This issue
we have a listing showing how easy it is to move Player/Missiles
using the Turbo Basic commands MOVE and -MOVE. Just type in the
listing using TURBO BASIC and RUN it. When you hear a beep, type in
any message up to 26 characters long.
The program uses fairly standard Player Missile Graphics which have
been explained in several other articles so I will only run through
the commands used which are unique to TURBO BASIC.
Line 140: This line places zeroes in the player missile area,
I used 20000 by trial and error to find an area of 2K which was not
being used and therefore full of zeroes.
Lines 205-230: This moves the character data from the
character set in ROM to the player 0 area. The data at the end of
the program is in ATASCII character codes, you have to subtract 32
from this because the first character stored in the set is SPACE (ATASCII
32).
Line 245: Moves player 0 down.
Line 255: This takes the bottom byte and moves it to the top,
which allows the player to scroll around the screen.
Lines 340-380: This uses REPEAT-UNTIL loops to move player 1
from left to right.
Lines 440-480: I have used WHILE-WEND loops to show the
difference to REPEAT-UNTIL. In this case either can be used, but
normally one of these would suit the job better.
Lines 520-555: Gets the characters typed in and places them
in player 3. I have used an IF-EL SE-ENDIF to show how this can be
used.
PROC MOVE: This is an endless loop with all the movements for
all four players together. These are the only lines you need to
actually move the players depending on which direction you want to
go.
I hope this listing will give you the courage to use Player/Missiles
in your Turbo BASIC programs, without having to worry about machine
code.
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CAN YOU WRITE TURBO PROGRAMS?
Don't forget we will pay £20 for an example of
Turbo programming. The listing must be short enough to fit on one
page and must use the features that are unique to Turbo Basic. You
will have more success in getting your listing accepted if you
choose an area of programming which has not already been covered.
Send your contributions on disk to the Editorial address on page 3.
WHAT IS TURBO BASIC?
Turbo Basic is a powerful BASIC language for the
Atari originally published in the German magazine Happy Computing
who retain the copyright but have released the program to the public
domain. It adds over 60 new commands to Atari Basic, runs three to
five times as fast, yet is totally compatible with existing Atari
Basic programs. It comes with a compiler that will compile any Atari
Basic or Turbo Basic program to run at machine language speed.
You should be able to get a copy from any source
of Public Domain software such as your local user group or the PAGE
6 Accessory Shop.
