#SCSI Problems!!
18 messages in this thread
Pardon this intrusion of the thread,
My Bernoulli box (external) is the last device in my chain.
If it's hooked up but not on, I assume then that my SCSI chain is not
terminated.. True ?
Rocky
I don't know whether a powered-down device hangs the bus because of
termination or for some other reason, but the practical result is the same
– bus no workee.
Dale L. Larson Intangible Assets Manufacturing (info@iam.com)
"That's the best part about being crazy. You see things no one else can see."
Dale,
Actually I just found a problem I've been having since I got my
Bernoulli.
Randomly the computer would dance around the hard drive for sometimes a
full minute before locking on to the boot sector and booting.
Well yesterday every program that accessed one of my internal hard drives
locked up the system.
Finally after a lot of research ( as in RTFM ) I found that my chain was
in fact bogus.
Prior to the external bernoulli I had the Zeus Scsi card terminated and
the furthest drive terminated also. When I added the Box I just remove the
termination from the last internal drive and terminated the BOX.
Now I see that the manual says when you have internal and external drives
the SCSI card is no longer at the end of the chain but in the middle. Now
it looks like this:
Box – SCSI Card – INternal – Internal
As it says the chain is now formed from the furthest external device to
the card and the other end is from the furthest internal drive to the
card.
Live and learn
Incidentally if I power the amiga up while the box has a disk in it those
icons remain forever even after I change disks in the Bernoulli. However,
if I power up the amiga with the Box running but without a disk in it then
the icons come and go as you change them.
Thanks
Rocky
Rocky, you should get the SCSIMount utility. It will help solve all those
mounting wierdnesses.
DJ
DJ,
I'm not familiar with the SCSIMount utility you mention. What where is it
? Even though I seem to have everything working fine now.
Rocky
Rocky, it goes out to the SCSI bus and checks for available drives, then
allows you mount and dismount at will. Very handy for using drives that
were not up at boot time, or when changing media with different boot block
configurations (i.e. partitions). I for get if it's in the Tech or User
section.
DJ
Rocky –
You seem to be having success with your Zeus and SCSI. Including using
removable media with it. We're running a SCSI-II gigabyte drive mounted ON
the Zeus, but have not had much luck attaching other devices.
On the other hand, we got it used, and I'm not sure we have all the
documentation, and I was not sure the Zeus understood removable media
devices. Our device version for the Zeus is 2.985. Yours?
If I understand you correctly, you are saying that the Zeus card is
logically in the MIDDLE of the chain, with internal devices going one way
from it and external devices forming the other end of the chain. And, of
course, only the last internal and the last external device should be
terminated.
Theoretically, this means that the card should be terminated if there is
no external device; however, with some boards, if there is ONLY the board
and one device, or only internal devices, having terminators ONLY on the
last internal device works. This is relevant if, for example, the only
external device is sometimes attached to THIS machine, and sometimes to
the OTHER machine in the other room (a tape backup, for example, or a
removable-media device).
Do you know whether or not the Zeus works with the INTERNAL chain
terminated, NO external chain, and the terminators REMOVED from the card?
Have you found any board incompatibilities: i.e., other cards that won't
work with the Zeus, or will only work in certain slots?
TIA for any help you can offer!
. . . . JimDoc, on AutoPilot
Jim,
Yes my version rom is 2.98.
Here's the solution.
With the card and one internal only:
Terminate both the card and drive.
Card + Several internals:
Terminate the card and last drive.(First drive is the one on the
card.)
Card + One External No internal.
Terminate the card and the external.
Card + One or more internals + one or more Externals.
Terminate the last External and Terminate the last Internal.
– Last always means furthest from the card.
You should have no trouble with using the Zeus and removable media. You
should have a software disk from PPI. It has a SCSI tools drawer with a
specific file in it for setup of devices and partitioning software etc. It
works quite well. It also has an Icon to insert in your WBstartup drawer
called "Removable". This is for the Bernoulli (Syquest too I guess. I use
a Bernoulli.)
With the Removable device in the startup and no disk in the Bernoulli (yet
the Bernoulli being powered) I can insert and remove Bernoulli disks and
their disk icons come and go from the Bench as I change them. However it
seems that if I boot with a disk actually in the Bernoulli, then the OS
keeps the icon there with ???? under it when I remove the disk. So I just
always initially boot with the drive empty.
