Instead, sights were set on using the only other way in to the console – through the DVD drive. The only burnable media the PS2 DVD drive will normally read comes in the form of DVD video discs.
He explains that the PlayStation 2 couldn’t keep the entire open-world game map in its tiny 32 MB of RAM. Instead, models had to be streamed from the DVD drive as the player moved around the world.
The PS2 was a forward-thinking ... one of the cheapest ways to get a DVD player back then. It later supported internet connections and an adaptable hard drive to store memory.