Method and apparatus for processing a target retry from a PCI target device to an ISA master devise using a PCI/ISA bridge

摘要

When an ISA bus master on an external ISA bus tries to access a device on a PCI bus, a desk station-PCI/ISA (DS-PSI/ISA) bridge device converts a bus cycle on the ISA bus to a PCI bus cycle and commences a transaction for accessing a PCI device. At this time, if the target address-specified by the transaction cannot respond to the transaction and a target retry is generated by the target, the DS-PCI/ISA bridge device activates an I/O channel ready signal (IOCHRDY) on the external ISA bus. The ISA bus master is in a wait state. The DS-PCI/ISA bridge automatically retries the transaction after a predetermined time has elapsed.