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With the availablility of a myriad of easy to use Kernal calls, and a structure that lends itself to impressive graphical applications, GEOS is the ultimate in programming pleasure. To further the end of helping other 8-Bit programmers tackle this exciting environment, this page has been put together to support all of the major tools, to collect (and correct!) all of the major technical documents, and try to provide a central point for geoProgrammers to share their discoveries and accomplishments.

GEOS Kernal

The following documents are based off of Alexander Donald Boyce's GEOS Technical manual, which is available for download from many locations. However good this manual is, however, it contained numerous oversights and errors which require correction, a few deficiencies in the coverage of some subjects, and most of all, it required UPDATING. Here are some of the highlights of this document. The complete document is at a link at the bottom of the page.

GEOS Device Drivers

Device Drivers in GEOS are at once the most vital aspect of it's hardware independent abilities, and the most underdeveloped aspect of the Kernal. This can best be seen in BSW's failure to better implement disk device drivers. All the same, here is some information on using and programming the two device driver types under GEOS.

  • Input Device Drivers
  • Printer Drivers

    GEOS File Structures

    GEOS has introduced a number of new file types to take advantage of its picture and text clip, font, and other integrated abilities. From the deskTop, GEOS files include icons, creation time, author and description, and associated application information. All of this, and especially the unique VLIR type, require that the programmer learn a whole new style of file and directory control, explained below.

    Miscellaneous Notes

    Here are some notes on assorted topics on writing applications in GEOS

    Miscellaneous GEOS Dev Documents

    Here are the memory maps, character sets, error codes, etc that are just plain necessary to understanding and using the Kernal calls completely.


    GeoBASIC is an extremely powerful and easy to use development tool. Menus, icons, bitmaps, dialog boxes, etc are all easily buildable in this GUI environment. The ability to run programs before making applications, and built in tools for making menus, sprites, bitmaps, icons, etc. are all excellent. The language itself resembles the standard CBM BASIC we are so used to, and is an excellent high level language. However, GeoBASIC suffers from two fatal flaws: one is BUGS, numerous and serious. The other problem is memory. GeoBASIC allows only 7K for your entire application, including variables.

    Wheels Development Documents

    "Wheels 64" and "Wheels 128" are compatible upgrades to the original GEOS system by Maurice Randall that provided support for new hardware as well as an upgraded deskTop (called Dashboard) with support for more devices, subdirectories, and moveable windows. While there was never an official developers guide released, emails were exchanged, and Mr. Randall was very helpful about sharing his knowledge. Below is a link to a pdf containing a scan of the pages from the print-outs of those notes. Since it contains nothing but images, it is LARGE.

    Complete GEOS Technical Reference Manual

    Complete geoBASIC unofficial Manual Addendum

    Complete Hitchiker's Guide to GEOS (rev 2022)

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