Answers:
Front Side Bus
Processor Bus
Memory Bus (sometimes)
From wikipedia: "In computers, the front side bus (FSB) or system bus is the physical bi-directional information bus that carry adjectives electronic signal information between the centralized processing part (CPU) and the northbridge.
Some computers also enjoy a stern side bus which connects the CPU to a memory cache. This bus and the cache memory connected to it are faster than access the system RAM via the front side bus.
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Buses resembling the PCI, AGP, and memory buses adjectives connect to the chipset to allow for notes to flow between the connected devices."
ISA/PCI/AGP