Eight-bit Commodores will never be the same again.

A desktop user interface, including pull-down menus, dialog boxes and proportionally spaced fonts, is the exciting visual hallmark of GEOS, the new Graphics Environment Operating System for Commodore 64,64c and 128 personal computers. Underlying this is a host of other features that will revolutionize the way people use and program the Commodore 64 series.

Applications developed under this new programming environment will have multitasking capability and faster disk access, and can be more data intensivebigger than previously thought possible for this machine. Developers who take advantage of these features will be able to save valuable time while increasing the quality of their applications.

However, developing applications for GEOS will require proficiency in event driven programming—a method with which most Commodore programmers are not yet familiar.

Written by Berkeley Softworks, the creator of GEOS, The Official GEOS Programmer's Reference Guide is definitive reference material for those who program under this new environment. This book provides you with all commands,
memory maps, and other pertinent reference materials needed to successfully program in this new environment, and describes in detail the input and printer drivers for some of the more popular devices. Learn everything you need to know about GEOS, including:

• Hi-Res Bit-Map Mode—Redefining the Commodore 64 screen for GEOS.
• Display Buffering—Managing the screen display under tight memory constraints.
• Input Drivers—Using the mouse to control your program.
• Variable Length I ndexed Record (VLIR)—Breaki ng u p files i nto records to speed up data movement.
• Disk Turbo—Speeding up disk access time for better memory control.
• All this and much more.