Appendix G

Future Standardization

This appendix is included to provide insight into some possible future 
extensions to SCSI that are being considered by X3T9.2.  Although X3T9.2 has 
addressed some of these extensions, many details remain to be resolved.  
Further work by X3T9.2 may result in changes or additions to these extensions.  
Please contact the Chairman of X3T9.2 for the current status of this activity.

  Six new commands are being considered, three for targets that support 
caching, one to provide a means to read the medium defect data, and two to 
provide a standardized method for writing and reading the target's data buffer 
(principally intended to support start-of-day tests that insure data path 
integrity).  The tentative operation codes are as follows:

==============================================================================
Operation
  Code      Type   Command Name             Device Types
------------------------------------------------------------------------------
   34H       O     PRE-FETCH                \  Direct Access, Write-Once
   35H       O     FLUSH CACHE               > Read-Multiple, and
   36H       O     LOCK/UNLOCK CACHE        /  Read-Only Direct Access
   37H       O     READ DEFECT DATA         Direct Access
   3BH       O     WRITE BUFFER             All
   3CH       O     READ BUFFER              All
------------------------------------------------------------------------------


  New parameters are being considered in several of the existing commands:

  (1) Cache control bits are being considered for bits 3 and 4 of byte 1 in 
several group 1 commands, including READ, WRITE, WRITE AND VERIFY, and VERIFY.

  (2) Byte 1 of the Defect List in the FORMAT UNIT command may be used to 
provide additional defect management control.

  (3) Bits 0 _ 3 of byte 3 of the Inquiry Data in the INQUIRY command may be 
used to identify that the device supports certain additions to the standard.  
One such addition that is being considered is optional fields within the 
Inquiry Data to identify the manufacturer and the product model information.

  (4) Extensions to the MODE SELECT and MODE SENSE commands are being 
considered to provide a standard means to control certain target parameters.  
Bits 0 _ 5 of byte 2 of the MODE SENSE command are being considered for use in 
controlling which target parameters are returned by this command.









