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BLITZKRIEG - Docs sheet for the 32k Apple ][
Programmed by Mark Cross for Programma -- 1980
Compiled by Paula (I also fixed hex typos in original Programma doc)
Rev.3/1981
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Cassette loading address from monitor: 200.4000R then 800G to run.
GAME PLAY
---------
Use the paddle or keyboard to aim your anti-aircraft gun and shoot down the
enemy planes! Bombers and three kinds of fighters fly overhead. If a plane
flies into another plane's debris, it will explode. Some pilots are inept
and fly into other planes, causing you to gain points! And the debris from
that crash could gain you more free points! And so on...
The game ends when your gun runs out of bullets, or one of the bombers drops
a bomb close enough to your gun to blow you up.
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MEMORY USAGE
------------
$0000-0011 - Temporary storage
$0800-0B16 - Slightly modified Apple hi-res routines
$0B19-254F - Main program
$38D0-3FFF - Shape table
$4000-5FFF - Hi-Res screen memory
MODIFICATIONS
-------------
The game has several adjustments to customize it to each user. These have been
pre-set, but can be changed as discussed below. Do this for each change:
1) - Load the program.
2) - In Integer Basic (or the monitor), make the changes. The Blitzkrieg
program occupies the same place in memory as Applesoft programs. It
is possible to load, modify and run Blitzkrieg only if there is NO
Applesoft program!
3) - Optional: Resave the new version of the game:
To tape from monitor: 200.4000W
From DOS: BSAVE BLITZKRIEG, A2048, L14336
Run it with CALL 2048 -or- 800G from the monitor
SPEED
-----
The program asks you whether you want to modify some things before starting.
This gives you a chance to set the speed. Asking for speed 9 makes the game
run as fast as possible. It also makes your score higher.
COLORS
------
The background is originally black, and the scene is drawn in white. These
colors can be reversed when the program gives you a chance to make
modifications.
NOISES
------
The debris makes sounds as it flies through the air. This sounds like
cracking, buzzing, or a steady tone depending on the speed of the game.
The noise can be disabled by POKEing zero into locations 6960 and 6961
($1B30 and $1B31). Restore the noises with POKE 6960,48 and POKE 6961,192.
AMMUNITION
----------
The starting ammo is set at 100. It can be increased by POKEing a number
up to 255 ($FF) into location 3148 ($C4C).
NEAR MISSES
-----------
Some anti-aircraft shells have proximity fuses that explode if they get close
to a plane. The shells in this game have the same ability. If they get close
to a plane, then the plane will blow up. The closeness required is a number
in location 4064 ($FE0). This number is originally 5. It can be decreased to
1 for a hard game, or increased to 8 for an easier game.
NUMBER OF AIRPLANES
-------------------
A new plane is created about once every 32 internal program time units. The
frequency of new planes can be adjusted by POKEing a number into location
5419 ($141D). This number is originally 31 ($1F).
Try changing it to these numbers:
7 ($07) = Four times the original number of planes
15 ($0F) = Twice the original number of planes
31 ($1F) = Original number of planes
63 ($3F) = Half the original number of planes
Other numbers will make the planes come in irregularly spaced groups.
DIRECTION OF FLIGHT
-------------------
One-fourth of the planes fly from right to left, permitting collisions. You
can make all the planes fly from left to right by POKEing the number 224 ($E0)
into locations 5175 thru 5179 ($1437 thru $143B).
-= Individual Plane Speeds =-
Plane Type Location Original Speed
---------- ---------- ---------------------
Rightward Bomber 5210 $145A 4
Rightward Big Fighter 5218 $1462 6
Rightward Med Fighter 5226 $146A 6
Rightward Small Fighter 5230 $146E 5
Leftward Bomber 5293 $14AD -4 (Hex) = 252 Decimal
Leftward Big Fighter 5301 $14B5 -6 (Hex) = 250 Decimal
Leftward Med Fighter 5309 $14BD -6 (Hex) = 250 Decimal
Leftward Small Fighter 5313 $14C1 -5 (Hex) = 253 Decimal
NUMBER OF BOMBERS
-----------------
You can control the types of airplanes using the "M" option when the program
starts. Bombers are very easy to hit, but too many bombers will make it hard
to avoid getting bombed.
