A ROM cartridge, usually referred to in context simply as a cartridge, cart, cassette, or card, is a replaceable part designed to be connected to a consumer electronics device such as a home computer, video game console or, to a lesser extent, electronic musical instruments.
In most cases the designs were fairly crude, with the entire address and data buses exposed by the port and attached via an edge connector; the cartridge was memory mapped directly into the system's address space[4] such that the CPU could execute the program in place without having to first copy it into expensive RAM.
Computers using cartridges in addition to magnetic media are the VIC-20 and Commodore 64, MSX, Atari 8-bit computers,[5] TI-99/4A (where they were called Solid State Command Modules and were not directly mapped to the system bus) and IBM PCjr[6] (where the cartridge was mapped into BIOS space).
[9] As compact disc technology came to be widely used for data storage, most hardware companies moved from cartridges to CD-based game systems.
[14] Micro Machines 2 on the Genesis/Mega Drive used a custom "J-Cart" cartridge design by Codemasters which incorporated two additional gamepad ports.
[15] Storing software on ROM cartridges has a number of advantages over other methods of storage like floppy disks and optical media.
As the ROM cartridge is memory mapped into the system's normal address space, software stored in the ROM can be read like normal memory and since the system does not have to transfer data from slower media, it allows for nearly instant load time and code execution.
ROM cartridges can be damaged, but they are generally more robust and resistant to damage than optical media; accumulation of dirt and dust on the cartridge contacts can cause problems, but cleaning the contacts with an isopropyl alcohol solution typically resolves the problems without risk of corrosion.
Techniques such as bank switching were employed to be able to use cartridges with a capacity higher than the amount of memory directly addressable by the processor.
As video games became more complex (and the size of their code grew), software manufacturers began sacrificing the quick load times of ROM cartridges in favor of greater storage capacity and the lower cost of optical media.