This article is about the GEOS home computer operating system. For the PC/x86 based system, see GEOS (16-bit operating system).

GEOS (Graphic Environment Operating System) was an operating system from Berkeley Softworks (later Geoworks). Originally designed for the Commodore 64 and released in 1986, it provided a graphical user interface for the venerable 8-bit computer.

GEOS closely resembled early versions of Mac OS and included a graphical word processor (geoWrite) and paint program (geoPaint). For many years, Commodore bundled GEOS with its redesigned and cost reduced C64, the C64C. At its peak, GEOS was the third most popular operating system in the world in terms of units shipped, trailing only DOS and Mac OS.

Other GEOS-compatible software packages were available from Berkeley or from third parties, including a reasonably sophisticated desktop publishing application called geoPublish and a spreadsheet called geoCalc. While geoPublish was not as sophisticated as Aldus Pagemaker and geoCalc not as sophisticated as Microsoft Excel, the packages provided reasonable functionality, and Berkeley founder Brian Dougherty claimed the company ran its business using its own software on Commodore 8-bit computers for several years.

Enhanced versions of GEOS later became available for the Commodore 128 and the Apple II family (as well as a little-known version for the unsuccessful Commodore Plus/4—the machine that was originally meant to be the C64's successor).

Written by a group of programmers who cut their teeth on limited-resource video game machines such as the Atari 2600, GEOS was revered for what it could accomplish on machines with 64–128KB of RAM memory and 1–2 MHz of 8-bit processing power. And, unlike many pieces of commercial software for the C64/128, GEOS 128 took full advantage of many of the C128's add-ons and improvements, such as RAM Expansion Units (REUs), the enhanced-capacity 1571 (5¼") and 1581 (3½") floppy disk drives, and the high-resolution RGB display mode.

Via Berkeley's special geoCable interface converter or other third-party interfaces to connect standard RS-232 or Centronics printers to the Commodore serial bus, GEOS supported a wide variety of printers, including HP PCL printers and the Apple LaserWriter. This ability to print to high-end printers was a major factor in making GEOS a desktop publishing platform.

The Apple II version of GEOS was released as freeware (not open source) in August 2003. The Commodore 64/128 versions followed in February 2004.

References

• Farr, Michael (1987). The Official GEOS Programmer's Reference Guide. For Commodore 64/64C/128. Includes versions 1.0, 1.1, and 1.2. Bantam Books/Berkeley Softworks. ISBN 0-553-34404-8.
• Tornsdorf, Manfred; Kerkoh, Rüdiger (1986). GEOS Inside and Out. An introduction to GEOS, its applications and internals. Abacus/Data Becker. ISBN 0-916439-81-X.

External links

• The Commodore GEOS FAQ v1.4.2 – By Bo Zimmermann