Biker Dave
David Schwener
Here's a game guaranteed to bring out the daredevil in any computer owner. The original version of "Biker Dave" is written for Atari 400, 800, XL, and XE computers. We've added new translations for the IBM PC/PCjr, Commodore 64, and Amiga. The Commodore 64 and Atari versions require a joystick.
As the ramp nears, you focus your mind, tighten your grip on the handlebars, and accelerate the motorcycle for the final approach. The deep, throaty cry of your machine's powerful engine drowns the spectators' cheers, and the onrushing wind pushes against your body like a gigantic hand. If your speed and timing aren't exactly right, you may overshoot the ramp and lose control, or fall short into the line of cars.
Will you earn fame by surviving the jump or tumble into anonymity with a cartwheeling crash? As your speed mounts and the sidelines fade into a blur, there's no more time to wonder and no chance to turn back. Only the utmost in coordination and skill will bring you safely to earth on the other side.
"Biker Dave" is a realistic computer game that simulates the thrills and challenge of motorcycle acrobatics. Type and save the program listed for your computer, and be sure to read the general game instructions as well as the specific notes for your machine.
Over The Ramp
Biker Dave begins by asking you to select one of the two available skill levels: The rookie level is easier than the pro level. With this preliminary out of the way, the program displays the game screen. In the upper left corner of the screen is the garage where you begin the ride. The rest of the screen contains the racetrack, with a couple of tunnels along the way, and a formidable obstacle which consists of several autos flanked by launching and landing ramps. Press the joystick button to accelerate the bike. Your goal is to ride down the track, through the tunnels, and toward the final obstacle, gaining just enough speed to jump over the cars without crashing.
That may sound easy, but it's not as simple as you might think. For one thing, your bike is a specially built stunt machine with no brakes. Should you reach too high a speed, there's no way to slow down again. And if you accelerate too fast, the bike rises up into a wheelie. That's not bad in itself, but if you accelerate too hard from a-wheelie position, the bike tips backwards and crashes.
As you approach the launching ramp, you need to go just fast enough to clear the parked cars, but not so fast that you lose control and miss the landing ramp on the other side. A successful jump requires precise timing and sure control of the throttle. The score you earn depends on the number of cars jumped and the number of attempts you made at that level.
Each time you jump over the cars, the racetrack crew moves the launching ramp and adds another car to the lineup. Unfortunately, the crew is somewhat unreliable and has been known to change the launching ramp's angle slightly when moving it. Thus, even though you may have jumped three cars with a speed of 100 miles per hour, there's no guarantee that the same speed will work every time.
At the pro level you must also jump a large hoop midway through the course. The hoop has a launching ramp, but no landing ramp. Each time a car is added to the final obstacle, the hoop's launching ramp moves farther away, as well.
Atari Version
This version of Biker Dave is written entirely in BASIC and runs on Atari 400, 800, XL, and XE computers. A joystick is required; plug it into port 1 before you run the program.
This program employs several techniques to compensate for the slowness of BASIC. Lines 1470–1610 position the P/M (Player/ Missile) graphics at the same address as the string P0$. When a player/missile needs to be moved or changed, this string is modified with BASIC string commands. Lines 1650–1700 read various bike images into separate strings, which are later made part of P0$. Since the ramp images don't change, they are read directly into memory.
When the bike enters or exits the garage and tunnels, it goes in front of the blue opening, but behind the yellow or green walls. Similarly, the bike jumps through the hoop by going in front of the red portion, but behind the green. Line 1710 prepares for these three-dimensional graphic effects by putting a special value in the priority register (location 623).
Although the bike travels right, left, and then right again, the program itself doesn't follow that flow. The code that performs the actual jump is located near the beginning of the program. Since lines with low line numbers run faster, this insures that the speed-critical portions of the program work as quickly as possible.
Commodore 64 Version
A joystick is required to play the 64 version of Biker Dave (Program 2), which includes a flaming hoop midway through the course. Plug the joystick into port 2 before you run the program. To accelerate the bike, hold down the joystick button. There is no rookie level in this version; the game ends when you crash your last bike or succeed in jumping nine cars at once.
IBM PC/PCjr Version
The IBM PC/PCjr version of Biker Dave (Program 3) requires cartridge BASIC for the PCjr, or BASICA and a color/graphics card for the PC. Press the space bar to accelerate the motorcycle. One skill level is provided; the game ends when you succeed in jumping nine cars at a time or run out of bikes.
Amiga Version
In this version of Biker Dave (Program 4) the left mouse button controls your speed. (Avoid the right button; pressing it may crash the program.) The game has no rookie level; it ends when you manage to jump nine cars at once or crash your last bike. You may wish to adjust the speed at which the left button responds by using the Preferences tool from the Workbench.
For instructions on entering these listings, please refer to "COMPUTE!'s Guide to Typing In Programs" in this issue of COMPUTE!.
