“BASIC Zgrass—a sophisticated graphics language for the Bally Home Library Computer” by DeFanti, Fenton and Donato

  • ©Thomas (Tom) A. DeFanti, Jay Fenton, and Nola Donato




    BASIC Zgrass—a sophisticated graphics language for the Bally Home Library Computer



    Home computer users are just now discovering computer graphics. Modest extensions to BASIC allow plotting but not much more. The Bally Home Library Computer, however, has hardware to aid implementation of video games. Custom integrated circuits working on a 160×102 pixel (2 bits per pixel) color television screen allow certain forms of animation in real time. To give this power to the user, BASIC Zgrass has been designed and implemented. It is an extension of BASIC that allows parallel processes, picture objects that move, scale and group together as well as several drawing modes. There are also software controls of a three-voice music synthesizer, interactive input devices, a film camera and an IEEE bus interface. We will concentrate mainly on the language design for making it all easy to learn and use.


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