The set of wires that carry memory addresses and data to and fro between a memory controller (Northbridge in a PC) and main memory (e.g. RAM) is called Memory Bus. It generally comprises of an Address Bus and a Data Bus and is often called a system bus. These are a part of the PC’s hierarchy of high speed communications channel used within the computer for transferring information between components. Provided the CPU is fast enough, it is the width of these buses that can be a hindrance in maximizing the performance of the system.