From: http://www.printershowcase.com/color-laser-printers.aspx?gclid=CKWUyPyGqr8CFeXm7AodrV8Aiw

Shows comparison of major vendors printers

551 = Small business 451 = Personal

From: http://www.allbusiness.com/electronics/computer-equipment-computer-printers/8239720-1.html

First Rule of Thumb: Assume that everyone prints 35 pages per day.

551 = 75000 duty cycle 451 = 40000 duty cycle

User: root Password: last 6 of MAC

  The XPS file format was designed by Microsoft as a replacement for the 32-bit Enhanced Metafile 
  (EMF) picture format due to inconsistencies between different types of EMF formats. The XPS format
   may be viewed and opened with Microsoft's XPS viewer and selected programs on the Mac and Linux 
   platforms. Like Adobe's PDF, the XPS format enables documents and photos to be distributed via 
   the Internet without the risk of alteration or manipulation.

From: http://h10025.www1.hp.com/ewfrf/wc/document?docname=c01796821&cc=us&dlc=en&lc=en&os=4063&product=83027&sw_lang=

  Deskjet 6122 and 6127	= Deskjet 990c

How to Reset the Brother DR250 Drum?

http://ezinearticles.com/?How-to-Reset-the-Brother-DR250-Drum?&id=6769340

Resetting the DR250 drum without the starter sheet. In the event that the user does not have a starter sheet and is likewise unable to hand cut one, there is still one sequence left to reset the Brother DR250 drum. First, open the printer front cover and press the 'Option“ button while the front door is still open. Next, press the up arrow or the positive key to reset the drum automatically with no starter sheet required. All you have to do is to follow these instructions and a reset could be done seamlessly.