The full model number for the HP 21 black ink cartridge is C9351AE. This ink cartridge can be purchased through many electronics and printing stores and webpages.

I have only tried putting a Lexmark cartridge into a dell series 5 printer but it does not work. The electronics do not match and the printer rejected it.

You can purchase an HP C6657AE printer cartridge at your local Walmart or Target found in the electronics section. You can also purchase one online from Amazon and have it shipped directly to your house.

How does cartridge work? well lets say a cartridge game console for example, you have a circuit board with all the electronics then, the bit with the game on it is the missing bit, it is the separated bit of the circuit so u can have different information (eg game) so a cartridge is a piece of the circuit witch can have different information (before disc's came out they instead of them)

There are many places that a person can find laser toner cartridge for their Canon printer. The best places are Big Box stores that carry electronics such as Target or Best Buy.