Adaptec 1737100 Programmer Manual - Page 77

Register Descriptions PCI Registers PCI Configuration Header Registers At the deassertion edge of the PCI reset, the AIC-6915 starts reading the serial EPROM. At the same time, the BR_A1 input is sampled. If the board has a pull-up on this pin, the AIC-6915 replaces the default value of the following PCI configuration header registers: Vendor ID, Device ID, SubClass, Base Class, SubSystem Vendor ID, SubSystem Device ID, MinGnt (MinimumGrant), MaxLat (MaximumLatency) and Interrupt Pin, with the value read from the serial EEPROM. The CCIS (Configuration Card Information Structure) and MAC address are always read and stored in the appropriate registers. There are no default values for these registers. PCI VendorID Register Type: R Internal Registers Subgroup: PCI Configuration Header Byte Address: 00h - 01h Bit(s) 15:0 Table 7-3. PCI Vendor ID Register Reset rw Value Description/Function r 9004h VendorID[15:0]: The PCI Vendor Identifier register contains product information used by the HOST. The Adaptec Vendor ID default value is 9004h. This value can be changed to a value read from an external serial EEPROM if BR_A1' pin is '1' when PCIRST_ is deasserted. PCI DeviceID Register Type: R Internal Registers Subgroup: PCI Configuration Header Byte Address: 02h-03h Table 7-4. PCI Device ID Register Bit(s) rw Reset Value Description/Function 15:0 r 6915h DeviceID[15:0]: The PCI Device Identifier registers contain product information for use by the HOST during system initialization and configuration. The two Device ID bytes contain an Adaptec product code. The default product code for the AIC-6915 is 6915h. This value can be changed to a value read from an external serial EEPROM if BR_A1' pin is '1' when PCI_PCIRST_ is deasserted. 7-5