HP C2246 Technical Reference Manual page 130

Interface Control
The INTERFACE CONTROL command allows the Initiator to send an ESDI command
directly to the disk drive ESDI interface. If this command returns a Check Condition status,
the subsequent Request Sense command will, in most cases, return a Sense Key of 01, and an
additional Sense Code of 44H, whether or not the command completed correctly. However, the
Vendor Unique DERROR status code will be valid.
Interface Control Command Descriptor Block (CDB)
Bit
Byte 7
I
6
I
5
I
4
I
3
I
2
I
1
I
0
00 Opcode= EFH
01
Logical Unit Number
I
Reserved
I
Status
02-03
(MSB=02)
Command (LSB=03)
04-08
(MSB=04)
Reserved
(LSB=08)
09 Control Byte
Status. If this byte is set to one (1), two (2) bytes of ESDI status information will be received
from the disk drive and returned to the Initiator in addition to the interface status byte
described below.
Note
•
There is no interface timeout on this command. It is the Initiator's
responsibility to issue valid commands and to set the STAT bit only for
commands which will normally return status information.
A single byte will be returned to the Initiator when the disk controller completes its
operation. The byte has the following bit definitions:
• Bit 0 - Disk drive selected
• Bit
1 -
Command complete
• Bit 2 - Ready
• Bit 3 - Attention
• Bits 4-7 - Undefined
Command. This field is the ESDI command for the disk drive.
B-10 Vendor Unique Command Descriptions