Optical Drive and Library SCSI-2 Command Reference

SCSI-2 Drive Command Set
Read Long Command (3EH)
Chapter 2 2-105
SCSI-2 Drive Commands
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, & 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
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 2K media, 1200 bytes for 1K
media, or 610 bytes for 512 media.
A Sector Count bit of 0 indicates the transfer length is
represented in bytes.
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.
NOTE When this command is executed with 14X 512 or 1024 byte/sector media,
the drive will return a CHECK CONDITION status. The sense key/
additional sense code will be set to ILLEGAL REQUEST/INVALID
COMMAND.