You get this warning with the help of toner chips.What is a toner cartridge?Printer toner cartridges are designed with specific page yields.Nowadays laser printers or copiers usually use a toner chip (also called a smart chip) to monitor and count the pages used during printing.It is usually gold with a small PCB board and is dedicated to the storage unit for data storage, sometimes configured with the processor to respond to the request of the processor or copier.If a particular page is swallowed, it will contact your computer to alert you.What is a toner cartridge’s function?Save toner cartridge details (compatible toner model identification)Calculate and record print pages, toner powder volume and print coverage rate (printer calculates it based on pixels).This information is collected by the printer, fed to the toner chip and then stored by the toner chip storage unit.Some printer manufacturers design different chip codes for different regions which mean the toner chip is not compatible with different toner cartridges and printers.