Command Specifications

4.4.4 READ BUFFER (3C)

 

Bit

7

6

5

4

3

2

 

1

0

Byte

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

0

 

 

 

 

X'3C'

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

1

 

0

0

0

0

 

Mode

 

 

 

 

 

 

 

 

 

 

 

 

 

2

 

 

 

X'00' (Buffer ID)

 

 

 

 

 

 

 

 

 

 

 

 

 

3

 

 

 

Buffer Offset (MSB)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

4

 

 

 

Buffer Offset

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

5

 

 

 

Buffer Offset

(LSB)

 

 

 

 

 

 

 

 

 

 

 

 

6

 

 

 

Transfer Byte Length (MSB)

 

 

 

 

 

 

 

 

 

 

 

7

 

 

 

Transfer Byte Length

 

 

 

 

 

 

 

 

 

 

 

 

8

 

 

 

Transfer Byte Length (LSB)

 

 

 

 

 

 

 

 

 

 

 

 

 

9

 

0

0

0

0

0

0

 

0

0

 

 

 

 

 

 

 

 

 

 

 

This command is used in combination with the WRITE BUFFER command to diagnose the normalcy of the HDD's data buffer memory and the SAS interface.

In this command, each data byte position in the data buffer must be specified in 4-byte units using buffer addresses.

The functions of this command and the contents of the data transferred to the INIT are specified by the "Mode" field in the CDB and one of the transfer modes shown in Table 4.62 can be selected.

Table 4.62 READ BUFFER transfer mode

"Mode" Bit

3

2

1

0

Transfer Mode

 

 

 

 

 

 

 

0

0

0

0

Header + Data, without Address Specification

 

0

0

0

1

Header + Data, with Address Specification

 

0

0

1

0

Data Only, with Address Specification

 

0

0

1

1

Buffer Descriptor

 

1

0

1

0

Echo buffer

 

1

0

1

1

Echo buffer descriptor

 

 

 

 

 

 

270

C141-C013

Page 274
Image 274
Fujitsu MBA3073RC, MBC2036RC, MBC2073RC, MBA3300RC, MBA3147RC specifications Read Buffer 3C, Read Buffer transfer mode