Optical Drive and Library SCSI-2 Command Reference

SCSI-2 Drive Command Set
Write Long Command (DFH)
Chapter 22-148
Transfer
Length The Transfer Length field specifies the number of bytes
of data and ECC information to be read:
4096 media = 4760 bytes (4096 data + 664 pointer, CRC,
pad, & ECC). For 9.1 Gbyte Capacity drives only.
2048 media = 2380 bytes (2048 data + 332 pointer, CRC,
pad, and ECC). For 5.2 Gbyte capacity drives only.
1K media = 1200 bytes (1024 data + 176 pointer, CRC,
pad, &ECC).
512 media = 610 bytes (512 data + 98 pointer, CRC, pad,
&ECC).
All other numbers are rejected unless SC = 1.
Rel Adr A relative address bit of one indicates that logical block
address specified is a two’s complement offset from the
last logical block address accessed.
A value of 0 indicates that the logical block address is an
absolute address.
PBA A Physical Block Address bit of 1 indicates that physical
block addressing is used.
A PBA bit of 0 indicates that logical block addressing is
used.
SC A Sector Count bit of 1 indicates the transfer length is
represented in sectors rather than bytes. A "sector"
consists of 2380 bytes for 2048 media, 1200 bytes for
1024 media or 610 bytes for 512 media.
A Sector Count bit of 0 indicates the transfer length is
represented in bytes.
NOTE If this command is executed for write-once disks, the drive returns a
CHECK CONDITION status with the Sense Key/Additional Sense Code
set to Illegal Request/Invalid Command Operation Code.