posted by Kroc on Thu 24th Aug 2006 20:26 UTC

"GEOS, Page 7"

4. Configuring GEOS

4.1 Hardware

GEOS must be told which drives you have connected. Double-click on the 'CONFIGURE 2.0' icon on the deskTop and you are presented with a simple screen with options for the different types of drives. CONFIGURE 2.0

Here, two disk drives are attached and a 512 KB RAM expansion. The 'shadowed' option appears so that you can use the RAM expansion to facilitate disk copying and speed up GEOS. (Not that this is a problem in an emulator, but the disk drive could be very slow at times). It is a known problem that a hardware bug ended up in the read speed of the disk drive being much slower than it should be. Programmers relied on 'fast-loaders', essentially decompression software loaded into the disk drive's RAM & CPU, to speed things up again.

4.2 UI Customisation

The application 'preference mgr' on the first page of the GEOS boot disk allows you to customise some basic UI Settings. preference mgr

The sliders allow you set mouse acceleration and speed. If you were not the proud owner of a mouse for your C64 (hands up those who had a mouse for their PSX?) you were stuck using a joystick to navigate the UI.

The C64 has no built in battery and is unable to maintain the time between power resets. On a normal C64 you would have to (if you could be bothered) set the time every boot by selecting the 'Options' command menu and selecting 'set clock'. The emulator I am using (Power64) has excellent GEOS support and sets the clock for me. If you purchase a FD-2000 floppy disk drive or RAM-Link cart from CMD, you could also add an optional extra to the configuration - a real time clock chip, allowing GEOS to keep accurate time. Custom icon

Interestingly, GEOS lets you edit the mouse pointer directly in a fashion very similar to how you could change the desktop pattern on the original Mac. Colour!?

The small squares next to 'Border', 'B.Ground', 'F.Ground' and 'Mouse' can be clicked to cycle the colours (out of the 16 available) for that element.

If this is supposed to be a monochrome UI, how is it doing the colour here? As stated before, the mouse (and those sliders) are hardware sprites, composited over the monochrome bitmap data, but the C64 has more tricks up its sleeve.

Though the bitmap data in memory is monochrome, the C64 could set the background and foreground colours to draw the bitmap with. Here as the light grey and dark grey combo of GEOS.

The font menu

In addition to this a 1 KB section of upper memory representing a 40x25 character gird let the computer assign changes to the chosen monochrome colours in each 8x8 pixel character.

The Preferences Manager 'Window' effectively aligns perfectly within the 40x25 grid of characters, so that the colours underneath could be changed using the colour map. The one byte that represents the colour under one of the 8x8 pixel characters is divided into two nybbles of 4-bits. Each of these nybbles can store a number from 0-15, representing the 16 available colours, and thus the Foreground and Background colours to use for the graphics in that character square.

Table of contents
  1. "GEOS, Page 1"
  2. "GEOS, Page 2"
  3. "GEOS, Page 3"
  4. "GEOS, Page 4"
  5. "GEOS, Page 5"
  6. "GEOS, Page 6"
  7. "GEOS, Page 7"
  8. "GEOS, Page 8"
  9. "GEOS, Page 9"
  10. "GEOS, Page 10"
  11. "GEOS, Page 11"
  12. "GEOS, Page 12"
  13. "GEOS, Page 13"
  14. "GEOS, Page 14"
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