Game cartridges were the first type of external media to be used with home video game consoles and due to continued improvements in capacity remained the most common until the mid nineties. Cartridges consisted of a printed circuit board carrying the ROM chips that stored the software. This circuit board was housed inside a plastic casing with a connector that enabled the device to interface with the console. In some cases, additional components were present that boosted the original console's power, such as a coprocessor or extra RAM.
By the early 21st century, the relatively high manufacturing costs of cartridges meant that they became replaced by optical media for home consoles; however, they are still in use in some hand held video game consoles.