
PRELIMINARY
35
A
82454KX/GX (PB)
2.4.4
PCISTS—PCI STATUS REGISTER
Address Offset:
06–07h
Default:
0240h
Attribute:
Read Only and Read/Write Clear
The PCISTS Register reports the occurrence of a PCI master abort/PCI target abort, system error, and parity
errors. This register also indicates the DEVSEL# timing that has been set by the PB hardware. Software sets
the bits labeled R/WC to 0 by writing a 1 to them.
2
Bus Master Enable—RO. The PB does not support disabling its bus master capability. This bit is
hardwired to 1.
1
Memory Space Enable. 1=Enable PCI memory accesses to the host bus. 0=Disable.
0
I/O Space Enable. 1=Enable PCI I/O accesses to the host bus. 0=Disable.
Bits
Description
15
Parity Error Detected—R/WC. 1=PB detected a PCI address or data parity error. The PB checks all
address cycles, regardless of the intended target, for address parity errors. When the PB is involved
in a PCI transaction (as either master or target), it checks all data cycles for data parity errors. The
Parity Error Detected bit is set independent of whether parity error reporting (bit 6 in the PCICMD
Register) is enabled.
14
Signaled System Error—R/WC. 1=PB asserted the SERR# signal.
13
Received Master Abort—R/WC. 1=PB is PCI bus master and terminates its transaction (other than
Special Cycle commands) with a master-abort.
12
Received Target Abort—R/WC. 1=PB as a PCI bus master received a target abort.
11
Signaled Target Abort—R/WC. 1=PB issued a target abort. This only happens for invalid byte
enables during an I/O access or a Hard Failure from a host bus agent.
10:9
DEVSEL# Assertion—RO. Bits[10:9]=01 (indicates medium timing when the PB responds as a
target).
8
Data Parity Error Reported—R/WC. This bit is set to 1 when all of the following conditions are met:
1.) The PB asserted PERR# or sampled PERR# asserted. 2.) The PB was the bus master for the
transaction in which the error occurred. 3.) The Parity Error Response bit is set to 1 in the PCICMD
Register.
7
Fast Back-to-Back Capable—RO. This bit is hardwired to 0 to indicate that the PB is not capable of
accepting fast back-to-back transactions that are not to the same agent.
6:0
Reserved.
Bits
Description