Emerson MVME147 manual Enabling TARGET Role

Enabling TARGET Role

enable (word $0E = $C000), and with the following data structures reserved for TARGET role service.

a.Command Table (384 bytes)

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Note

During the TARGET role, when the TARGET enable packet is issued to the firmware, neither the custom command packet nor the command table shall be deallocated because firmware uses both areas for subsequent TARGET service.

b.Message-out area (the SCSI standard allows for a 258-byte extended message)

Note

In SCSI terms, all transfer directions are referenced to the initiator. For example, the data out phase is a data phase for data OUT of the initiator and INTO the TARGET. Therefore, the message-out area mentioned above is for message STORAGE from the initiator to the TARGET.

c.Take over the return vector specified in the packet of 1. above. Put the service routine address in the vector.

d.Load address register A2 with the address of the custom sequence packet described in 1. above.

e.Enter the SCSI firmware through the FUNNEL entry point ($FFFE078E) at interrupt level 2. (For a description of the FUNNEL module, refer to the SCSI Firmware Entry Points section in Chapter 1.

f.Examine the returned final status for a code of $xx17. This is a signal that the firmware has acknowledged the enable packet and the initiator command has been received. (This status may be preceded by a $A002 if the bus is occupied at the time that the enable packet was sent to the firmware.)

g.The service of the TARGET LUN is now interrupt-driven by the initiator. A selection interrupt causes the firmware to examine enabled TARGET LUNs and load commands and/or messages into the designated areas for service. If a command is received for an enabled TARGET logical unit, then the firmware returns to you with either a $xx17 final status (SCSI mode) or an intermediate status of $xx06 (SASI mode or initiator not supporting disconnection), indicating that the CDB has been loaded into

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