Operating instructions

SEPTEMBER 2005 MAGNUM 1X7 LTO AUTOLOADER
25-3
WHAT YOU SEND TO THE AUTOLOADER
25.2 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 performs the following operations:
100b – Write microcode to buffer but do not save it to EEPROM
101b – Write microcode to buffer and save entire buffer to EEPROM
Buffer ID – Byte 02
This field specifies which section of EEPROM is the target for the data in the
current WRITE BUFFER command. EEPROM is divided into eight sections, of
which six are used for functional code. Valid values for this field are 02h
through 07h. See Section 25.2.1 for more detailed information about the
sections of the code defined by each Buffer ID value.
Buffer Offset – Bytes 03 through 05
This field specifies where in the buffer to begin writing the downloaded
microcode data. Valid values for this field are from 000000h to 020000h minus
the Parameter List Length value. If the sum of the Buffer Offset and the
Parameter List Length is greater than 020000h (131,072) bytes, the autoloader
returns CHECK CONDITION status.
Parameter List Length – Bytes 06 through 08
The Parameter List Length field specifies the number of bytes to be transferred
by the current WRITE BUFFER command. Valid values for this field are from
000000h to 020000h (131,072) bytes. If the sum of the Buffer Offset and the
Parameter List Length is greater than 020000h (131,072) bytes, the autoloader
returns CHECK CONDITION status.
25.2.1 USING WRITE BUFFER TO UPDATE THE AUTOLOADER
M
ICROCODE
Although the autoloader’s EEPROM has a capacity of 1,048,576 bytes
(100000h), the autoloader buffer can only accept 131,072 bytes (20000h) of data
at one time. Therefore, in order to program the entire EEPROM, the microcode
must be downloaded and stored in the EEPROM in sections. Each section of
the EEPROM contains 20000h bytes, as follows:
 The first 262,144 bytes (bytes 000000h through 03FFFFh) of the microcode
update file correspond to the Boot Block code, which cannot be changed.
These bytes should not be transferred to the autoloader. The Boot Block code
is a subset of the autoloader microcode that allows the functional code to be
updated even if the functional code currently stored in the autoloader has
been so damaged as to make it inoperable.
Note: If you attempt to transfer data to the section of memory that is
reserved for the Boot Block code the autoloader returns Check
Condition status with an ASC/ASCQ of 24h/00h (Illegal Request).