Blockbreaker New Routines

By Dave Hitchens


Issue 22

Jul/Aug 86

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In response to a request from the editor I present a joystick version of the game Blockbreaker which was published in issue 20. As a bonus, or maybe to frustrate those of you who can't get past level 2(!), I have also included an auto-play modification so you can see just how the game should be played.


Before we begin, however, a correction to the original program. Blockbreaker was written on a 32k Atari 400 and until very recently I was unable to test it on the XL or XE. Unless you also use a 32k machine you will find that the high score feature is not displayed between games. Fortunately the correction is a very simple one. Referring to the original listing in Issue 20, line 155 should be modified by changing the '120' in the fourth statement to 'PMB' as follows.


I did not include a joystick routine with the original version because I felt that the use of a joystick made the game virtually unplayable since it lacks the precision of the analogue input which a paddle provides. I suppose, to some degree, it will depend on the individual's dexterity and reaction time so I've listed the modified lines below for you to try for yourself.

Type in the original program from Issue 20, or load it if you have already typed it in, and then modify it as follows.

Change the following lines

Now add

The 29th DATA statement in line 1940 controls the sensitivity of the joystick. Change its value (4) to alter the speed of your bat. Since it controls the delay loop, increasing its value will slow down the bat.

The code in line 1940 causes the bat to move at a constant speed. I have not experimented with an accelerating bat since I felt that this would cause further frustrations during play but if anyone wishes to dabble with the routine, ensure that your machine code fits into the listing between lines 1930 and 1950 and that it ends with an RTS (I've used location 7 as the delay variable).


If you would like to see the game demonstrated then make the following changes and additions to the original (i.e. paddle) version of the game. Now sit back and watch Atari do all the work. Of course you could always plug in a paddle and pretend you are a real champion!

Change the following lines

Now add

Blockbreaker will play forever in this mode (and introduce a minor bug at the higher levels!) so you may like to make the Atari a bit more 'human' by modifying the above version as follows.

Change these lines

The Auto routine is again situated between BASIC lines 1930 and 1950 and machine code freaks will be able to decipher the routine given the following information.

Location 1537 - the ball's (Player 2) vertical position in the PMG table.
Location 1539 - the ball's horizontal position.
Location 1541 - the bat's (Player 0) horizontal position (left edge).
Location 7 - the 'random' variable.

The bat is either 12 or 8 colour clocks wide in the Auto mode.

So there you have it. Blockbreaker playable with paddles, joystick or even a Touch Tablet! If you get hooked on it you may find that you want to go and get some paddles after all, especially if you want to get as good as that Auto mode!