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This is the program for the eighth RetroBattlestations BASIC challenge. In here you'll find a simple BASIC program that plays a game called "Cannonball". The goal is to catch the ball in your cup. The velocity is randomly chosen and you can change the angle of the cannon before firing. After firing try to move the cup to catch the ball. Miss three times and it's game over!

For more details about the challenge, check out the post here:


The code should be fairly straightforward to port. I started with a simple ASCII version on the Apple II and didn't use any kind of dirty tricks. Feel free to add graphics or other features, check Enhancements.txt for more ideas.

See List of Computers With On-Board BASIC

Typing Tips

When typing the program in you can leave off any lines which begin with REM, they are not needed for the program to run. On many platforms you can leave out the whitespace between keywords and operators. IBM BASIC is not one of those however.

Note: On the TRS-80 Color Computer and BBC Micro you need to include the spaces around any IF, AND, OR, or THEN statement.

If you make a mistake and don't want to retype the entire line, most of the BASICs have a way to make corrections.

Amstrad CPC (464/664/6128/464+/6128+)

On Amstrad CPC, use AUTO to start typing commands. Use the arrow keys to move about the line. Exit the AUTO mode py pressing Escape. You can also start on a specific line by entering AUTO 100 (for line 100).

To go to the start or the end of the line use CONTROL+Arrow keys. You can also use SHIFT+Arrow keys to use the copy cursor. This is a second cursor that you move independendly, and will copy whatever is under it to the main cursor when you press COPY.

Apple II computers

On an Apple II+ use LIST to print the line with an error, then use ESC followed by A/B/C/D to move the cursor one step at a time. Position the cursor at the beginning of the line, then use the right arrow to move over the line and fix the error. Be sure to arrow all the way to the end of the entire line before you hit RETURN!

On an enhanced Apple IIe, Apple IIc, or Apple IIgs you can also use ESC with the arrow keys. In 80 column mode (enter with PR#3) the cursor will change to a white block with a + in it, push ESC to drop out of movement mode.

BBC Micro

Use LIST to print the line with a mistake, then use the arrow keys to move up to the beginning of the line. Each press of the copy key will type in the character under the cursor. Make any necessary edits by just typing on the keyboard and using copy to avoid retyping everything.

Commodore 64, Plus/4, and 128

Like the others, use LIST to display the line with problems, then use the arrow keys to move up and make any corrections. By pressing shift-INST you can insert a blank character if you missed something. Unlike the Apple II you don't need to arrow to the end of the line before pushing RETURN.

TRS-80 model 100

This has to be the best built-in BASIC editor I've seen so far! Just type EDIT and the entire BASIC program will be loaded into the built-in word processor where you can make any changes you want. Press F8 to exit the editor and go back to BASIC.

IBM Cassette BASIC, Disk BASIC, Advanced BASIC, GW-BASIC

Type EDIT and it will print the line on the screen and put your cursor at the beginning of the line. Arrow left/right and you can use Insert & Delete to make corrections. Like Commodore BASIC, you don't need to arrow to the end of the line before pushing RETURN.

TI-99/4A Extended BASIC

Type the line number and then arrow up (FCTN+E) and it will enter edit mode with that line loaded. You can move within the line with arrow left (FCTN+S) and arrow right (FCTN+D) and move to the previous or next line with arrow up (FCTN+E) or arrow down (FCTN+X). You can delete the character under the cursor with DEL (FCTN+1) or turn on insert mode to insert extra characters with INS (FCTN+2). You do not need to move to the end of the line before pressing ENTER.

ZX Spectrum Sinclair BASIC

As with other systems, use LIST to display the line with the error, or use Up and Down arrow (CAPS SHIFT+7 and CAPS SHIFT+6 respectively) to select the line, shown by a > characater immediately to the right of the line number, then press CAPS SHIFT and 1 (for EDIT). This will display the line at the bottom of the screen where you can use left and right arrows (CAPS SHIFT+5 and CAPS SHIFT+8 respectively) to move to the error and correct it. Typing will insert characters at the cursor, press DELETE (CAPS SHIFT+0) to delete the character to the left of the cursor. Like Commodore and IBM BASICs, you don't need to move to the end of the line before pressing ENTER.


Cannonball game for BASIC Month 3 on RetroBattlestations



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