sailars,
<!DOCTYPE HTML>
<html>
<head>
<title>Untitled</title>
<meta charset="utf-8">
<script>
window.addEventListener('DOMContentLoaded', function() {
var form = document.querySelector('[name="Tecт"]');
form.addEventListener('click', function(event) {
var type = event.target.type;
type == "button" && (form.Im_stud.value = event.target.value)
});
});
</script>
</head>
<body>
<html>
<head>
<title>Тест по составу компьютера</title>
</head>
<body>
<form name="Tecт">
<p><input type="text" name="Im_stud" size="15">
<p><input type="button" value=" вверх "></p>
<p><input type="button" value=" вниз "></p>
<p><input type="button" value=" влево "></p>
<p><input type="button" value=" вправо "></p>
<input type="reset" value="Очистить"></p>
</form>
</body>
</html>
</body>
</html>