It works fine for me using
Java 8 on OS X. Offhand, I can't think of a reason why it wouldn't work elsewhere, since appletviewer would presumably work the same on all platforms.
As an aside, you should get in the habit of using double quotes around both names and values:
<param name="fontName" value="Courier"> rather than
<param name = fontName value = Courier>.
And, of course, applets are completely obsolete by now, so you should switch to learning standalone applications (or Java Web Start applications) instead, using JavaFX or Swing rather than AWT.