Ñ                       SPEED BY RICHARD MARTIN

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§
Hello Again WAC readers. In this article I  am going to give you a few
pointers onto the problems I have  occured  and  how I got around them
and some of the useful methods of programming games.

This is an old chestnut for all  AMOS  users. How to get your programs
to run fast. Well to start with  I`ll start off explaining WHY AMOS is
slower than Blitz 2 normally.  AMOS  is an interpreted laungage. Blitz
is compiled. BASIC  is  in  many  respects  simular  to a conventional
laungage such as Latin  or  English.  The  most skilled programers can
read a computer laungage as if it  was  English! So Imagine you are in
France and know no French. But you do have a French translation guide.
A French man comes up to you and says "Bonjour Monsieur!". If you knew
no French you would have  to  look  it  up.  AMOS  is like this. Every
command you tell it do it converts  it machine code. It TRANSLATES it.
A compiled laungage is the same as someone spending a while learning a
laungage and then when someone asks  them  a question they can respond
instantly. But  I  am  not  trying  to  get  you  all  to  buy  Blitz.
(personally I Hate  Blitz)  but  it  means  that  these  AMOS vs Blitz
comparisons are a little biased.  AMOS  has  a compiler which lets you
protect your source and lets AMOS LEARN your program.
¦
Anyway, away from the lecture. There are some ways to speed up your
program even when it is interpreted.  The  first is to update parts of
your program that do not to be checked every loop fewer times. Type in
these examples that follow and see what happens.

` SLOW EXAMPLE.
CLS 0
INK 2,0,0
BOX 50,50 TO 75,75
GETBOB 1,50,50 TO 75,75
INK 6,0,0
CIRCLE 100,100,25
GETBOB 2,75,75 TO 125,125
`
SCORE=0
X=0
Y=0
DOUBLE BUFFER
BOB 2,RND(320),RND(200),2
DO
IF JUP(1)
Y=Y-1
ENDIF
IF JDOWN(1)
Y=Y+2
ENDIF
IF JLEFT(1)
X=X-1
ENDIF
IF JRIGHT(1)
X=X+1
ENDIF
IF BOBCOL(1,2 TO 2)
BELL
INC SCORE
BOB 2,RND(320),RND(200,2
WAIT VBL
END IF
INK 0,0,0
BAR 0,0 TO 100,12
LOCATE 0,0
PRINT SCORE
BOB 1,X,Y,1
WAIT VBL
LOOP
Ï
You will notice that the above  example  is  dreadfully slow and it is
nearly impossible to get the square to touch the circle. Now add these
lines.

just after the Do Add:

INC COUNTER

And before Ink 0,0,0 add the extra lines so it looks like.

IF COUNTER=10
INK 0,0,0
BAR0,0 TO 100,12
LOCATE 0,0
PRINT SCORE
COUNTER=0
END IF

Now rerun the program. It should update 5 times a second and be faster
than it was before. In updating the score  we can go a step further by
only updatinging it when there is a  change  in it. But I have not the
time or space ( I am not sure how much text Pauls Engine lets a doc be
in length) so I`ll explain in  the  code.  They  should be on the disk
label SPEEDEX1.AMOS ,SPEEDEX2.AMOS and (you guessed it) SPEEDEX3.AMOS.

I hope to continue this article if Paul will let me.

Richard Martin.