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What is a toner cartridge chip?

What exactly is a toner cartridge chip? What does a toner cartridge chip actually do? What can a chip NOT do?

Before we get started, let's cover a little chip history.

Before chips there were a decent amount of cartridges that used electrical fuses of one shape or another. They were cheap and easily replaced.

When cartridge chips first appeared, they were very simple and easily resettable. In fact they could be reset with a simple box that would re-write the code. First seen in the spring of 1992 the TEC 1305 printer was one of the first to use chips. The chips used in the TEC 1305 and also the Xerox N24 printer which came out soon after were fairly simple devices.

HP at first also used very simple off the shelf chips for the Colour LJ 4500. They just plug into a socket.

Lexmark has been one of the most challenging OEM's for our industry. The Optra T (4069) wasn't too bad to overcome, but with the release of the T520 series, our world changed. One of the first aftermarket solutions was to have a wired large board that actually used the used OEM chip in a "Piggyback" style. It was wired to a small pass-through board that fit into the OEM slot. Then came the first stand alone boards. They started out with somewhat large components that over time were miniaturized as our industry evolved. Then finally the new smaller boards with extremely complex encryption codes which is what we have now.

With few exceptions all the HP and Lexmark chips have been the contact types which have plated pads on the boards that touch contacts in the machines when installed. (HP- 4100, 4600 and 9000 excluded).

Another chip style is the RF (Radio Frequency) type. These chips broadcast a small signal through an antenna to communicate to the printer. The antenna can be a hard wire coil or even a thin label with a flexible circuit printed on it. They can and do look very different from one manufacturer to another. The latest development for both the OEM and aftermarket is in dedicated Microprocessor chips. They are designed specifically for one purpose. The programming is actually built in and is more hardware than software.


Now that we've covered a short history, we still have the questions: What exactly is a cartridge chip? What does a chip actually do?

Let's start with what they are;

A cartridge chip is a device that communicates with a machine through either direct contact or RF (Radio Frequency).

  • They typically are mounted on a small circuit board.
  • They have memory to store information
  • Sometimes have a processor to provide the correct responses
  • Have a power control circuit to feed the processor when needed.
  • Provide power protection from voltage spikes etc.
The chip usually:
  • Contains cartridge specific information (So the machine knows the correct cartridge has been installed)
  • Lists the cartridge yield
  • Lists the Region (Worldwide, some printer manufacturers use a different chip code for different geographical regions)
  • Provides authentication to allow communication
  • Must answer machine challenges correctly
  • Use the correct encryption
  • Answer within a specific time frame
  • Holds data as needed to allow the machine to manage the toner use
  • The machine determines the toner level and writes this information to the chip
  • The chip will send this information back to the machine as requested.
  • Stores on going machine information as the cartridge is used
  • The machine counts the pages printed and stores this info on the chip
  • The machine counts the pixels printed (Page coverage) and also store this on the chip
  • The chip will send this information back to the machine as requested

It should be noted here that early versions of machines did not have very accurate page coverage calculating systems. They have improved immensely, but still are not perfect.

So now we know what a chip is. Now we come to the next question:


The chip will store and when requested by the machine, send the machine info on the cartridge part #, Yield, and region. As the cartridge is used, the printer will send the chip information on the pages printed, page coverage and estimated toner remaining. This information is stored on the chip and will be sent back to the printer as requested. The machine is the master. It first sends the data to the chip and then reads the chip data back as needed on all the above items.

The chip is the slave. The chip must be capable of correctly responding to the machine in a certain time frame using the correct encryption;

  • The correct cartridge info (Part #)
  • Correct region
  • Cartridge new or used
  • If used the page count and page coverage
  • Toner remaining in the cartridge.
  • The chip information MUST match the yield for the toner load.
  • Chips are not able to compensate for large changes
  • Mismatched info will result in errors.


A chip does NOT control the yield. They are preprogrammed with the start yield, but the machine determines the page count, page coverage, toner low and toner out. The machine does write this info to the chip so when requested the chip will report it back, but the initial determination comes from the printer. Once toner low or out is written to the chip, it's irreversible.
This is why if you have a bad electrical contact to a mag roller and get a toner low error; even after you fix the contact issue the cartridge chip will still report a toner low condition.

Once these errors have been written to the chip, the only way to clear it is to replace the chip.

Chips do not shut a machine down at a certain page count
Chips do not have this ability. Machines will use the information stored on the chip to determine if or when it should stop printing, but that information initially came from the machine. It was not calculated by the chip.

Chips also do not control toner level information.  This is also something that chips do not have the ability to do.

The machine determines the toner level by counting the number of pixels. The machine uses a formula to calculate the amount of toner used per pixel and stores that data on the chip. Some machines also have mechanical, electrical or optical methods of determining the toner level. Again, this info is stored on the chip, but is not determined by the chip.

For a chip to determine the toner level, pages printed etc it would need to be incredibly complex and would take up much more space than would be economically feasible. Why duplicate expensive circuitry over and over when you can do it once in the machine itself?

Chips cannot give an error message.
The machine contains all the circuitry needed to generate error codes. If the machine cannot see or read a chip that will generate an error code, but it always comes from the machine, not the chip.

Like it or not, cartridge chips are now an integral part of our industry. We don't see them going away anytime soon. In fact, following recent trends they are probably going to get more complicated. Cartridge chips continue to get smaller so it's our opinion that while they may become more complex in their code, the functions they can perform will stay basically the same.