Specifications

System Macros Invoked by Drivers
SPI$SET_CONNECTION_CHAR
Table 2–12 (Cont.) SPI$SET_CONNECTION_CHAR Macro Settable
Characteristics
Longword Contents
8 Select retry count. Maximum number of retries allowed on
this connection while waiting for the port to be selected by
the target device.
9 Command retry count. Maximum number of retries allowed
on this connection to successfully send a command to the
target device.
10 Phase change timeout. Default timeout value (in seconds) for
a target to change the SCSI bus phase or complete a data
transfer. This value is also known as the DMA timeout.
Upon sending the last command byte, the port driver waits
this many seconds for the target to change the bus phase
lines and assert REQ (indicating a new phase). Or, if the
target enters the DATA IN or DATA OUT phase, the transfer
must be completed within this interval.
If this value is not specified, the default value is 4 seconds.
11 Disconnect timeout. Default timeout value (in seconds) for a
target to reselect the initiator to proceed with a disconnected
I/O transfer.
If this value is not specified, the default value is 4 seconds.
12 SCSI-2 device characteristic status bits. Bits of this longword
are defined as follows:
Bit Description
0 When set, (SCDT$V_SCSI_2) indicates the device
connection is SCSI-2 conformant.
1 When set, (SCDT$V_CMDQ) indicates the device
connection supports command queuing.
Inputs to the SPI$SET_CONNECTION_CHAR macro include the following:
Location Contents
R2 Address of the connection characteristics buffer.
R4 Address of the SPDT.
R5 Address of the SCDRP.
SCDRP$L_CDT Address of the SCDT.
The port driver returns the following values to the class driver, preserving R3,
R4, and R5:
2–92