Original 1987 spiral-bound manual titled 'The Official GEOS Programmer's Reference Guide' by Berkeley Softworks and Michael Farr, published by Bantam Books. Designed for Commodore 64/64C/128, this guide covers GEOS versions 1.0, 1.1, and 1.2. Features a black cover with colorful pixel icons and visible shelf wear on corners. ISBN 0-553-34404-8. Author: Michael Farr. Format: Spiral-bound. Language: English.