STARTER PACK
Sinclair User, September 1984


MATHS TEST

Sharpen your mental arithmetic with Maths Test for the 1K ZX-81
by David Steel of Beith, Ayrshire. The program will ask you to
do a number of sums, telling you the correct answer if you are
wrong.

The graphics at lines 50 and 60 print a large question mark on
the screen. Notice also that at line 100 the random numbers
chosen by the computer for the sums must be printed as whole
numbers by using the INT function. If you want to change the
sums to subtraction or other operations, change the plus sign
in lines 100 and 105 to the appropriate symbol.


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MISSILE STRIKE

Mark Young of Hull wrote Missile Strike, a simple arcade game for
any Spectrum. You must use cursor keys 1 and 2 to move your
spaceship and 0 to fire your laser in an attempt to shoot down
the missiles threatening the existence of Earth.

Lines    1-   9  Read the data for the user-defined graphics.
                 The data is held in line 1040 in binary form,
                 using the BIN command. The information is POKEd
                 into the eight bytes where the layout of the
                 graphics character T is stored. For a full
                 explanation of the process, read chapter 14 of
                 the Spectrum manual.
Lines   10-  24  Mainly decorative but also set a few variables to
                 zero for later  use.
Lines   25-  80  Print instructions for the game if requested.
Lines   90- 280  Print the basic screen for the game.
Lines  290- 310  Set the initial co-ordinates for your spaceship,
                 which will be represented by the letter D. The
                 co-ordinates are set both for character squares and
                 for the single pixels, so that your laser fire can be
                 drawn at the proper place.
Lines  394- 396  Set up the position for the enemy at random.
Lines  400- 402  Print your spaceship and get ready to print the laser fire.
Lines  405- 425  Adjust the co-ordinates according to which key you press.
Lines  439- 445  Variable u holds the length of your laser fire. The other
                 lines draw it depending on the position of your ship.
Line   460       If p is less than three you have failed to stop the missile.
Line   470       Removes the previously printed missile in preparation to
                 printing it again elsewhere.
Line   480       You missed the missile but have another chance to hit it.
Line   490       A new missile is required.
Line  1040       The DATA statement for the user-defined graphics.
Lines 4095-4098  You have destroyed a missile, so the program prints a
                 crude explosion and makes a noise.
Lines 5000-5020  Line 5000 makes more noise. Line 5010 and 5015 add to your
                 score and count the number of missiles in w. If you have
                 destroyed 10 missiles you win, otherwise the program returns
                 to 391 for a new missile.
Line  5100       Having destroyed 10 missiles you are congratulated and the
                 program plays a tune. Following that, the program will RUN
                 again.
Lines 6000-6030  A missile has got through to Earth. Variable v holds the
                 number of failures and if there are more than 10 you lose.
Line  6100       You have lost the game and a message is printed. The program
                 will then RUN again.


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SANDWICH

You are a little fly which has been guzzling the jam from a
sandwich when suddenly the two halves of the bread start to
close. You must use cursor keys 5 and 8 to reach a hole in the
bread before you are crushed to death.

The game runs on the ZX-81 in 1K and was written by Erik Smit
of Leidschendam in the Netherlands.
