How Garbage Collector works?

[Borneq]

Użytkownik "Nick Sabalausky" <a at a.a> napisał w wiadomości 
news:i3vv48$2j19$1 at digitalmars.com...
> langauge  like the JVM are misconceptions. There's nothing about
> pointers that  prevents garbage collection. The pointers do cause some

We have array and pointer that not points at start array. When we have want 
to free memory we mantain 4 bytes pointer+ 4 bytes array positions = 8 bytes 
(=16 bytes on 64 bits !) ?
How can free block when pointer not points to begin of block?