archive:computers:scsi
BASIC INSTALLATION PRODCEDURE for SCSI Drives by Ryan Ramsey – June 22, 1992
All Micropolis SCSI drives come pre-formatted from the factory. There is very little that needs to be done to this type of drive besides setting up termination and SCSI ID.
SCSI ID SETTINGS
In order for the SCSI bus to be able to tell where it is getting its information from, it is neccessary for each drive to have a particular identification number. This identification number, known as the SCSI ID is set with jumpers on the back of the drive. All the drives in the SCSI chain must have a different number.
These jumpers are located inside the 24-pin connect located on the back of the drive (next to the 50-pin cable connector).
If you hold the drive with the cable connectors toward your body and the circuit board side facing upwards, you will see the power connector on the left, the 50-pin connector in the middle, and the 24-pin connector on the right.
The jumpers for the 24-pin connector are as follows:
50-Pin Connector 24-Pin Connector
______________ _________________________________________________
. . . . . . . | | o o o . . . . . . . . . . . . . . . . . . . . . |
. . . . . . . | | o o o . . . . . . . . . . . . . . . . . . . . . |
-------------/ \-----------------------------------------------/
| | |
| | ID2 (Value 4)
| |
| ID1 (Value 2)
|
ID0 (Value 1)
If this is the going to be the only drive in the system, it should be set to SCSI ID 0, which is attained by having NO jumpers in the first 3 pairs of the 24 pin connector. For every additional drive, the SCSI ID should be incremented by 1. So if you have 3 drives in the system, your primary drive should be at SCSI ID 0, your secondary at SCSI ID 1, and your final drive at SCSI id 2.
SCSI ID can be computed as follows by installing jumpers in the following pairs of pins:
SCSI ID ID0 ID1 ID2 SCSI ID ID0 ID1 ID2
------------------------ ------------------------
0 | 4 | X
1 | X 5 | X X
2 | X 6 | X X
3 | X X 7 | X X X
Each of the pairs of pins have values (as shown in the diagram). In order to get a certain SCSI id, just jumper the pins as you wish and the sum of the values is your SCSI ID. So if you have ID0 (value of 1) and ID2 (value 4) jumpered, your SCSI id will be 5.
NOTE: SCSI ID 7, should never be used. This is usually reserved for the
host adapter.
DRIVE TERMINATION
Termination is something that causes a lot of undue grief for everyone, but
the concept is really simple.
"Only the last drive in the SCSI chain must be terminated,
all others should be un-terminated."
and
"The SCSI chain must be terminated on both ends."
There are two possible termination configurations.
1. A HOST ADAPTER WITH ONLY INTERNAL OR ONLY EXTERNAL DRIVES
This is the most common configuration, and this configuration applies
to BOTH INTERNAL and EXTERNAL drives. The controller must be terminated
(which is the way it comes from 99.99% of the manufacturers) AND the
very last drive/component on the CABLE (do not get "the last drive on
the cable" confused with the "last drive, which would be the highest
SCSI ID").
Therefore, a graphic display would look as follows:
____
/ \ External OR Internal
| HOST |=====DEVICE=====DEVICE
\____/ | |
| UN-TERMINATED |
| |
TERMINATED TERMINATED
(Usually default)
So once again:
If you have only one drive, it is to be TERMINATED.
If you have more than one drive, all drives must be UN-TERMINATED
except for the last PHYSICAL drive on the CABLE which must
be TERMINATED.
2. A HOST ADAPTER WITH INTERNAL AND EXTERNAL DRIVES
This setup is a little bit trickier. If you have a host adapter that
connects internal drives as well as external drives, the HOST ADAPTER
must be UN-TERMINATED, the LAST drive on the INTERNAL cable must be
TERMINATED, and the LAST drive on the EXTERNAL cable must be
TERMINATED also.
Therefore, your configuration would look like this.
____
Internal / \ External
DEVICE====DEVICE====| HOST |====DEVICE====DEVICE
| | \____/ | |
| | | | |
| | UN-TERMINATED | |
TERMINATED | | TERMINATED
| |
UN-TERMINATED UN-TERMINATED
So once again, if you have drives on both ends of the controller card,
the controller card must be UN-TERMINATED, and the last drive on each
end of the SCSI BUS (Cable) must be TERMINATED.
CABLE INSTALLATION
Once the two above items are checked and configured, all you need to
do then is put the drive on the cable (matching the red stripe on the
cable to pin one on the controller card) and then power on.
TROUBLESHOOTING GUIDE
PROBLEM
2 drives or 7 drives are seen on the SCSI bus when only 1 drive is
installed on the controller card.
REMEDY
Your drive is set to SCSI ID 7, which is what most host adapters are
set as the default configuration. Change your SCSI id to anything
other than 7 (also, you cannot use the same ID as another drive).
PROBLEM
When booting up the system, the machine gets hung up at the bios
banner of the controller card.
REMEDY
There are a few possibilities for this problem.
1. There is a drive set to the same SCSI ID as the controller card.
Change the conflicting drive to a SCSI ID that is not in use.
2. There are two drives with the same SCSI ID.
Verify that all drives have different SCSI ID's.
3. There could be a bios conflict.
Change the bios address of the controller card to a different
memory location.
4. There could be a conflict with add in boards. Check and make sure
that there are no memory conflicts with any add in boards or
bios's, check DMA's, IRQ's, and port addresses.
PROBLEM
When you boot up, the computer gives you a message along the lines
of "Drive C not found" or "Drive 0 not found".
REMEDY
Check your system CMOS. Set both drive 0 and drive 1 to
"Not Installed" or 0. CMOS drive settings are for ESDI drives only
so if you don't have an ESDI drive, it will cause havoc on your
system.
PROBLEM
Drive does not appear to spin up or power-on.
REMEDY
Check to see if the power cable is connected and if power is actually
on. Believe it or not, this is a re-occuring problem.
If the drive still fails to spin up, check the self test seqence.
Remove the SCSI cable from the drive and power it on. On the front
of the drive there is a LED which will blink in a certain sequence.
If the drive is 'healthy' the light sequence consist of 1 long blink
and 3 short. If you get anything else or you get a repeating pattern,
then the drive may be defective and you should call our technical
support department for further advice.
If you are experienceing a problem that is not approached in this
document or you continue to have problems, you may do one of the
following:
1. Call our Technical Support Line at (818) 709-3325.
2. Call our BBS at (818) 709-3310 and leave an email to the Sysop.
3. FAX your request to us at (818) 718-5352.
4. Mail your request to:
Micropolis Corporation
Attn: Technical Support
21211 Nordhoff Street
Chatsworth, CA 91311
/home/gen.uk/domains/wiki.gen.uk/public_html/data/pages/archive/computers/scsi.txt · Last modified: 2001/11/08 10:19 by 127.0.0.1