
SINCLAIR PROGRAMS
May/June 1982
ZX81_Games Contents

BOMB
COMPUTER COMBAT
DOGFIGHT
FORCE FIELD
GRAVITY
LUNAR LANDER
NIGHTFALL
QUEST
ROAD RACE
ROCKET ATTACK
SINK THE BISMARCK
SMAUG
SPACE SHOOTDOWN
SPACEYS
STAR GATES
SUB CHASE
WANDER
ZAP


- - - - -
BOMB

THE IDEA of Bomb is to blow up undefined enemies,
represented by an inverse space. Your bomb moves across the
top of the screen and pressing any key will release it. Only
one bomb can be in the air at any time, limiting the
attraction of the game, but it will run on 1K machines.

For those with slow mode the PAUSE and POKE may be removed
by deleting lines 100 and 110. Bomb was submitted by David
Goodup.


- - - - -
COMPUTER COMBAT

THE FIRST question often asked about a new machine is "Does
it play Space Invaders?". Though a 1K machine has
considerable difficulty getting anywhere near, Computer
Combat for 1K ZX-81 is a type of mini space invaders but
with only one invader and one base and a much slower rate of
firing.

The object of the game is to hit the invader as many times
as possible before it lands or you run out of missiles.
Twenty-five missiles normally are given but that can be
altered by changing the value of B in line 5.

You receive five points for hitting it but lose one is you
miss. Use keys 5 and 8 to move left and right respectively
and key 0 to fire. The invaders' missiles are shown as an
asterisk and yours as a cross. The program is good for
beginners, as it is easy to understand the function of each
line as there are none of the usual POKES and PEEKS or other
complicated functions.

If you want to get more memory, enter in direct mode the
following BEFORE entering the program: POKE 16389,88
followed by NEWLINE NEW followed by NEWLINE

The program will run continuously until the BREAK key is
used. Computer Combat was sent in by 15-year-old Anthony
Wells, of Totnes, Devon.


- - - - -
DOGFIGHT

THE GRAPHICS on Dogfight are fairly impressive considering
that it will run on 1K machines. The screen becomes the
windshield of an aircraft with your gunsights indicated by
the symbols. An enemy aircraft flies on a random course
across the screen, moved inexorably rightwards and
downwards.

Using certain cursor keys, e.g., upward arrow, the course of
the aircraft can be altered in an attempt to put it in front
of the sights. When that is done, pressing the 0 key will
fire your gun.

Program author Robert Graves of London explained that he
limited the amount of cursor control deliberately; you
cannot move the aircraft downwards. The result is a game
which it is not so easy as it sounds.


- - - - -
FORCE FIELD

AS COMMANDER of a Force Field which guards a city you have
to defend it against a squadron of hostile UFOs. The force
field has to be controlled to destroy enemy bombs before
they hit the city. If the field is activated too soon the
power is dissipated and will not destroy the bomb.

The radar screen identifies each UFO with a number from 1 to
9 and you have to hit the correct number key to identify the
UFO which dropped the bomb when it enters the force field.
There are four levels of difficulty.

The program has been supplied by Video Software of
Stourbridge, whose ambitious products include a financial
modelling package, graphics, a private version of
teletext/viewdata (sic), and games ranging from sports to
the Stock Exchange. All are available on the ZX-81 and most
on the ZX-80 with 8K RAM.


- - - - -
GRAVITY

GRAVITY for 1K ZX-81s envisages aliens spreading rubbish
across the universe. Your task is to take control of an
Earthling dustbin and clean the solar system after a
particularly raucous all-night party.

Gravity fills the screen with debris initially and then
gives you your waste disposal unit which begins to move down
the screen quickly due to the gravity in space - surely some
mistake there? Using keys 6, 7 and 8, the dustbin can be
moved left, right and up respectively but should you run off
the screen, the game finishes.

The program was sent in by Paul Ralphs of Manchester who,
apart from re-designing the laws of astro-physics, made the
game exceptionally difficult by giving the player an
invisible dustbin. To help beginners we have inserted an
asterisk but when you feel sufficiently confident delete the
asterisk from line 130 but leave the two spaces.


- - - - -
LUNAR LANDER

LUNAR LANDER is yet another 1K program from Looker and son.
This is a superior version of the lunar landing game. Your
spacecraft is 600ft. above the lunar landing pad and
descends automatically at a velocity of 20 feet per second.

