Disabling buffering on STDOUT seems to do the trick. Using strict and lexicals does hurt either.

#! perl -sw
use strict;
use Win32::Console ;

$|++; # Disable buffering on STDOUT.

my $password;

my $cons = new Win32::Console(STD_INPUT_HANDLE) || die "Can't open new
+ console\n";
my $oldMode = $cons->Mode ;
$cons->Mode(~(ENABLE_LINE_INPUT|ENABLE_ECHO_INPUT) & $oldMode );
while (1) {
    my $char = $cons->InputChar(1) ;
    last if ord $char == 13 ;
    print '*' ;
    $password .= $char ;
}
print "\nPassword was $password\n" ;
$cons->Mode($oldMode) ;
__END__
P:\test>junk
****
Password was fred
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