
Parity Options
2-23
Status of SCSI
Parity Signal
SCSI Status Zero
(SSTAT0), Bit 0
This status bit represents the active high current state
of the SCSI SDP0 parity signal.
SCSI SDP1 Signal
SCSI Status Two
(SSTAT2), Bit 0
This bit represents the active high current state of the
SCSI SDP1 parity signal.
Latched SCSI Parity
SCSI Status Two
(SSTAT 2), Bit 3
SCSI Status One
(SSTAT1), Bit 3
These bits reect the SCSI odd parity signal
corresponding to the data latched into the SCSI input
Data Latch (SIDL) register
Master Parity Error
Enable
Chip Test Four
(CTEST4), Bit 3
Enables parity checking during master data phases.
Master Data Parity Error
DMA STatus
(DSTAT), Bit 6
Set when the SYM53C895 as a master detects that a
target device has signalled a parity error during a
data phase.
Master Data Parity Error
Interrupt Enable
DMA Interrupt
Enable (DIEN),
Bit 6
By clearing this bit, a Master Data Parity Error does
not cause IRQ/ to be asserted, but the status bit is set
in the DMA Status (DSTAT) register.
Enable Parity Error
Response
Command, Bit 6
Parity checking and parity error reporting are enabled
on the PCI bus.
Table 2.6
SCSI Parity Control
EPC1
1. Key:
EPC = Enable Parity Checking (bit 3 SCSI Control Zero (SCNTL0))
ASEP = Assert SCSI Even Parity (bit 2 SCSI Control One (SCNTL1))
AESP1
Description
0
Does not check for parity errors. Parity is generated when sending SCSI
data. Asserts odd parity when sending SCSI data.
0
1
Does not check for parity errors. Parity is generated when sending SCSI
data. Asserts even parity when sending SCSI data.
12
2. This table only applies when the Enable Parity Checking bit is set.(SCNTL0)
0
Checks for odd parity on SCSI data received. Parity is generated when
sending SCSI data. Asserts odd parity when sending SCSI data.
1
Checks for odd parity on SCSI data received. Parity is generated when
sending SCSI data. Asserts even parity when sending SCSI data.
Table 2.5
Bits Used for Parity Control and Generation (Cont.)
BIt Name
Location
Description