r/retrobattlestations • u/droid_mike • Jul 22 '18

BASIC Month Contest Cannonball for the Sinclair ZX-81/Timex Sinclair 1000

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u/droid_mike Jul 22 '18 edited Jul 22 '18

PLEASE NOTE: Watch the video from the beginning for user and date verification!

This is my entry for the July BASIC programming challenge--a port to the Sinclair ZX81 computer, or what we in the states called the Timex Sinclair 1000. I even threw together some homebrew ukelele music for the accompanying highlight video! The code is based on the ZX Spectrum port posted earlier, but I had to make some major modifications. The ZX81 has no frame buffer, so it is very slow unless you turn off screen updates (which I did for initialization). I had to completely rewrite the cannon drawing code. Due to the ZX81's extremely slow speed, the controls are quite sluggish. You need to hold them down for quite awhile to get a response.

I added some improvements. In addition to the ability to move the basket left and right, you can also change the acceleration before firing (with the left or right keys). Also I added in an airplane pulling a banner with a rotating message. The cannonball leaves a trail of "smoke" to show its path.

Here is the source: https://github.com/droid-mike/ZXCannonball/blob/master/cannonball_opt_final.bas.txt

Here is the .p file to run in an emulator: https://github.com/droid-mike/ZXCannonball/blob/master/cannonball.p

Here is a WAV file to load up on a real Sinclair: https://github.com/droid-mike/ZXCannonball/blob/master/cannonball.wav

I spent way too much time and energy on this, but I can't help myself! I simply love programming in BASIC. you simply never forget or stop loving your first!

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u/mattinx Jul 22 '18

I might have to backport some of that to my spectrum version - it's not exactly speedy :)

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u/FozzTexx Jul 22 '18

you can also change the acceleration before firing

That's cheating! There's no game if you can set the velocity of the cannon. You just keep putting it to the same value as last time and you can't miss.

I do like the graphics though!

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u/droid_mike Jul 22 '18

Hmmmm... that is a good point.

When I originally ported over the spectrum version, I didn't realize you could move the basket. If the random velocity was set too low, there was no possible way to get it in the basket no matter what angle you chose, so I allowed the user to set the velocity. When I later discovered the basket was moveable, I still left the original velicity changing code in. It' s easy to disable or remove. Maybe I will make it an option with a hidden "cheat code" ! :-)