Atari 8-bit Colour



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This is the home of CpegView, the colour JPEG viewer for Atari 8-bit computers. CpegView is based on Juddpeg, the JPEG decoder and viewer for the C=64, written by Stephen L. Judd and Adrian Gonzalez.

CpegView 0.5 (18Aug07)

The colour JPEG viewer for Atari 8-bit computers

Greyscale JPEG viewers

The greyscale JPEG viewers

NOTE: The colour viewer needs 64K of RAM, this means using the RAM under the OS. Most versions of SpartaDOS also use this area and your machine WILL crash if you try to run the colour viewer with most versions of SpartaDOS on a 64K machine. If you have 128K or more, then CpegView has an option to use extended memory instead of the RAM under the OS, this will allow CpegView to run with SpartaDos.

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Have you found a bug? Do you have an idea for further improvements? If so, send me an e-mail.

This version works on most baseline JPEGs out there. It will not work on progressive JPEGs. Progressive JPEGs are designed for viewing over a slow connection. When viewing a progressive JPEG, it starts out as a low quality fuzzy image which becomes clearer as more data is downloaded. The way progressive JPEGs are implemented makes then harder (although not impossible) to handle in 48/64K of RAM.

Progressive JPEGs can be converted to baseline JPEGs using the jpegtran program provided by the IJG (The Independent JPEG Group):

jpegtran input.jpg > output.jpg

This may also fix problems with other images that can't be displayed. The jpegtran program is available for many systems, although not (unfortunately) for the Atari 8-bit, it can be downloaded from

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Screenshot Gallery

Want to see some screenshots? Take a look at the Gallery

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First boot up into your favourite DOS, without BASIC (hold down the OPTION key when booting XL/XE models, remove all cartridges on 400/800 models) then load CpegView (use the L option under DOS 2.0/2.5/MyDOS or equivalent).


Once loaded, CpegView will display all files with a .JPG extension on drive 1. To load a file, press the letter displayed next to the file name. To view the files on a different drive, or redisplay the files on the current drive, press the appropriate drive number (1 for D1:, 2 for D2:, etc.). Pressing the Tab key will allow you to change the files listed. Change the mask to *.* to view all files and subdirectories on the current drive. On a 128K or more machine, pressing the X key will swap between using the RAM under the OS or extended RAM to decode the image.

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Technical details

CpegView has 5 different display modes:

  • 80x200 in 256 colours: 16 colours x 16 levels of grey (APAC)
  • 160x200 in 64 colours: 16 colours x 4 levels of grey (CIN)
  • 320x200 in 32 colours: 16 colours x 2 levels of grey (C8)
  • 160x100 in 480 colours: 16 colours x 30 levels of grey (TIP)
  • 160x200 in 144 colours: 9 colours x 16 levels of grey (RIP)

  • Source code

    The source code comes in two parts, the decoder and the viewer. The decoder is a modified version of Stephen L. Judd's jpz1223-8 file.  The viewer has been written from scratch for the Atari.  New viewers can be written by replacing the viewer code with your own. No modification of the decoder is needed. Details of how to do this are in the decoder and the viewer source code.

    The source code is in ca65 format, part of the cc65 cross compiler package.

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    In the pipeline

    Here is the current development plan:

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    Any problems, suggestions, comments, bugs, feedback? Let me know

    Thanks to:
    Stephen L. Judd - for writing the original C=64 version and making the source available

    Also thanks to:
    René de Bie, Mathy van Nisselroy, TJ Edmister, Marco Antonio Checa Funcke, James Bradford, Chris Martin, Andreas Magenheimer, Piotr Fusik, Daniel Miller, Andrew Floyd - for comments, suggestions, ideas, feedback and other help.


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