Submarino Experimental Neptuno

This is one of those games on which it's extremely difficult to say something without the manual, and I fear it will be so difficult to get it.

We know it is a submarine simulator, which consists of two visible phases. The first tells us that the enemy is gathering off the coast of Gibraltar, and that we must destroy it.
Then appears a screen with a countdown, sooo slow, that decreases at the same time that another counter, of points in this case.
Also the game gives us a password, but I have no idea what it does. Moreover we are told that by pressing "m" we will access the map (however, although I did it lots of times, nothing happened).

Once this stage have been finished (I have activated the turbo on the emulator because it is unbearable), we reach the submarine's control room, where I have no idea about what to do.

To be honest, the game is so crappy that I don't think that the manual will help a lot, but who knows.