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Written By A. J. Botham


Cover Art
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Loading Screen
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Opening Screen
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Game Screenshot

Circus

A. J. Botham, Lupset, Wakefield

Bounce the flying clown on the end of the seesaw and catapult his colleague into the roof of the Big Top popping balloons as he goes. Achieve extra height by landing him close to the end - but be careful, miss the seesaw altogether and loss life is inevitable. Points are awarded per balloon with a bonus for the completion of a line. Lives are restricted to three but an extra one can be obtained by accumulating more than 5,000 points.

The seesaw can be controlled by either joystick or keyboard the keys being Delete to move left, Copy to move right and Ctrl to turn the seesaw around.

Circus should be entered as follows. First type in program 1 and Save it as "CIRCUS". This sets up the user-defined characters and displays a title page while loading. Next type in program 2 and Save immediately after program 1 as "Circus". In future, when the first program is CHAINed, program 2 will be CHAINed automatically.

For disc users, program 2 is too long to run due to the lack of memory in Mode 2. This problem can be overcome by adding an extra line to program 1 as follows:

55 PAGE = &1200

The programs can then be saved as before.

Although Circus is written entirely in Basic the game runs extremely quickly. This is due to the use of structed programming techniques as well as extensive use of the GCOL 3,X command and string handling functions for smooth flicker-free graphics. Full use is made of the BBC's SOUND and ENVELOPE commands to provide some realistic sound effects which merge nicely with the animated graphics. A hall of fame is included which makes excellent use of Mode 7 as does the title page. Here is a brief explanation of the program.

Each line of balloons is held as a string. This makes life easy by allowing the use of the LEFT$ and RIGHT$ functions for scrolling the balloons. When a balloon is burst, the MID$ function is used to place a space in the required position. A count of the number of balloons burst in each line is kept so that a new line of balloons can be produced upon completion of the line.

As the clown flies through the air, his path is governed by the equation Y=mX2 where m is a constant. The height reached by the man can therefore be varied by changing the value of m.

The GCOL 3,X command is used for speed and for its ease of use. When the character is printed, the foreground colour to be used, X, is Exclusively-ORed with the colour already there. One of the advantages of this method is that the character can then be deleted by printing again with the same foreground in the same place. This method is also used when moving the seesaw.