Emerson MVME147 manual TARGET Sequence Custom Packet WORDS $04 and $06

TARGET Sequence Custom Packet

WORDS $04 and $06:

SCRIPT POINTER -- The address of the TARGET script to be performed to service the initiator request.

In TARGET role, the MVME147 controls the SCSI bus. The TARGET script tells the firmware which information transfer phases to cycle through to service the initiator request that was encoded in the CDB.

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Note

In TARGET role, the names of the information transfer phases are consistent with initiator role. By SCSI definition, transfer direction is always referenced to the initiator. That is, the message in phase is a message transfer INTO the initiator. For TARGET role the message-in phase is still INTO the initiator (notice it is OUT of the TARGET).

TARGET scripts to service commands do not include command phases. Below are examples of TARGET scripts for two CDBs; one is a receive CDB and the other is a send CDB. Example 1: Receive (peripheral device type = processor

devices)
CDB byte 0: $08	Command is a receive
CDB byte 1: $20	The desired LUN is 1
CDB byte 2: $00	Allocation length MSB
CDB byte 3: $04	Allocation length
CDB byte 4: $00	Allocation length LSB
CDB byte 5: $00	Control byte=0: no link, no flag

Target script for example 1:

DC.B $0C DATA-IN PHASE

DC.B $10 STATUS PHASE

DC.B $18 MESSAGE-IN PHASE

DC.B $1C END OF TARGET SCRIPT

The command table contains the information required to carry out the bus phase. For example, the data pointer tells the firmware where the buffers are located in MVME147- accessible memory.

1.During the data-in phase, the $400 bytes are sent to the initiator.

2.During the status phase, the GOOD status is sent to the initiator.

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