Need help with Seagate ST11200N 1 GByte drive

[Stanley Perkins]

I have just tried to install a second Seagate ST11200N 1 GB drive in my
elderly Mac IIfx. With the new drive hooked to the internal SCSI bus and
powered up but not yet formatted, its presence kept the Mac from
recognizing the original ST11200N, so the Mac wouldn't boot. (Yes, the
drives were at different SCSI addresses and only the last drive on the bus
was terminated.)

While this was going on, the drives appeared to "interact" with one
another, as the drive LEDs would flash on and off in alternation with each
other (or so it seemed) and I would hear each drive spin up and spin down
in alternation.

Ultimately, I was able to boot the Mac with the new drive on the bus but
unpowered, then format the new drive by powering it up and mounting it
after the Mac had booted. After I had formatted the new drive, things
seemed okay, except that occasionally the SCSI bus would hang and require
rebooting.

Comparing the two drives, the only difference I can see (other than serial
numbers and SCSI addresses) is that the original drive has a single jumper
on the header block on the "front" of the drive (near the LED) on the
third pair of pins from the left. There are no other jumpers on this
block, and none whatsoever on the header block on the new drive. After
noting the location of the jumper on the original drive, I removed it, in
the hopes it would eliminate the interaction of the drives (since the new
drive came without a jumper anyway, and I don't know the origin or reason
for the jumper on the old drive).

What was the interaction between the drives caused by (before the new one
was formatted)?

What are the functions of the jumpers on the header block on the front
of the drive? Should I install jumpers on any of them?

Is there some sort of SCSI conflict or interaction between these drives
causing the occasional bus hang?

Thanks in advance for your help. Please reply to my e-mail address, as I
don't usually frequent this newsgroup.

Regards,
Stan

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| Stan Perkins | ASMG, Inc. |
| st...@netcom.com | 619-490-9074 |
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