I'm using PHP 4.3.1 with Apache 2.0.44 with the following directives set in my httpd.conf:

ServerRoot /var/www
# ...
Listen 8080
# ...
LoadModule php4_module lib/libphp4.so
# ...
AddType application/x-httpd-php .php .phtml .php4 .php3
AddType application/x-httpd-php-source .phps
# ...
Options Indexes
# ...
DirectoryIndex index.html index.php

I have one file in my server root: index.php:

- - - - - - - - %< CUT HERE >% - - - - - - - -

    <!-- File: index.php -->
    <pre>
    <?php
    var_dump($_SERVER['SCRIPT_URI']);
    ?>
    </pre>

- - - - - - - - %< CUT HERE >% - - - - - - - -

If I go to http://localhost:8080/index.php, I get the following output:

    <!-- File: index.php -->
    <pre>
    string(31) "http://localhost:8080/index.php"
    </pre>

However, if I go to http://localhost:8080/, I get the following output:

    <!-- File: index.php -->
    <pre>
    string(17) "http://localhost/"
    </pre>

This also happens with Apache 1.3.27 and an equivalent configuration.