The initial fuel reserve is 130 gallons and to achieve a
safe landing you must fire your retro-rocket thrusters - by
pressing the T key - to slow the machine and, allowing for
the random drift of the spacecraft, attempt to land on the
landing pad displayed.

Lunar Lander displays remaining fuel, altitude and velocity
in the top right-hand corner of the screen, while the
spacecraft descends on the left-hand side. Too much thrust
and the spacecraft begins to ascend, shown by a negative
velocity reading, while too great a speed in landing causes
a crash.


- - - - -
NIGHTFALL

NIGHTFALL requires 4K RAM and involves blowing-up
skyscrapers from a glider flying over a city. You start by
entering a number between zero and 10 to define how high you
want the skyscrapers built. The glider is represented by an
inverse plus sign and flies from left to right, getting
lower each time it goes across the screen.

Because of the gradual loss of height it is imperative to
eliminate the more protruding buildings before you crash
into them.

Pressing 0 will release a bomb and only one bomb may be in
the air at a time. Points are scored for each portion of
building destroyed. to start the game again after reducing
the city to ruins and landing or crashing, enter a new level
of difficulty to the display file.

Nightfall was sent in by Tim Rogers of Richmond, Surrey.


- - - - -
QUEST

QUEST is an adventure program based on a journey through a
cave system, the objective being to amass a personal sum of
#100. Money is gained by killing monsters and you start with
a strength rating of 20. On being attacked by a resident
monster, any instruction which takes the fancy may be
entered, so long as it does not begin with the letters R or G.

Thus, instructions such as shoot, hit, stab, bash or, for
the gentler among you, perhaps even tickle, may be entered
and a random score is assigned to tell you how you fared.

Weaker monsters can be killed by one action but each attempt
reduces your strength rating and when it equals zero you are
unfortunately extinct.

Having killed. a monster you may rest (key R), which gives
you two strength points, or continue (key G) but resting
involves the danger that another monster sneaks up on you.
Finding a magic ring makes you invisible and you can run
away in the middle of a battle. A magic staff (key G)
doubles fighting power for the rest of the game, while a
magic potion doubles strength only for that attempt.

If strength diminishes during a battle, a sum of money can
be traded for strength by typing Change as a course of
action - #1 equals three strength points. To clear the
program, press Stop.

The program is from a tape of programs produced by Richard
Shepherd Software of Maidenhead, Berkshire. Called Bargain
Bytes 1, it comprises eight programs - five games and three
covering bank accounts, working out loans and foreign
exchange conversion. It costs #5.



- - - - -
ROAD RACE

ROAD RACE is the most outstanding program using moving
graphics and fitting on a 1K machine we have seen so far.
The object of the game is to steer your car, represented by
an inverse H, on a twisting road while avoiding other cars
which appear at random.

The car moves forward automatically but can be steered left
and right by using the cursor controls - keys 5 and 8. If
you crash into another car or run off the road, the game
stops and your score is displayed - top score in the
Sinclair Programs office was 66.

To keep going requires some skill and for once it really is
a game which can provide hours of amusement.

Road Race was one of three games submitted by David Looker
and son from Swindon, Wiltshire.


- - - - -
ROCKET ATTACK

IN Rocket Attack for 1K machines the player is in control of
a guided missile launcher defending the shores from air
attack. A rocket launcher is situated at the bottom
left-hand corner of the screen, while enemy planes approach
at random height from the right.

To fire, the P key is used and, when depressed, a rocket is
launched, rising at 45 degrees. The rocket will continue its
advance only as the key is depressed, so there is a measure
of control over its progress. Aircraft can be destroyed
either by scoring a direct hit or by leaving the rocket in
the path of the aircraft.

Rocket Attack was submitted by D E Healey of Coseley, West Midlands.


- - - - -
SINK THE BISMARCK

IN TRUE jingoistic fashion, Sink the Bismarck puts the
player on a routine patrol of the North Sea. Out of the fog
appears the Bismarck and by setting elevation and muzzle
velocity of a gun, you can attempt to sink the ship.

The program is taken from Peek, Poke, Byte and RAM - Basic
Programming for the ZX-81. It is published by Shiva
Publishing of Cheshire. Forthcoming titles include Machine
Code and Data Structuring for the ZX-81 and The ZX-81 Add-on
Book, both at #7.50.


- - - - -
SMAUG

SMAUG is an Adventure game based on a circular maze of rooms.

The object is obviously to find a dragon called Smaug and
then kill it. On the way you risk being transported to other
caves by Orcs or catching sight of a dreaded Balrog, which
is fatal instantly.

