UNDERSTANDING THE ESTIMATED LEVEL OF YOUR PRINTER INK:

Some HP printers have included in their software accessory called a deputy 'Toolbox (in English, Toolbox) "which includes a section called Estimated Ink Level. It is a great tool that allows the user to have instant feedback of the estimated amount of ink cartridges, which avoids the problem start printing a lot of work and not complete it due to lack of ink.

The only problem is that when you recycle these cartridges, and they are put back into the printer, reading the ink level will remain low or empty, and the software will display a message stating when the user tries to print a document.
Unfortunately, we all know the fact as strange by customers, which often are wary of the service.

BUT ... HP HOW DOES THAT?!?

The company built a serial number on the tape contacts located on the back of the cartridge. Thereafter, inspect the printer how much ink the same since the first reading of the serial number, and returns when the cartridge refilled to the printer, She remembers your serial number and gives the message of empty or low ink. This is located in the internal memory * firmware of the printer, not your software, and maintains information on the level of the last two ink cartridges.

Below are methods to reset the ink level for HP cartridges.

HP 800 Series - HP 15 / HP 23 / HP 41 / HP 45 / HP 78

HP 3000 Series - HP 21 / HP 22 / HP 27 / HP 28 / HP 56 / HP 57 / HP 58 (PHOTO)

* Firmware: software routines stored in read-only memory (ROM, EPROM, EEPROM).Unlike random access memory, a read-only memory remains intact even if no electrical current. The routines of departure and the directions of input / output low level is stored so it can not be modified, and no need to be loaded for execution. In addition to printers, many other products use firmware to operate as mobile phones, palmtops, audio and video players, etc..