Operating instructions

14-2
SCSI REFERENCE 1012975
CHAPTER 14—READ BUFFER (3Ch)
14.2 WHAT YOU SEND TO THE AUTOLOADER
Mode – Byte 01, Bits 2 through 0
The Mode field determines the type of operation to be performed. The
autoloader supports the following operations:
001b – Vendor Unique operation
010b – Data
Buffer ID – Byte 02
This field determines the type of buffer data to be transferred, as follows:
00h through 07h – Selects the section of the microcode to be copied to the
initiator. The Mode field must be set to 001b (Vendor Unique). See
Section 14.2.1 for more information about using the READ BUFFER
command to copy the autoloader’s microcode to the initiator.
80h – Specifies that the autoloader’s diagnostic data is to be copied to the
initiator. The Mode field must be set to 010b (Data). See Section 14.2.2 for
more information about using the READ BUFFER command to copy the
autoloader’s diagnostic data to the initiator.
Buffer Offset – Bytes 03 through 05
This field specifies the offset into the autoloader memory buffer specified by
the Mode field (byte 1, bits 2 through 0), as follows:
 When the Buffer ID is set to a value of 00h through 07h, the valid value for
this field is from 000000h through 020000h (0 to 131,072 bytes), minus the
Parameter List Length value. If the sum of the Buffer Offset and the
Parameter List Length exceeds 020000h, the autoloader returns CHECK
CONDITION status.
 When the Buffer ID is set to 80h, the value for this field must be 000000h.
Allocation Length – Bytes 06 through 08
This field specifies the number of bytes to be transferred by the current READ
BUFFER command. If the number of bytes specified is larger than the buffer
size, only the number of bytes in the buffer will be returned.
 When the Buffer ID is set to a value of 00h through 07h, the Allocation
Length determines how many bytes of data the autoloader returns for the
current READ BUFFER command (up to 131,072 bytes). By using the Buffer
Offset and Allocation Length, you can determine how many READ BUFFER
commands are required to return the full EEPROM image. If the sum of the
Buffer Offset and the Parameter List Length exceeds 020000h, the autoloader
returns CHECK CONDITION status.
 When the Buffer ID is set to 80h, the autoloader returns up to 00FFE0h
(65504 bytes) of diagnostic data or the number of bytes specified by the
allocation length, whichever is smaller.