Having slain the dragon, you must steal the Arkenstone which
assists you by protecting you from Orc-porting and also
warns of impending Balrogs.

Smaug has no graphics built in yet but perhaps that could be
the next development for interested readers.

The program requires 5K and was submitted by Mrs C M Corns
of Enfield.


- - - - -
SPACE SHOOTDOWN

SPACE SHOOTDOWN, by G L J Tily, provides a test of your
skill in estimating distance and angles. Play the game a few
times and you will be amazed at how clever you become at
estimating correctly.

Your base is at the bottom left of the screen. The invader
is the black piece. Your task is to shoot it down in as few
shots as possible. First enter the angle of the ship from
your base, or as good a guess as you can estimate, then
enter the distance from your base. Remember that the screen
is 63 units across. You will get a satisfying BOOM when you
get the two figures correct.


- - - - -
SPACEYS

ANOTHER game for 1K ZX-81 is Spaceys, in which a space ship
cruises overhead. Using the 1 key will fire a missile,
represented by an asterisk, which can then be guided using
the 8 key for left movement and the 0 key for right movement.

When 200 ships have passed overhead your score and the best
score so far are displayed. Hitting the middle of the ship
scores 25 points, while clipping the ends rates 10. The
missile can be guided both on the ground and in the air.

Spaceys is from The Gateway Guide to the ZX-81 and ZX-80 by
Mark Charlton. Published by Interface of 44-46 Earls Court
Road, London WB 6EJ.

[You have the game 'Spaceys' from Sinclair Programs May/June 1982 as corrupt.]
[As noted in the text for the game, it was originally published in the book  ]
['Guideway Guide to the ZX81 and ZX80' and so I have been able to make       ]
[corrections to the programs by referring to the book. I still found there   ]
[was a bug in line 140 where 'GOTO 180+...' should have been 'GOTO 150+...'. ]
[                                                                       PaulF]


- - - - -
STAR GATES

STAR GATES is a 1K program in which the sun is about to go
super nova and a fleet of space ships is waiting to depart
from Earth to escape the holocaust. The object is to guide
each ship through star gates.

The space ship is situated at the bottom of the screen and
key 1 is used to move vertically upwards and keys Q and P to
move left and right respectively.

Star Gates was submitted by D E Healey of Coseley, West Midlands.



- - - - -
SUB CHASE

SUB CHASE is another 1K program submitted by the Lookers
father and son team. In this, you are given a static
destroyer in the top left-hand corner of the screen, while
an enemy submarine travels from left to right across the
screen.

Using the F key drops a depth charge and it must be dropped
at precisely the right moment so that it scores a direct hit
on the conning tower of the submarine.

Sub Chase gives you 10 submarines before the game ends and
your score is displayed on the screen.


- - - - -
WANDER

AN ADVENTURE game, Wander uses limited graphics which will
run on 1K machines. It is set in a circular maze with the
usual interconnecting square rooms. Only one room - the one
you are in - is displayed and alternate rooms contain gold,
with your position in the maze being estimated from the
amount of gold in nearby rooms.

The object of the game is to amass as much gold as possible
and find an exit to the maze but with only 60 units of food
- allowing up to 60 moves - you could well starve before
finding an exit.

If you are desperate, walls can be clawed through but so
exhausting is that operation that it uses 10 food units. One
room is dialled at a time, showing the possible direction of
exit and inputting, L, R, F, B indicates whether movement is
required in a left, right, forward or backward direction.

The letters G, W and F indicate the amount of gold in the
room, the total wealth accumulated so far, and the amount of
food remaining.

To repeat the same maze in a subsequent game, set R to a
particular value between 0 and 1.

Wander was submitted by Michael Orwin of London who intends
to include it in a forthcoming book called 1K Wonders. He
also sells games cassettes for the ZX-81 and can be
contacted at 26 Brownlow Road, Willesden, London NW10 9QL.


- - - - -
ZAP

ZAP is described as a kind of mini-invaders and will run on
1K ZX-81. Intruders from outer space approach diagonally,
left, right and vertically. A missile is launched
automatically at the invaders and you have to steer the bomb
to its target, using the 5 and 8 keys - left cursor and
right cursor.

Ten invaders are launched and then the program tells you how
many you stopped. When familiar with the game try changing
line 130 to IF C+H AND M=P THEN GOTO 200.

Zap is from The Gateway Guide to the ZX-81 and ZX-80 by Mark
Charlton. Published by Interface of 44-46 Earls Court Road,
London WB 6EJ.

