David: cyborg or android?!

Here is something I'm curious about. Is David an android or a cyborg?! I ask this because I'm taking into consideration the time period in which Prometheus is placed. Does Prometheus take place 30 years before Ripley was born (2062) or 30 years before Ripley and the others landed the Nostromo on LV-426 (2092)?! Either way whether Prometheus takes place 30 years or 60 years before the Nostromo landed on LV-426, that's a lot of time when it comes to technology. What I'm getting at is this, Ash was highly advanced android significantly so that he was good enough to fool Ripley, Lambert and Parker as pass as human. Which hints at the fact that Ripley and the others are possibly accustom to androids whom you can tell are androids. But as advanced as Ash was, Bishop pointed out that Ash was a sort of Beta model and this was 57 years later. Therefore I don't believe that David is fully an android. As it just doesn't seem feasible that an android that's 120 years older than Bishop would look as close to human as David looks. I speculate that David may instead be a cyborg of some sorts. And that cyborgs might have been the precursors to androids! It may even be that cyborgs are actually individuals whom volunteered for the company as ginny pigs in exchange for extended life?! This might also provide a background for David's seemingly malevolent actions in Prometheus?! Maybe he's dissecting the ampule because he's attempting to evolve himself even further beyond his cybernetic existence?! What are some of the community's theories on David's origin and what role he will play as either an android, a cyborg, a man or a muppet lol (I had to reference the Muppets song to lighten the mood of the post).