DATE:     July 27, 1992                     Document  X3T9.2/92-111r1


     TO:       X3T9.2 Committee (SCSI)


     FROM:     Peter Dougherty
              UNISYS CORPORATION


     SUBJECT:  Additional ASC / ASCQ  Codes For Data Compression

     =====================================================================




     There are a number of error conditions encountered when implementing
     data compression on SCSI devices which cannot be uniquely identified
     using currently defined ASC/ASCQ codes.  Unisys proposes that the
     following ASC/ASCQ combinations be added to SCSI-3.


     BYTE
     12   13

     ASC  ASCQ      DTLPWRSMOC  DESCRIPTION
     ___  ____      __________  __________________________________________

     0C   04        DT  W   O   COMPRESSION CHECK MISCOMPARE ERROR

     0C   05        DT  W   O   DATA EXPANSION OCCURRED DURING COMPRESSION

     0C   06        DT  W   O   BLOCK NOT COMPRESSABLE

     11   0D        DT  WR  O   DE-COMPRESSION CRC ERROR