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AST RESEARCH, INC.        TECHNICAL BULLETIN # 1078                 3-2-95

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			 MANHATTAN P AND INCORRECT SCSI ID ASSIGNMENTS


PROBLEM
A SCSI disk drive displays an incorrect ID.  For example, a SCSI disk drive 
that is configured as ID #1 is seen by the computer system as ID #4.

CAUSE
The SCSI ID cable that connects between the SCSI disk drive and Mounting Tray 
Kit PCB is installed incorrectly.

SYSTEMS AFFECTED
AST PART NUMBER AND DESCRIPTION
		
501502-XXX     Manhattan P5090                    All Models
501503-XXX     Manhattan P5100                    All Models
500889-XXX     Manhattan XP Expansion Chassis     All Models

BACKGROUND
In order for the hot-replacement and hot-standby features to function properly, 
all physical disk drives must be configured in a Mounting Tray Kit.  
Configuring the disk drive with the kit consists of:

	1.  Securing the disk drive to the Mounting Tray chassis.
	2.  Connecting the 50 pin SCSI signal cable to the disk drive.
	3.  Connecting the power cable to the disk drive.
	4.  Connecting the ID cable.

One end of the ID cable connects to the SCSI ID address pins at the disk drive.  
Mating the cable properly consists of matching the red stripe on the cable to 
the Least Significant Bit of the ID address.  The other end of the ID cable 
connects to location J4 on the Mounting Tray's PCB.  Mating the cable properly 
consists of matching the red stripe on the cable to the Least Significant Bit 
of J4.  The Least Significant Bit at J4 is denoted by the numeral "1" on the 
silk-screen next to J4.

SOLUTION
Install the SCSI ID cable that connects between the SCSI disk drive and 
Mounting Tray Kit PCB correctly.  To do this, locate the end of the SCSI ID 
cable that connects to J4 of the Tray Kit PCB.  Unplug and rotate the end of 
the cable 180 degrees, then re-install it at J4.  After the cable has been 
rotated, the red stripe on the cable will be located at the Most Significant 
Bit of J4.   

Note: To date, AST has verified that the Quantum 1080s SCSI disk drive requires 
the SCSI ID cable to be configured so that the red stripe on the cable is 
installed mating with the Least Significant Bit of J4.  All other disk drives 
must be configured so that the red stripe on the cable is installed to mate 
with the Most Significant Bit of J4.