Here are some ideas for additions

ou can make to the programs in
this book or to your own programs.
In most cases you won't be able to
add these to a ZX81 with only 1Kas
e games themselves fill almost all
its memory space, but you should
find there is plenty of room onthe
other computers.

Remember you will either have to
»strict your additions to the spare
line numbers in a program or
renumber the program. lf you
lecide to renumber, take care you
hange all the GOTO and GOSUB

es too. 1000 PRINT "PRESS A KEY TO CONTINUE ";
| MS ZxIO1O IF INKEY$<"" THEN GOTO 1010

i 41010 [I$<-GET$

Getting the computer to tellyou  eioin GET 1s

| ow to play AlOJ]O GET I%$ z IF I%$-"" TMHEN GOTO 1010

1020 PRINT
Youcanadda A
on to any
program to make
ihe computer print
nstructions telling
you what to do. The
žaSlest way to do d
this is to add some lines, such asthose
below, at the beginning ofthe

zale and then put a sub-routine at
he en

If your instructions are very long, you
may want to insert this sub-routine
which stops the program runningata
particular point until you press a key.
This way you can stop the instructions
scrolling off the top of thescreen
before you have read them. Puta
GOSUB lineat the place you wantthe
program to stop and then put this sub-
routine at the end.

Making the computer '"'talk"' to

O PRINT "TITLE OF GAME"
stjo "DO YOU WANT TO"

NT "KNOW MOM TO De
ME a PLAY

7 JF I$(])2"Y" THEN GOSUR 1000

You can make the computer ask you

guestions and react to your answeris.

Ni ra o a O For instance, here is an addition which
; SUB 1060 vil] make the computer refuse to play

"eli program goes here

000 PRINT »

WHAT YOU -
debi PRINT "DO IS ME TE
?? RETURN

with you unless your name begins with J.

PRINT "WHAT IS YOUR NAME?"

INPUT 1$

IF I8(1)<>"J" THEN GOTO 1000

IF LEFT$(I$,1)<>"J" THEN GOTO 1000

(Ouc
an add as many print statements PRINT "OK-YOU CAN PLAY."
PRINT "ARE YOU READY?"

z Sal fOr the instructions, just
Ord ri tom mena zdne ciš< >"Y" THEN GOTO 5
ne. Restnct the am pi ofeach 4xMA07 IF LEFTS(Js$,1)<>"y" THEN GOTO 5
hside the | of the part
mk duotation marks to the
ele characters Your computer
On one line. Don't forgetto

Ši
SOAAMUN-—

maln program here

1000 PRINT "SORRY THIS GAME IS"

DRE TURN line atthe end orthe 1010 PRINT "ONLY FOR PEOPLE"
am 1020 PRINT "WHOSE NAMES BEGIN"
Wontwork. 1030 PRINT "MITH J"

Here is another one where the
computer dares you to be brave
enough to play.
lu PRINT "VERY SCAREY GAME"
12 PRINT "ARE YOU BRAVE ENOUGH"
14 PRINT "TO TACFHLE TME GREEN"
15 PRINT "HAIRY MONSTER?"
15 INPUT [$

S Zx1? IF 1$6/l)e"Y" TMEN GOTO 20

AMA0I7 IF LEFT$(I$,1)e"Y" TMEN GOTO 20

18 PRINT "COMARD"
19 STOP

You could combine this with the
instruction sub-routine by taking hnes
11 to 17 from the instructions section
on this page and putting them at lines
20 to 26 of this program. You canthen
start the malin program at line 30and
add the instruction sub-routine at the
end.

Would you like another go?

Instead of typing RUN each time you
play a game, you can makethe
computer ask you if you'd like another
go. Put these lines at the end ofthe
program, just before the last STOP
statement.

1000 PRINT "DO YOU WANT ANOTHER GO?"

1010 INPUT I$
S ZX1020 IF I$(1)e5"Y" THEN RUN
XxMA01O20 IF LEFT$(I$,1)e"Y" THEN RUN
1030 PRINT "OK THEN - BYE"
1040 STOP

Change line
numbers according
to your program.

Adding sound effects

The BBC, VIC 20, ZX Spectrum and
some Apples are able to produce
sounds and you can add lines to your
programs to make them do soat
appropriate places. You could addan
explosion for instance, ora little tune
which plays if you win. All the |
computers need different instructions
to make sounds though, so you will
have to look at your manual. In some

—m ne zn a o —

Noel kača s Č ie?

Cases you can add a single line to your
program at the place you want the
sound. In others, you need several
lines and it is best to put these in asa
sub-routine.
As an example, here is the sound of

a shot for the BBC. You canexperiment
with where to putit in the program, but
you must give it a line number to make
it work:

SOUND 0, 15,5,10

At the back of the VIC manual you
will find some useful sub-routines for
sounds such as "laser beam",
"explosion" and "red alert". Puta
GOSUB line where you want the sound
to appear, number the sub-routine and
add a RETURNAat the end ofit.

Special note for BBC and x
Spectrum users 4 X

If you have a BBC or a ZX Spectrum
you may find that some of the games
in this book run too fast for you. You
will find a box next to these games
containing instructions for

changing the speed. Remember, to
slow the game up you always need
to use a higher number. Later
models of the BBC may run upto
twice as fast as the earljer models,
and this could make the games
appear impossible on the first run.
Be prepared to make big changes
to the speed number to correci this.