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SECRET OF SEUCKCESS
BY JON WELLS - PART 3

Shortcuts
Part one | Part two | Part three
MAJOR LOCATIONS | PLAYER OPTIONS | SCORES AND ROUTINES | I LIKE TO SCORE
High-score listing 1 | High-score listing 2 | High-score listing 3

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All the listings

This article was first published in Commodore Format issue 45.

If you've got the Shoot-'Em-Up Construction Kit you've got a programming tool that makes writing vertically scrolling blasters a doddle. But getting it to produce really good vertically scrolling blasters takes more skill. Stick with Jon Wells, though, and you'll develop the skill.

Blimey, I bet you're thinking, look at all those figures. Let's skip this. But hold on, because these tables are your key to complete control when it comes to setting up in-game features in SEUCK games. This time we're going to look at the memory map which features the locations of some large chunks of game code, as well as the all-important in-game values you'll find within SEUCK. For instance, if you wanted to change the amount of lives player one has, you'd just POKE the new value into the memory address you'll find in the following tables.

MEMORY MAP 1 - MAJOR SECTIONS

There are also some very important locations dealing with the controls of the two players:

MEMORY MAP 2 - PLAYER OPTIONS

Extra important SEUCK addresses include:

MEMORY MAP 3 - SCORES AND ROUTINES

I LIKE TO SCORE

The player's score pointers are stored in a 6-byte series; from 24227-24232 decimal ($5EA3-$5EA8) for player 1, and 24233-24238 ($5EA9-$5EAE) for player 2.

To convert this into BASIC you can use the following routine:

HIGH-SCORE LISTING 1 (click to download the PRG file)

1 S1=0:S2=0:FOR A=24227 TO 24232
2 READ B:S1=S1+(PEEK(A)*B)
3 S2=S2+(PEEK(A+6)*B):NEXTA
4 PRINT"PLAYER 1 = ";S1:PRINT"PLAYER 2 = ";S2
5 DATA 100000,10000,1000,100,10,1

Note: this is how the listing appeared originally in Commodore Format, what follows below is an updated version directly from Jon himself - Andrew.

1 S1=0:S2=0:B=100000:FOR A=24227 TO 24232
2 S1=S1+(PEEK(A)*B):S2=S2+(PEEK(A+6)*B):B=B/10:NEXTA
3 PRINT"PLAYER 1 = ";S1:PRINT"PLAYER 2 = ";S2

If you are using a two-player game, then POKE 16578,0 or 1 starts a one or two player game respectively. Also, in one player mode, you may notice that pressing the fire button on player two's joystick results in no second player appearing.

When using this program, S1 and S2 refer to the two players' scores. You could use these figures to calculate a high-score table if you wanted to, using something a little bit like this:

HIGH-SCORE LISTING 2 (click to download the PRG file)

10 B=9:DIM H1(10),N1$(10): REM FOR 1 PLAYER
11 IF S1>>H1(B) THEN B=B-1:GOTO10
12 B=B+1:FOR A=9TOBSTEP-1:H1(A)=H1(A+1)
13 N1$(A)=N1$(A+1):NEXTA
14 H1(B)=S1:N1$(B)=NAME$

This might be a little difficult to follow, so let's go through the program line by line:

10 - Here we set up an array to hold 10 different names (N1$) and scores (H1)
11 - Next we compare our new score (S1) with the old ones (H1), to find out whether the next score in the table
        is higher than our new score (in Dave Golder's case, it's usually lower).
12 -
13 - These lines then move the scores and names down one position in the list,
         to make room for our new score.
14 - Finally we store the new name (NAME$) and score (S1) into the array.
        This name would be obtained by asking the user to enter it (as with just about any other game ever -
        what do you expect them to do, communicate with the game telepathically?).

The original scores and names would be set up first with DATA statements. The DIM in line 10 simply tells the computer to allocate memory to hold the values and names. If that all seems complicated, then here is an example of setting up the table:

HIGH-SCORE LISTING 3 (click to download the PRG file)

20 FORB=1TO10
30 READN$,S
40 H1(B)=S:N1$(B)=N$
50 NEXT B
55 FORC=1TO10:PRINTN1$(C),H1(C):NEXT
60 DATA "JON",50000
70 DATA "DAVE",40000
80 DATA "ANDREW",30000
90 DATA "WAYNE",20000
100 DATA "RICHARD",10000
110 DATA "ALLAN",5000
120 DATA "SHAUN",2500
130 DATA "NIGEL",1250
140 DATA "SIMON",675
150 DATA "PLAYER 1",0

Remember to put your names inside quotes so any spaces can be handled.
(This is an extra listing added by Andrew.)

That completes the three parts of the article originally published in Commodore Format, updated and edited here to remove some printing mistakes, and to place the debugged listings from part 3 into part 1.

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