Method of determining the configuration of devices installed on a

Abstract

A method where at power-on and before loading an option ROM the DMA and interrupt controller register values are saved. After option ROM initialization current DMA and interrupt controller register values are compared to saved register values for determining DMA and interrupt controller usage by an expansion board. The usage information is saved in NVRAM until the operating system is booted and a configuration routine is executed. Additionally, each slot on the system bus is individually enabled and each address of an address range is read to determine whether an expansion board is installed in the slot and responding to a read. If the data value read is unequal to the undriven value of the data bus, then an expansion board is responding and information is logged into an I/O map. Otherwise, a second read is performed, and certain control lines are latched for determining whether an expansion board is driving those lines. If so, an expansion board is responding. Otherwise, the system then performs a further special read to determine the data bus response time. If the response time is faster than the response time of an undriven bus, an expansion board is responding. In this way, an address map is created for the system bus. This map is then used with the DMA and interrupt usage to determine the system configuration by comparing the map and usage to standard signatures of known boards. The system configuration is the passed to standard configuration software.