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Create README.md
First short description of the display routine
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VBMP
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====
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BMP Viewer for the Apple II
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Introduction
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============
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This project is based on the work of Arnaud Cocquière and his hommage to Steve Jobs.
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http://www.ctrl-pomme-reset.fr/2011/10/11/hommage/
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Unlike most images shown on the Apple II, the image displayed is actually a BMP file
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without additional conversion. The disk includes the sources for the BMP viewer, so I
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decided to study it and learn a bit of 6502 assemmbly and graphics programming on the
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Apple II.
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Since my Apple IIc supports DHGR graphics I started playing with it to add support to
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16 color BMPs and monochrome pictures in Double High-Res. I thought this could be useful
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for someone else so I asked Arnaud for permission to publish it in GitHub.
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Usage
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=====
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The code uses the Merlin Assembler syntax. Just load it in Merlin on the Apple II and it
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should compile without problems.
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To load BMPs in the DSK Image I recommend Apple Commander, but Cider Press might do as
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well. Just import the BMP as a Raw binary file.
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Using Applesoft you can load the image with the following commands
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BLOAD IMAGE.BMP,A$4000
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BRUN DISPLAY
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Supported formats
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=================
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The viewer supports BMP Images with the following resolutions and color depths
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Monochrome (1bit color depth) 280 x 192 px
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Monochrome (1bit color depth) 560 x 192 px
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16 Color (4bit color depth) 140 x 192 px
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The formats are automatically detected based on the horizontal resolution. Using different
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formats as the ones listed may lead to unexpected results since the format check has been
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kept as simple as possible.
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