Bit 7 6 5 4 3 2 1 0Byte0 - n (data defined by previous Data Mode WRITE BUFFER command)Echo ModeIn this mode, the library returns the same number of bytes of data as received in the prior Echo ModeWRITE BUFFER command from the same host. If a prior Echo Mode WRITE BUFFER command did notcomplete successfully the Echo Mode READ BUFFER command shall return Check Condition status. Thesense key shall be set to ILLEGAL REQUEST and the sense data shall be set to COMMAND SEQUENCEERROR. If the data in the Echo Buffer has been overwritten by another host the library shall return CheckCondition status. The sense key shall be set to ILLEGAL REQUEST and the sense data shall be set toECHO BUFFER OVERWRITTEN. The maximum length of the Echo Mode buffer is 256 bytes.Bit 7 6 5 4 3 2 1 0Byte0 - n (data defined by previous Echo Mode WRITE BUFFER command)Echo Buffer Descriptor ModeIn this mode, the media changer returns the descriptor information for the Echo Buffer. The Buffer Offsetfield is reserved in this mode. The Buffer ID field is ignored in this mode. Next table specifies the BufferDescriptor which is returned on a READ BUFFER command in Echo Buffer Descriptor Mode.Bit 7 6 5 4 3 2 1 0Byte0 Reserved EBOS1 Reserved2 Reserved (MSB)3 Buffer Capacity (LSB)Field descriptions:EBOS:The Echo Buffer Overwritten Support bit is set. The library shall returnECHO_BUFFER_OVERWRITEN sense data when the buffer is overwritten by another initiator.Buffer Capacity:The Buffer Capacity field returns the maximum size of the Echo Buffer in bytes. The Echo Buffercan store up to 256 bytes.3-52 TL2000 and TL4000 SCSI Reference
