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GEOS™ (Graphic Environment Operating System) is the most popular alternative operating system for the C64. It was developed by GeoWorks (formerly Berkeley Software) in 1985-88 and was for many years distributed by Creative Micro Devices. Since Mid 2001 it is distributed by "Click Here Software" (http://www.cmdrkey.com). It is available free of charge for non-comercial use at http://cbmfiles.com/geos/index.html.

GEOS offers a graphic user interface with menus, dialog, windows just like the MacOS (and its imitations GEM for the Atari ST and AmigaOS for the Commodore Amiga). Many programs using this consistent look and feel have been written for GEOS. They are easy to use and are (for their age) extremely powerful. Due to the graphic user interface it is even possible to have WYSIWYG on a C64.

To make GEOS as easy to use as possible several GEOS-specific optimizations have been included in Power64 (details see below). In case these optimizations should prove to cause trouble, they can be disabled via Options/ROM Patches/GEOS Support.

There are many different versions of GEOS and lots of GEOS applications. It was of course not possible to check all possible combinations with Power64. The development of the optimizations took place using GEOS 2.0 running geoWrite, geoPaint and several other applications. There is no warranty that every combination of GEOS version and GEOS application will work without crashing GEOS.

8.1 Disk-Access in GEOS

GEOS uses its own fastloader to accelerate disk access. Of course this fastloader does only slow down things in an emulator, and therefore Power64 circumvents the GEOS' disk access code as much as possible. In general GEOS works with Power64 without the need for Complete 1541 Floppy Emulation. The complete emulation is only rarely necessary and even then the common disk operations (block read/write) are drastically accelerated. So: If GEOS crashes for you (especially while booting) try turning on Complete Floppy Emulation.
GEOS also works fine with 1571 and 1581 disk drives, but it needs to be told what type of drive is available at what device number (using the CONFIGURE program). Furthermore care should be taken not to change the type of disk drive used in the middle of running GEOS (Remember: This is emulation of real hardware. It is impossible to convert a 1571 to a 1581 on the fly in real hardware, therefore GEOS does not expect such an thing to happen, even if it is easy in emulation). If you use a mixed set of drives GEOS will want to read the new disk driver every time you switch to another disk. This driver (also stored in the CONFIGURE file) needs to be available on the (old) currently active disk. This really means that it has to be on every disk (or you switch drive types once, and from then on only use drives of that type).

8.2 Mouse-Control in GEOS

GEOS is best used with the mouse. It is possible to use it with a joystick or even the keyboard, but these are only work-arounds for the majority of C64 users who do not have a mouse.

In Power64 the Mac mouse is used to emulate the C64 mouse. When the Mac mouse is over the GEOS window, the Mac arrow mouse cursor is replaced by crosshairs (so that the Mac cursor remains visible even if GEOS turns off its cursor) and the GEOS mouse cursor is used to indicate the mouse position. The GEOS mouse moves with the Mac mouse, even if the Mac mouse is outside the GEOS window, but, to avoid unwanted activity, Mac mouse clicks are not translated to GEOS mouse clicks in this situation.

Sometimes GEOS repositions its mouse (e.g. to place the mouse cursor in the top entry of a menu after clicking the menu header, or near the OK button of a dialog). In such situations Power64 does (against all Apple Human Interface Guidelines) move the Mac mouse along. If this behavior is very annoying (e.g. because GEOS tries to lock up its mouse in the Cancel button of the printing dialog), the connection between C64 and Mac mouse can be suspended by holding down the Command key.

8.3 Printing in GEOS

GEOS offers a standard printing interface to its applications. This is a dramatic improvement over the general practise of that time, where every application had to provide its own interface for every printer that it wanted to support. Now only GEOS itself requires a specific printer driver for every supported printer.

Power64 comes with two printer drivers for GEOS: Quickdraw B/W and Quickdraw Color. While Quickdraw B/W emulates a normal (black) printer, Quickdraw Color offers color printing. To use the GEOS printer drivers copy them from the GEOS Printer Driver Disk to (a copy) of your GEOS Boot disk and onto every disk from that you wish to print. Once that is done, you can install the printer in GEOS using the menu item GEOS/Select Printer in the GEOS desktop.

Both GEOS printer drivers of Power64 redirect the output to files in the Printer-Folder (see 5.15 Printer). Due to the internal design of the GEOS printer control, every page of output will be written to a separate file. GEOS offers 3 levels of print quality in its printer dialog: High Quality (the default mode) prints its screen as bitmaps, so that all images, fonts and colors can be printed. Thus printouts are stored as bitmaps (b/w or color depending on the chosen printer) in the print files - Thus all visual information is conserved, but it is impossible to use a text editor to search for strings. Alternately you can use Draft printing mode. This discards all formatting and stores the text in ASCII format, making it easy to import the files any Mac word processor. There is also NLQ (Near Letter Quality) printing, but this is not supported by Power64 and creates unusable text files without any inter-word spacing.

8.4 RAM Expansion in GEOS

GEOS is one of the few Commodore 64 applications that is able to use a RAM expansion. It is advisable to add a RAM expansion to the C64 before loading GEOS (via Devices/RAM Expansion) and to advertise it to GEOS using the GEOS Preference Manager.

8.5 Date and Time in GEOS

GEOS uses the Real-Time clock of CIA#1 to keep track of the current time of day and also knows the current date. These informations are displayed on the GEOS Desktop and are also (via a modified file floppy disk format) stored for every file.
Power64 automatically adjust the day of time according to the Mac system clock. Beware: GEOS is not year-2000 compliant. The year is stored as 8-bit binary number since 1900 (which would make it possible to count up to year 2155) however after 1999 GEOS will still jump back to 1900.
After loading a RAM Image of GEOS the time and date are immediately adjusted, but GEOS does not display the date correctly at once. The new date is only displayed after the screen has been (e.g. after closing an application) completely redrawn.

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