Explain any two techniques of bus.
The process of determining which bus master will have access to the bus is called Bus Arbitration.
An I/O module needs to gain control of the bus before it can raise the interrupt request line.The line can only be raised by one module at a time.The processor responds to the interrupt on the acknowledge interrupt line.The data lines are placed on by the requesting module.
Techniques can be used to identify the requesting I/O module.When more than one device is requesting interrupt service, they have a way of assigning priorities.The processor picks the interrupt line with the highest priority.The priority of modules is determined by the order in which they are polled.The priority of modules on a daisy chain is determined by the order in which they are placed.Bus arbitration can use a priority scheme.
The daisy chain scheme is shown in Figure 2.It was named after the structure for the grant line, which chains through each device from the highest priority to the lowest priority.If the lower priority device doesn't want the grant line, priority is built into the scheme.