Homework 6 Information, ECS50 Fall 2000

All parts of the assignment are due on Thursday, November 30th
Post any questions on the specifications to the newsgroup
Any changes will also be posted to the newsgroup

Assignment:

SubHunt
The purpose of this assignment is to learn more about the use of interrupts, and to write a large program in assembly language. Both are skills that can come in handy in the future. In order to develop these skills, you are going to design a game similar to the Palm Pilot game "Subhunt". There are specifications which everyone's games must follow, and a list of options of which you must complete (3). You can complete additional options for extra credit.

Game Description:

In this game, there is a ship on the surface of a body of water which can move left and right. There are also submarines that enter either from the left or the right at varying depths. The submarines move directly across the screen at a fixed rate. The ship is able to drop depth charges from either the left or right end of the ship, and these depth charges sink down into the water at a fixed rate as well. If a sinking depth charge strikes a crossing submarine, the submarine is destroyed and the player gets points. The submarines can also occasionally release floating mines, which drift up to the surface. If the ship hits (or is hit by) one of these mines, it is damaged/destroyed.

Here is a very crude asci drawing of what your screen might look like during play. Each "." represents a sinking depth charge, the "*****" are submarines, and each "^" is a rising mine recently released by a submarine. (You do not have to use these characters, I just wanted to give you a feel for how the game looks.)

            
       __+++__
        \___/
----------------------------------
             .       
        .       *****
 ^      
   ^    .                ^
   *****
                      ^
                   ^
            *****

From the top down your screen should contain the following:

Top row : Score and level
Next two rows : Ship
Next row : Surface of water
Next 10 rows : Underwater realm
(Note - you can make a 3-row ship if you want ...)

Here are the specifications that are required:

Your ship must be able to move left and right - use 'h' and 'l' for these movements.
Your ship must be able to drop depth charges off of the left and right sides - use 'k' and 'l' for these actions.
The depth charges must sink at a constant (relatively slow) rate once they have been released.
Submarines must enter from the left and right at "random" times, and move at fixed speeds across the screen (with some moving faster than others).
Submarines occasionally release mines, which float to the surface at a constant (relatively slow) rate.
When any part of a submarine and a sinking depth charge intersect, the submarine is destroyed.
When a rising mine intersects with the ship, the ship is destroyed (and the game ends).

Here are the options which you need to choose three or more:

Submarines are worth different amounts of points, with the ones going faster being worth more (because they are harder to hit).
Have a fixed number of submarines per level, and once all the subs for a given level have either been destroyed or have made it safely across, raise the level (and therefore the difficulty). Also, let the ship take more than one mine hit before it is destroyed.
Make the submarines explode when they are hit and make the ship explode when it dies (visual effects - you know, eye candy!).
Use the extended ASCII character set to make the "graphics" look better. You can find the character set at http://telecom.tbi.net/asc-ibm.html.
The game works like an Atari game - no input is prompted for, the game is turned on and the screen appears. The (r) reset can be pressed at anytime to reset the game to the beginning. The first few levels can be started from by using the (a) to decrease the level and (z) the increase the level. The player should see what level they are on while doing this. The (o) is the off button and it will "turn off" the machine. The (s) will start the game. Pressing (s) during the game will not reset it. This sounds like a lot, but once you do one, the rest should be very similar.
Use the tape drive to keep a high score file. Pressing (h) before the game is started or after it is ended should display the scores. If a game finishes and the score is in the top scores, get the player's initials and add the scores and initials to the high scores. The high score should also be displayed during the game on the top line. If the player breaks the high score during the game, it should show their score as the high score.
Think of your own option and check if it will be okay.