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!Pal256
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1995-11-13
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Instructions for !Pal256 by Andrew Sellors
*****************************************************************************
* NOTE: *
* !Pal256 is FreeWare. *
* This means that you may freely copy and distribute it, provided that it *
* is complete with all original files, and that you do not sell it. *
* PD libraries may charge a nominal fee for the cost of duplication, *
* postage etc. *
* In no circumstances shall the author be liable for any damage, loss of *
* profits, time or data or any indirect or consequential loss rising out of *
* the use of this software or inability to use this software. *
*****************************************************************************
Contents:
~~~~~~~~~
About Pal256
Compatibility
256 palette entry modes
Operation
Flickering Screens
Configuration
Contacting the author
********************************************************************************
About Pal256:
~~~~~~~~~~~~~
* Pal256 programs the VIDC20 palette when in 256 entry mode to a selection of
predefined palettes:
* 256 greyscale palette. (for viewing 256 greylevel images)
* standard 256 colour palette.
* greyscale palette with 8 WIMP colours (for viewing 256 greyscale images
whilst retaining the normal WIMP colours)
* Pal256 also loads 256 colour palette files (as saved by !Paint) and sets
the screen palette to that.
* The defined palette is always retained, see "flickering screens" below
********************************************************************************
Compatibility:
~~~~~~~~~~~~~~
This program is for RISC OS 3.50 or later.
********************************************************************************
256 palette entry modes:
~~~~~~~~~~~~~~~~~~~~~~~~
Unlike the VIDC1 used in previous machines, the VIDC20 has 256 palette registers
which allows each colour in 256 colour modes to be defined as any value out of
the possible 16.7 million colours supported.
When a 256 colour mode is selected the VIDC20 is put into VIDC1 compatibility
mode where it emulates the 16 palette registers present in that chip. To select
256 palette register mode the 256 greys mode needs to be selected from the
Display Manager menu.
********************************************************************************
Operation:
~~~~~~~~~~
Starting up
===========
The !Pal256 application starts up when you double-click on its filer icon.
On startup the default palette is programmed if the current mode has a 256 entry
palette.
Selecting palettes
==================
Different palettes can be selected from the iconbar menu. The palette will only
be changed when in a 256 palette entry mode.
Saving the options saves the currently selected palette to be used the next time
the program is loaded.
If a palette file is loaded then the "Loaded File" option will be present,
otherwise it will be greyed out. When a palette file has been loaded it will
be available by selecting the "Loaded File" option until a new palette file
is loaded.
Loading palette files
=====================
A 256 colour palette file can be loaded by dragging its icon to the !Pal256 icon
on the icon bar. Only 256 colour palette files can be loaded, trying to load one
of the old Wimp palette files saved by the Palette Utility from RISC OS <= 3.1
results in an error being reported.
Once loaded, the screen palette is programmed with the colours from the file
and the "Loaded File" option on the menu is selected.
Using Pal256 with !Paint
========================
!Pal256 can be used to program the palette to the correct colours when viewing
a 256 colour image in !Paint.
Press Menu over the image and drag the palette file from Save=>Palette=>Save as
save window to the !Pal256 icon on the iconbar. The screen will be rebuilt
and !Paint will display the image with the correct colours.
********************************************************************************
Flickering Screens:
~~~~~~~~~~~~~~~~~~~
When in a 256 palette entry mode, the WIMP tries its hardest to program the
palette back to being the standard 256 greyscale. If the screen flickers with
certain operations, particularly when a task is exiting, this is due to !Pal256
re-programming the palette back after the WIMP has changed it.
********************************************************************************
Configuration:
~~~~~~~~~~~~~~
The Configure submenu off the iconbar menu allows:
* the currently selected options to be either saved and so used the next time
the program is loaded.
* the saved options loaded
* the palette setup window opened.
Saving the configuration saves the settings in the "Palette Setup" window and
also the currently selected palette.
If the "Loaded File" palette is selected when the options are saved then the
default of the "256 Colours" palette is saved.
"Palette Setup" window
======================
The palette setup window defines what the program does when it changes the
palette.
The default setting ensure that the OS and all running programs are informed
of the change in palette and the screen rebuilt correctly.
********************************************************************************
Contacting the author
~~~~~~~~~~~~~~~~~~~~
I, Andrew Sellors, can be contacted either at
57 Boundaries Road
Feltham
Middlesex
TW13 5DR
England
Or via Internet email at
asellors@orac2.demon.co.uk
Any feedback from users (bugs reports, requests for new features, praise,
money etc.) is gladly received.