Sony SDX-800V/R User Manual

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SONY AIT-3Ex drive SDX-800V series Ver.1.1 

Operation Code (3Ch) 

Obsolete Reserved

Mode 

Buffer ID  

(MSB)  

 

 Buffer 

Offset  

  

(LSB) 

(MSB)  

 

 Allocation 

Length  

  

(LSB) 

Control 

READ BUFFER is used in conjunction with WRITE BUFFER as a diagnostic function for testing the data buffer and 
the SCSI bus integrity of the drive. A REWIND command should be sent to the drive after WRITE/READ BUFFER 

diagnostic testing to return to normal operation. 

Note: This command may not be used to recover data that is buffered within the drive. If the drive receives a READ 

BUFFER without having had a prior WRITE BUFFER command, only the four byte header will be returned. There is 

no available data to return, as the drive writes any buffered data to tape prior to accepting either a READ BUFFER or 

WRITE BUFFER for the first time. 

Mode: The drive supports the following values within this field. If any other value is set, the drive will terminate the 

command with a CHECK CONDITION status and an ILLEGAL REQUEST sense key set.  

Mode Description 
0000b 
0010b 
0011b 
1010b 
1011b 

Combined Header and Data 
Data 
Descriptor 
Echo Buffer 
Echo Buffer Descriptor 

Combined Header and Data Mode-in this mode, the drive returns a four-byte header followed by the data bytes. The 

drive terminates the DATA IN phase when Allocation Length bytes of header plus data have been transferred or 

when the header and all available data have been transferred to the initiator, whichever is less. The four-byte READ 
BUFFER header is followed by data bytes from the drive's data buffer. 

Reserved 

(MSB)  

 

 

Available Length  

 

  

(LSB) 

Available Length: specifies the total number of data bytes that are available in the target's data buffer. This number 
is not reduced to reflect the Allocation Length nor is it reduced to reflect the actual number of bytes written using the 

WRITE BUFFER command. Following the READ BUFFER header, the target will transfer data from its data buffer. 

Data Mode - in this mode, the DATA IN phase contains buffer data only.