Pass      1: Creates a 79,999 char string & copies it into $a's buffer
Pass      2: Creates a 79,998 char string & copies it into $a's buffer
Pass      3: Creates a 79,997 char string & copies it into $a's buffer
...
Pass 79,999: Creates a      1 char string & copies it into $a's buffer
Pass 80,000: Creates a      0 char string & copies it into $a's buffer