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3.4 Maintenance, Diagnostic Commands
The “Transfer byte length” field in the CDB specifies the total number of bytes of header and buffer data that can be received by the INIT. The IDD reads the data from the data buffer beginning from the byte position in the data buffer specified in the “Buffer offset” field of the CDB and continuing in order, then adds the
The format and contents of the
(3)Mode = 0, 0, 1, 0: Data only, with address specification
The data transferred to the INIT when this mode is specified is only the data which the IDD reads from the data buffer. The header is not transferred as it is in Mode = 0,0,0,0 and Mode = 0,0,0,1. In this mode, address in the data buffer can be specified in the “Buffer offset” field in the CDB.
The “Transfer byte length” field in the CDB specifies the total number of bytes of buffer data that can be received by the INIT. The IDD reads the data in order beginning from the byte position in the data buffer specified in the “Buffer address” field and transfers it to the INIT. Data transfer is completed at the point when the number of bytes of buffer data specified in the “Transfer byte length” field has been completed or transfer of the buffer data to the final byte position of the IDD’s data buffer is completed. When zero is specified in the “Transfer byte length” field, this command is terminated without executing a data transfer.
(4)Mode = 0, 0, 1, 1: Buffer descriptor
When this mode is specified, the IDD transfers only the
Bit
Byte
7
6 | 5 | 4 |
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3 | 2 | 1 |
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0
0
X’02’ Addressing Boundary
1
X’78’ Buffer Capacity (MSB)
2
X’00’ Buffer Capacity
3
X’00’ Buffer Capacity (LSB)
Figure 3.26 READ BUFFER command: buffer descriptor
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