Reverse-engineering CD printing on the Epson R300

I have finally got a Windows box, a Linux box, Epson's CD printing software 
and a Stylus Photo R300 all in one room, and have taken a quick peek with 
hexedit.

This situation can persist indefinitely if needs be.

I've got 3 sample printouts - one with black text, one with coloured text and 
one with a picture background covering the whole CD. They are at:

http://www.whitepost.pwp.blueyonder.co.uk/printcd_picture_background
  (look out, this one's about 13MB)
http://www.whitepost.pwp.blueyonder.co.uk/printcd_text_black
http://www.whitepost.pwp.blueyonder.co.uk/printcd_text_multicolour

I can confirm Robert's observation - there is an SN instruction near the top 
of the file which appears significant. Changes to this instruction cause the 
printer to print absolutely nothing at all.

Understanding it that closely for CD printing may not be too important, 
however, as it doesn't seem to vary much between very different prints. 
Between 0x98 (start of SN instruction) and 0x145, all three files are 
identical.  I doubt the whole 173 bytes are related to the SN instruction, 
though I daresay anything's possible.

-- 
"Ronald McDonald? He's the newsreader, isn't he?"
  - Barbara Evans, demonstrating a typically Welsh grasp of current affairs


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