The capacity of a bus is how much data it can carry in a second. This is called double pumping the bus. An internal bus is a bus inside the processor, moving data, addresses, instructions, and other information between registers and other internal components or units. A bus master is a combination of circuits, control microchips, and internal software that control the movement of information over a bus. A processor bus is a bus inside the processor.
Some processor designs simplify the internal structure by having one or two processor buses.
In a single processor bus system, all information is carried around inside the processor on one processor bus. In a dual processor bus system, there is a source bus dedicated to moving source data and a destination bus dedicated to moving results. An alternative approach is to have a lot of small buses that connect various units inside the processor. A system bus connects the main processor with its primary support components, in particular connecting the processor to its memory. Depending on the computer, a system bus may also have other major components connected.