Specifications

Data Structures
1.16 SCSI Connection Descriptor Table (SCDT)
1.16 SCSI Connection Descriptor Table (SCDT)
The SCSI connection descriptor table (SCDT) contains information specific to a
connection established between a SCSI class driver and the port, such as phase
records, timeout values, and error counters. The SCSI port driver creates an
SCDT each time a SCSI class driver, by invoking the SPI$CONNECT macro,
connects to a device on the SCSI bus. The class driver stores the address of the
SCDT in the SCSI device’s UCB.
The SCSI port driver has exclusive access to the SCDT. A SCSI class driver has
no access to this structure.
The SCDT is illustrated in Figure 1–19 and described in Table 1–18.
Figure 1–19 SCSI Connection Descriptor Table (SCDT)
SCDT$L_FLINK* 0
SCDT$W_SIZE*SCDT$B_TYPE*SCDT$B_SUBTYP* 4
ReservedSCDT$B_FLCK* 8
SCDT$L_FPC* 12
SCDT$L_FR3* 16
SCDT$L_FR4* 20
SCDT$L_STS* 24
SCDT$W_SCDT_TYPE*SCDT$W_STATE* 28
SCDT$L_SPDT* 32
SCDT$L_SCSI_PORT_ID* 36
SCDT$L_SCSI_BUS_ID* 40
SCDT$L_SCSI_LUN* 44
SCDT$L_AUXSTRUC 48
SCDT$L_SCDTLST 52
SCDT$L_SCDRP_ADDR* 56
SCDT$L_BUS_PHASE* 60
SCDT$L_OLD_PHASES* 64
SCDT$W_PHASES* (44 bytes) 68
SCDT$L_PHASE_STK_PTR* 112
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