Object test

Why is this page displaying the messages below?

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<HTML>
<HEAD>
<TITLE>Object test</TITLE>
<SCRIPT LANGUAGE="JavaScript">

<!-- Begin to hide script contents from old browsers.

function home_computer(brand,memory,year) {
     this.brand=brand;
     this.memory=memory;
     this.year=year;
}

function student(ssno, name, gpa) {
     this.ssno=ssno;
     this.name=name;
     this.gpa=gpa;
}

     student.computer = home_computer;
     marty = new student ("123-45-6789","Marty Hayes", 3.95);
     marty_computer = new home_computer ("Mac", "8Meg", "1994");

// end hiding contents from old browsers -->

</script>
</HEAD>
<body bgcolor="#ffffff">
<script>

<!-- Begin to hide script contents from old browsers.

marty.computer=marty_computer;

document.write("Whose computer?", " ", marty.name, "<p>");
document.write("What brand?", " ", marty_computer.brand, "<p>");
document.write("Lots of memory?", " ", marty.computer.memory, "<BR>");

// end hiding contents from old browsers -->

</script>
</BODY>
</html>