Atlantis is a game created fo the ATARI 2600 and ported to the Spectrum using the AGD
suite by Luca Bordoni.
Despite being a game developped using the AGD engine, it has a lot of added functions
using assembly language and besides it uses a patch by Allan Turvey that allows
the developper to use wide sprites measuring 32x16 pixels instead of standard 16x16
or 16x24 sprites.
Fortunately, Luca was very kind and sent to me all of the working docs he has about
the conversion of this game.
AGD allows the programmer to add a file containing aseembly code as a .USR file that
gets compiled together with the engine and AGD commands file
The .USR file I have created for this game has about 1700 code lines and once compiled 
it uses almost 4Kb of code and data!
In this file Luca included seven sound effects that need to be converted with care
counting the T-States for the ZX-Spectrum code and using the 6809 opcodes that 'use' 
the numer of cycles that match that time ...
The menu screen was saved after compressing it, so the subroutine that uncompresses
it, reading a table inside the code, receives the screen bytes in the order that ZX 
expects them, very different than the order needed on the MC6847, so you will see that 
the screen is drawn imitating the ZX load system.
By default the playing keys are: 'O' for left canyon, 'P' for right one and 'Q' for
the central canyon. But you can redefine them using option '3' in the main menu.
You begin with seven lives, and losing one implies the lost of an element you were
protecting ... 
Each 10,000 points you score, you are rewarded a life and one of the destroyed objects 
is created again (if any). This is true till 90,000 points, but not with greater scores.
I just added an option to quit a game if you wanted to, just pressing '4'

I hope you'll enjoy that one
Pere Serrat
