"><form onsubmit="return run_command()"><tt><span id="prompt"><br/>yosys&gt; </span></tt><input id="command" type="text" size="100"></form></div>
+	<script type='text/javascript'>
+		var got_log_messages = false;
+		var Module = {
+			print: (function() {
+				var element = document.getElementById('output');
+				if (element) element.value = ''; // clear browser cache
+				return function(text) {
+					if (!got_log_messages) {
+						document.getElementById('wait').style.display = 'none';
+						document.getElementById('input').style.display = 'block';
+						document.getElementById('waitmsg').innerText = 'Waiting for yosys.js...';
+						got_log_messages = true;
+					}
+					if (element && typeof(text) != "number") {
+						element.value += text + "\n";
+						element.scrollTop = element.scrollHeight; // focus on bottom
+					}
+				};
+			})(),
+			printErr: (function() {
+				var element = document.getElementById('output');
+				if (element) element.value = ''; // clear browser cache
+				return function(text) {
+					if (element && typeof(text) != "number") {
+						console.log(text);
+						if (got_log_messages) {
+							element.value += text + "\n";
+							element.scrollTop = element.scrollHeight; // focus on bottom
+						}
+					}
+				};
+			})(),
+			command: (function(cmd) {
+				Module.ccall('run', '', ['string'], [cmd])
+			}),
+			prompt: (function(cmd) {
+				return Module.ccall('prompt', 'string', [], [])
+			})
+		};
+		function run_command() {
+			var cmd = document.getElementById('command').value;
+			document.getElementById('command').value = '';
+			Module.print(Module.prompt() + cmd);
+			document.getElementById('wait').style.display = 'block';
+			document.getElementById('input').style.display = 'none';
+
+			function run_command_bh() {
+				try {
+					Module.command(cmd);
+				} catch (e) {
+					Module.print('Caught JavaScript exception. (see JavaScript console for details.)');
+					console.log(e);
+				}
+				document.getElementById('wait').style.display = 'none';
+				document.getElementById('input').style.display = 'block';
+				document.getElementById('prompt').innerText = Module.prompt();
+				document.getElementById('command').focus();
+			}
+
+			window.setTimeout(run_command_bh, 50);
+			return false;
+		}
+	</script>
+	<script async type="text/javascript" src="yosys.js"></script>
+</body></html>
