1. A local system bus for a micro-processor based computer system including a plurality of controllers connected between the local system bus and at least one micro-processor, a system memory or an I/O bus, one of the controllers being a bus master and another being a bus slave during a bus transaction, the local system bus comprising: lines for carrying an address driven by the bus master and received by the bus slave; lines for carrying data driven by the bus master and received by the bus slave during a write transaction or driven by the bus slave and received by the bus master during a read transaction; lines for carrying signals generated by the bus master and received by the bus slave, for defining a transaction in progress; lines for carrying control signals for micro-processor operations; lines for carrying status signals asserted by the bus slave for indicating a status of the bus slave further comprising lines for carrying interrupt signals; and lines for carrying arbitration signals, wherein the lines for carrying arbitration signals comprise a line for carrying a bus hold request for permitting another controller to gain control of the local system bus.