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Bits 6 and 7 indicate the type of trace information provided.
Bit 07
Bit 06
Trace
0
0
SCSI Bus Trace
1
0
SCSI Command Trace
13
1
SCSI Status Trace
The SCSI Bus Trace provides information on a transaction across
the SCSI bus.
This information is contained in bits 0- 5.
Bit
5
Bit 4
Bit
3
Bit 2
Bit 1
Bit 0
Information
0
0
0
0
0
0
Host Selection
0
0
0
0
1
0
Reconnection
0
0
0
0
1
1
Disconnection
0
0
0
1
0
0
Attention
Handling
0
0
0
1
0
1
Command
Linking
0
0
0
1
1
0
Command End
0
0
0
1
1
1
SCSI Reset
0
0
1
0
0
0
Bus Device
The
SCSI
Status
Trace
provides
the
completion status byte
presented in Bits 0-5.
The SCSI Command Trace provides the Command Operation Byte (Byte
00 H of COB) received.
Byte 0l H contains the Device and Host Adapter SCSI IO numbers.
These are the preconfigured SCSI bus addresses.
Trace storage is organized beginning with
2 bytes of trace
pointer followed by the wrap-around trace buffer.
The trace
pointer, in the first two bytes returned, points to the address
of the "tail" point of the buffer.
Trace information is ordered
chronologically from the "tail" pointer, through to the top of
the buffer (8000 H or COOO H ) and back around to 1 minus the "tail"
pointer address.
6-49
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