DUO

Revision as of 18:14, 17 August 2020

DU* is a set of similar graphics formats for the Atari computers with unknown origin.

Identification

Files are exactly 113600 bytes long.

DUO    *.DU1 *.DUO (low resolution)
       *.DU2       (medium resolution)

Created by Anders Eriksson: http://ae.dhs.nu/
These are essentially 2 screens with over-scan interlaced together.

Low resolution files are 416x273 pixels:

16 words       palette
56784 bytes    screen 1
56784 bytes    screen 2
-----------
113600 bytes   total

Medium resolution files are 832x273 pixels:

4 words        palette
56784 bytes    screen 1
56784 bytes    screen 2
24 bytes       padding if present, otherwise total size is 113576 bytes
-----------
113600 bytes   total

Both screens use the same palette, but when viewed the human eye merges the two 
alternating images into one.

Software

• RECOIL

Sample files

• https://telparia.com/fileFormatSamples/image/duStar/

Links

• https://web.archive.org/web/20191221202304/http://www.atari-wiki.com/index.php/DUO_file_format