C omputers differ quite a bit when it comes to data bus architecture.
Modern systems are capable of supporting a number of different protocols.
However, every peripheral component that is constructed for use with a particular type of data bus still needs to connect to that type of internal expansion slot or external expansion port on your computer. In other words, if you have a system that does not have PCI slots, you cannot plug in a PCI-specific device. Sometimes you can attach a component that uses a type of data bus your computer system normally doesn't support. This is accomplished through the use of a controller card , which acts as an interface for different data bus standards. For example, say you have a PCI-compatible printer that you want to use with your computer, which only supports the ISA data bus standard.