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For initiator mode CCBs, the CDB provided by the host is transmitted to the target. For Target Mode CCBs, the CDB provided from the initiator is returned to the host in this space. Byte 18+n - 18+n+m : Allocated for Sense Data If a check status condition is detected by the AHA-1740A/1742A/1744 as it completes an operation on the SCSI bus, the host adapter automatically executes a Request Sense command with the data length specified by request sense allocation length. The actual bytes returned, up to the maximum indicated by the request sense allocation length, are placed in the area allocated for sense data. If the request sense allocation length was 01h, no Request Sense command is executed. If the Request Sense command completed without a check status condition, the target status will be set to check status, and the host status will be set to 00h. If the Request Sense command completed with check status, the target status will be set to check status, and the host status will be set to 14h. If a check condition is detected by the AHA-1740A/1742A/1744 while it is operating in processor Target Mode, the same information that will later be recovered by the initiator that received the check status is also placed in the area allocated for sense data so that the host processor is also aware of the failure. adaptec AHA-1740A/1742A/1744 Scatter/Gather List Definition Using the normal CCB operation codes of 00h and 01h (SCSI Initiator and SCSI Target CCBs), the CCB itself contains a pointer to the first byte of a contiguous area of data of a specified length. The direction of transfer with respect to the data area and the checking of the length of the data transfer to the data area are both managed by the AHA-1740A/1742A/1744 according to the requirements of the particular mode and control bit set-up. Using the Scatter/Gather Operation Code of 02h or 04h, the CCB instead contains a pointer to a list of data segments and an indication of the length of the list of data segments. The data segment list contains pointers to the actual location in host memory of the data segments to be transferred as well as a precise indication of the length of each data segment. Each data segment list entry contains a 3-byte pointer to the location of a data segment and 3-byte length indicator telling how long that particular data segment shall be. The data segment list is arranged in the order in which data will be gathered or distributed, the first pointer in the list being used first. A typical data segment list is shown in the following table. The data segment list describes the distribution of 4096 bytes distributed in four separate locations within the memory. The beginning of the data segment list is indicated by the data segment list pointer. The length of the data segment list (24 bytes) will be contained in the data segment list length field of the CCB. 3 Bytes 3 Bytes Data Segment List Pointer (MSB) (LSB) (MSB) (LSB) Segment 0 L=1024 Data Segment 0 Pointer Se...