[Printers] HP Color Laserjet 2500 Results

[Michael Sleator]

It strikes me as interesting that the machines identified thus far
that use the "tosky" code are rather different beasts (if we lump
all of the HPs together).  The Toshiba FC-22 is a US$40k (with EFI
controller) production printer/copier with a four drum, laser-based
print engine.  The Kyocera C5016N is a US$2k small-office printer
with an LED-based single drum print engine, and the HP 2500 (US$1100)
& 2600N (US$400) are home/small-office printers with laser-based
single drum print engines.

It makes sense that different brand products might use the same
code if they use the same underlying print engine or controller,
but as near as I can tell, both Toshiba and Kyocera make their own
print engines for these machines, and the HPs use Canon engines.
The EFI controller for the FC-22 is a substantial system in its own
right, but I don't know at what level it operates.  That is, I don't
know if it actually generates the video signals that modulate the
(4) lasers.  The other machines have embedded controllers.

All of this suggests that either these machines use some common
low-level controller chip which imbeds the forensic codes, or
there's been some effort toward uniformity in the codes.  It would
be interesting to build a database of makes/models that use each
coding scheme.  This might yield some insight into the business
and politics behind it all.

Michael Sleator
sleat at sleator.com


>Patrick Burns writes:
>
>> Good to hear there will be more scans coming soon.
>> 
>> Is it just me, or do the Toshiba and Kyocera dot patterns sound a lot
>> like the HP patterns? I.e. 23x18 grid of dots (including blank
>> columns/rows).
>
>I think I'm going to try to start classifying printer models by the size
>of the grid they produce, if any, in the hope that the printers will
>then divide into "bins".
>
>I'm very curious about printers with subtle differences.  For example,
>as I believe someone has already mentioned here, some of the Epson
>Aculasers use the same 15x8 grid as the Xerox DocuColor, except that
>it's rotated to make it 8x15.  The Aculasers do encode serial number
>using the same scheme as the DocuColors, but they don't seem to encode
>date and time, and they use columns 2 and 3, which are unused on the
>DocuColor.  I don't know how we get a manufacturer code out of this; I
>doubt that it's represented in column 15 (as some people have suggested)
>because some DocuColors print a completely blank column 15.  It is
>possible that the orientation of the grid identifies a manufacturer, but
>this feels unlikely (because you could just print in landscape mode to
>alter the orientation, and in any case because it also looks like the
>Dell printers may be printing the same 8x15 grid).
>
>-- 
>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
>_______________________________________________
>printers mailing list
>printers at frotz.zork.net
>http://frotz.zork.net/cgi-bin/mailman/listinfo/printers