If target mode is not enabled, the host adapter will behave on the SCSI interface as ifit were an ordinary SCSI initiator. Any attempt to select the host adapter will resultin a SCSI selection time out. Most reset operations, including Soft Reset, Hard Reset,and Power-On Reset will return the AHA-1740A/1742A/1744 Target Mode to the dis-abled state. SCSI resets, generated either by the host or by other SCSI devices, willnot change the previously established enabled or disabled state of Target Mode.Return Setup Data (Operation Code 0D)This command returns information describing the setup of the host adapter. The in-formation returned reflects either the values supplied by previous host adapter com-mands or default values. The command is followed by an outbound data transfer andan inbound data transfer. The outbound transfer is a 1-byte parameter indicating thelength of the required inbound data transfer. The inbound data transfer containsfrom zero to 255 bytes of information describing the setup of the host adapter. The in-bound information normally transferred will be truncated or padded with zeros asnecessary to transfer the requested number of bytes. The number of bytes normallytransferred by the AHA-1740A/1742A/1744 is 17.Byte Description MeaningOutbound Data Byte00 Data In LengthThe number of data bytesrequested can be from 0 to 255.A value of zero will be acceptedand 256 bytes will be returned.Bit 0 If this bit is zero, synchronousdata transfer negotiation willnot be initiated by the hostadapter, but will be respondedto if requested by an attachedSCSI device. If the bit is one,synchronous data transfernegotiation will be initiated bythe host adapter under thoseconditions which require suchnegotiation. The state is setfrom jumper J1.Bit 1 If this bit is zero, paritychecking on inbound SCSItransfers has beendisabled. If this bit is one,parity checking on inboundSCSI transfers is enabled. Thestate is set from jumper J1.Bit 2-7 Reserved (0)Inbound Data Summary00 SDT and Parity Status01 Transfer Speed This byte returns the valuepassed in to the host adapter bythe Set Transfer Speedcommand (see Set TransferSpeed in this chapter)02 Bus On Time Indicates the Bus On Time inmicroseconds (see Set Bus OnTime in this chapter))adaptec AHA-1740A/1742A/17445-10
