Rainbow Electronics DS31256 - Manual (Page 137)

DS31256
137 of 181
10.2 PCI Configuration Register Description
Register Name: PVID0
Register Description: PCI Vendor ID/Device ID Register 0
Register Address:
0x000
LSB
Vendor ID (Read Only/Set to EAh)
Vendor ID (Read Only/Set to 13h)
Device ID (Read Only/Set to 34h)
MSB
Device ID (Read Only/Set to 31h)
Bits 0 to 15/Vendor ID. These read-only bits identify Dallas Semiconductor as the device’s manufacturer. The
vendor ID was assigned by the PCI Special Interest Group and is fixed at 13EAh.
Bits 16 to 31/Device ID. These read-only bits identify the DS31256 as the device being used. The device ID was
assigned by Dallas Semiconductor and is fixed at 31256h.
Register Name: PCMD0
Register Description: PCI Command/Status Register 0
Register Address:
0x004
LSB
STEPC PARC VGA MWEN SCC MASC MSC IOC
Reserved (Read Only/Set to All Zeros) FBBEN PSEC
FBBCT UDF 66MHz Reserved (Read Only/Set to All Zeros)
MSB
PPE PSE MABT TABTM TABT DTS1 DTS0 PARR
Note: Read-only bits in the PCMD0 register are underlined; all other bits are read-write.
The lower word (bits 0 to 15) of the PCMD0 register is the command portion and is used for PCI bus control.
When all bits in the lower word are set to 0, the device is logically disconnected from the bus for all accesses,
except for accesses to the configuration registers. The upper word (bits 16 to 31) is the status portion and is used
for status information. Reads to the status portion behave normally but writes are unique in that bits can be reset
(i.e., forced to 0) but not set (i.e., forced to 1). A bit in the status portion resets when 1 is written to that bit
position. Bit positions that have 0 written to them do not reset.