The shared use of the microprocessor chip in the ZX-80 for computation and screen display makes continuous graphics difficult. The screen flashes whenever you input information, an effect that may be considered undesirable in a game.
The Amazing Active Display is a hybrid program containing machine language in a Basic program. The machine language routine allows a continuous display on the screen. In the program, a machine language program, stored as hexadecimal code, is converted into decimal numbers and POKEd into the computer’s memory. The machine code includes calls to several ROM routines, but bypasses the blanking of the screen.
This program is intended for use in your own application programs, for uses such as animated graphics, games requiring updates to the screen, instrumentation, and debugging. You can provide a programmable pause in a Basic program with a screen display.
Breakout is a game program using the Amazing Active Display, and shows what can be done with the program. It also comes as a Basic program with the display routine listed as Hex characters.
With real time action and challenge, Breakout is one of the best games yet available for the ZX-80. There is a continuous display at the top of the screen of a wall of blocks, and a graphics block bouncing up and down with a smooth continuous motion. The player must move a paddle at the bottom of the screen using the arrow keys (5 and 8). Each time the moving ball hits a block at the top of the screen, that block is removed. If you miss the ball with the paddle, you lose it. Once you manage to clear all the blocks off the screen, the ball bounces aimlessly around. There is no victory routine.
There are several weak points in the game. There is only one speed for the ball, no variations of the basic game, and no provisions for score keeping. The only way to stop the game is to unplug the computer. The Break key does not function. The instructions are quite minimal, and it may be difficult to understand the program well enough to use it in your own programs.
We like both programs, and enjoyed playing with them.
The Amazing Active Display ($20/£10)
Breakout ($20/£10)
K. MacDonald
26 Spiers Close
Knowle, Solihull West Midlands, B93 9ES
Great Britain