PCW8307.TXT
Issue #27, 7.Jul.83, page 37

CROSS THE RIVER (aka. River Cross)

This is the computer version of the children's game, the object of which is
for a man to cross a fox, a hen and a bag of corn from one side of a river to
the other in the minimum number of crossings, but only taking one passenger
at a time.

        The man must not leave behind certain incompatible combinations; ie.
hen with the fox and/or corn, in which case you have failed and the game is
over. To move man and fox or hen or corn enter the appropriate number. To
cross the man only enter '1'. The program also takes into account invalid
moves. Uses 2K.





Issue #28, 14.Jul.83, page 33

BOUNCING BALL

Here is a program to show what can be done with the 1K of ZX81 memory in BASIC.

        It displays the path of a bouncing ball moving from left to right
across the screen. By adding UNPLOT statements to lines 115 and 225 the ball,
by itself, bounces along in real time.

	By adding the following line:
145 IF D=VAL "64" THEN RUN
the ball restarts after reaching the right-hand side.

        All three lines will fit into memory, but the ball may "miss" or
might not appear at the place you expected.

Variables
H - Height of ball
G - Gravity (acceleration of 1kg per second) [sic]
D - Distance travelled (horizontally)
A - Speed of ball

Program notes
Lines
110-160	Routine for ball going down
220-270	Routine for ball going p
100	Balances line 210
210	Increases G so ball slows up quicker (to simulate the energy lost through
	sound & heat). [sic!]



Popular Computing Weekly 21/07/1983 Page 29

Race for the ZX Spectrum

The object of this game, written for the ZX Spectrum, is to steer your 'car'
around the race track, avoiding the sides and trying to reach the finishing
post, shown as a capital 'F'. This is quite hard to do - I have only managed it
a couple of times. If you think it is too hard, you can easily change the track
by altering lines 60-120. The graphics characters in line 15 are in
'alphabetical order', the second a graphic 'B', etc. Make sure that the
graphics string G$ in line 9010 is typed in the order shown.

You can change the For NEXT loop in line 155 to alter the speed of the car. Or
you can remove the line completely to make the car go at full speed. I added
line 155 to the original program to make the game more easier to play, as the
car was much too fast to make a playable game.

Program notes

3-50		Initialisation
60-120		Draw track
140-250 	Main Loop
300-320 	Crash routine
9000-9270	Graphics setup

Use key 'M" to steer to the right, and key 'N' to steer to the left.
