[Printers] MAKE reader suggests Xerox col 15 is parity

[Seth David Schoen]

MAKE has coverage of the Xerox codes:

http://www.makezine.com/blog/archive/2006/05/the_davinci_code_try_the_da_xe.html

In the comments, Phillip Torrone says that a reader suggested that column
15 is a parity column (perhaps instead of column 1).  In that case column
1 could conceivably be a data column (maybe seconds, so that columns 5,
2, and 1 give hour, minute and second?).  Does anyone have an opinion on
this?

A counterargument is that some printers appear to regularly print a
completely empty column 15.  We originally thought it was unused because
the first Xerox printers we looked at never put anything in that column
(except for the single parity bit in the upper right-hand corner).
Therefore, there must be some printers that don't use column 15 for
parity.  Since the rows do have odd parity, and row 1 is the only
remaining row with values that change from print to print and that we
don't know how to interpret in any other way, it seems that the MAKE
reader's interpetation is wrong.

-- 
Seth Schoen
Staff Technologist                                schoen at eff.org
Electronic Frontier Foundation                    http://www.eff.org/
454 Shotwell Street, San Francisco, CA  94110     1 415 436 9333 x107