NUMBER OF BOMBS DROPPED
-----------------------
A bomb is dropped by some bombers every 4 program time units if there is a
bomber on the screen. This can be changed. POKE a new number into location
5338 ($14DA). The number is 3 originally. A larger number will get you fewer
bombs. The number POKEd into this location must be a member of the series
3, 7, 11, 15, 19, 23, 27, 31,... Example: POKE 5338,255 ($14DA w. $FF) will
nearly disable the bombers for a young child who can't take the tension in
the original game.
DEBRIS
------
Sometimes the screen gets too full of debris. The amount of debris per ex-
plosion is controlled by the number 254 ($FE) stored in location 6174 ($181E).
Less debris would make a faster game.
252 ($FC) = No debris at all
253 ($FD) = 5 dots per explosion
254 ($FE) = 10 dots per explosion (original game value)
255 ($FF) = 15 dots per explosion
0 ($00) = 20 dots per explosion
1 ($01) = 25 dots per explosion
2 ($02) = 30 dots per explosion
HIGH SCORE
----------
The previous high score is stored in locations 2901 and 2902 ($B55 and $B56)
inside the program code. It is automatically saved along with the program. If
this number ever gets impossibly high, you can reset it. The simplest reset is
to POKE a 0 into both locations 2901 and 2902.
SHAPE TABLE
-----------
An Apple format shape table of 136 shapes is stored in locations 14544 ($38D0)
through 16383 ($3FFF). The shapes are listed below. All of the printing
characters (1-8, 21, 32-127) are in a 5x7 matrix with the shape starting at
the upper left corner of the drawing. The other shapes start drawing in their
center.
Shapes
------
1 - Box - 5 wide x 7 high
2 - Solid 5x7 rectangle - draws black to erase something.
3 - Arrow - Upper right
4 - Arrow - Straight up
5 - Arrow - Lower left
6 - Arrow - Upper left
7 - Alpha
8 - Arrow - Straight left
9 - Rightward bomber
10 - Rightward big fighter
11 - Rightward medium fighter
12 - Rightward small fighter
13 - Leftward bomber
14 - Leftward big fighter
15 - Leftward medium fighter
16 - Leftward small fighter
17 - Airplane seen from above #1
18 - Airplane seen from above #2
19 - Airplane seen from above #3
20 - Very small tank (can be magnified and rotated)
21 - Rightward arrow
22 - Slightly larger gun
23 - 2x2 square
24 - Plus
25 - 6x6 diamond - solid
26 - 7x7 ball
27 - Tie Fighter
28 - X-wing fighter
29 - 5 unit horizontal line
30 - 5 unit vertical line
31 - 6 pointed star (explosion)
32 - Blank space
- ASCII Characters -
33 - ! 69 - E 105 - i
34 - " 70 - F 106 - j
35 - # 71 - G 107 - k
36 - $ 72 - H 108 - l
37 - % 73 - I 109 - m
38 - & 74 - J 110 - n
39 - ' 75 - K 111 - o
40 - ( 76 - L 112 - p
41 - ) 77 - M 113 - q
42 - * 78 - N 114 - r
43 - + 79 - O 115 - s
44 - , 80 - P 116 - t
45 - - 81 - Q 117 - u
46 - . 82 - R 118 - v
47 - / 83 - S 119 - w
48 - 0 84 - T 120 - x
49 - 1 85 - U 121 - y
50 - 2 86 - V 122 - z
51 - 3 87 - W 123 - {
52 - 4 88 - X 124 - Vertical line
53 - 5 89 - Y 125 - }
54 - 6 90 - Z 126 - ~
55 - 7 91 - [ 127 - Left arrow
56 - 8 92 - \ 128 - Small 4x4 ball
57 - 9 93 - ] 129 - 7x7 open circle
58 - : 94 - ^ 130 - 11x12 open circle (tree-top)
59 - ; 95 - Underline 131 - Gun in airplanes game
60 - < 96 - Single quote 132 - Race car #1
61 - = 97 - a 133 - Race car #2
62 - > 98 - b 134 - Bomb with partial tail fin
63 - ? 99 - c 135 - Rocket
64 - @ 100 - d 136 - Falling bomb
65 - A 101 - e
66 - B 102 - f
67 - C 103 - g
68 - D 104 - h