The only other problem I have with the Bernoulli is that Quarterback
doesn't work using it as a removeable media. I have to just back up to
AmigaDosFile on the Bernoulli. This works like a champ.
If you don't have the mentioned PPI disk with your Zeus Card Let me know
right away. I am flying out of here tomorrow pm and will get you a
diskcopy in the mail right away.
Rocky
Rocky –
> You should have no trouble with using the Zeus and removable media.
You are correct, but I misstated the requirement. I meant TAPE, not
removables.
. . . . JimDoc, on AutoPilot
My Zeus does not like to see ANY termination on the external devices, period!
And it doesn't seem to care about the internal HD I have bolted to the Zeus
board itself as the SCSI chain is so short in that direction it doesn't HAVE to
be terminated anyway. If I leave things that way, all works well, even
multiple external drives on the Zeus. Just none with any terminators at all.
Weird.
whether a powered-down SCSI device supplies termination depends on the way the
device's termination is actually handled. Some devices supply their own
termiation power – and must be ON to supply it for proper termination. Others
get their termination power from the SCSI bus. Those may indeed still be
terminated even when OFF. See the detailed references to jumpers for the
particular device in its manual. I have seen many different ways various
devices (HD's, tape units, etc.) do this kind of thing. There's more here than
meets the eye. If you simply do it the same way on all your devices, then
they'll at least all behave the same (i.e., if device OFF, termination not
there, etc.). I decided to solve the whole thing with a nice long ribbon cable
that has numerous 50pin IDC connectors and a single female centronics connector
at the far end. I plug a 'external' mac-type terminator device into the
centronics and remove ALL terminators from all my devices in the chain. The
chain is ALWAYS terminated and I can plug and unplug devices at will. That
external terminator block just hangs at the end of the cable and always keeps
things kosher.
Jerry,
It depends. One of the devices is required to supply termination power
(+5v)…but it can be any of the devices on the bus. The terminators
themselves are passive (simply resistors), so if some device other than the
Bernoulli is supplying the termination power…then the fact that the Bernoulli
is on or off will make no difference at all.
I would give it about a 90% certainty that your host adapter (the SCSI
adapter in your Amiga) is supplying the termination power.
Don
Don,
Right about the adapter. See my message to Dale.
Now the adapter is not terminated and everything works fine again. It
still seems strange to me though. I would think that the adapter would
always be at one end of the chain since everything starts from there.
It got so bad I couldn't even format the one internal hard drive.
I also read that the SCSI ribbon cable should never touch anything which
is grounded such as the case. Supposedly this will change the resistance
by 40 ohms or so and weaken the scsi signal possibly causing bad writes
etc.
Well in my overstocked 2000 there is no way that cable isn't going to lie
across something which is grounded. As it is now, it lays across one hard
drive itself, which certainly finds ground through the mounting.
Rocky
Rocky,
No…the adapter is just another device and can sit anywhere in the
chain. And likewise, no, routing of the SCSI cable near the chassis should
make 0 difference. The SCSI cable (actually…the cable is the SCSI bus
itself) has a ground alternating with a signal wire every other wire.
Don
Don,
I agree it doesn't seem to matter. It was just something which was deemed
important in the Progressive Peripherals sheet on mounting SCSI devices
with the Zeus card.
Rocky
An unpowered device should not affect the others if the connections and
terminations are all OK. Remember that there are terminations at each end
of the chain, the controller being one and the last drive the other.
DJ
Maybe I misremember, but it seems like several setups in which I've had
external, powered SCSI devices, I couldn't boot without power to those
devices.
By the way, DEC, at least, recomends that all devices which can provide
termination power should. They claim it improves reliability.
Dale L. Larson Intangible Assets Manufacturing (info@iam.com)
"That's the best part about being crazy. You see things no one else can see."
Dale, like dieting and entertainment, it probably varies with each setup,
right? I have an external Syquest 270 hooked to my 3000 and have no
problems booting with it powered off, which is often. Yes, the lines
between science, art and mumbo-jumbo are rather thin …
I used to have a Zilog Unix Tower, which used the WE32100 CPU, and had six
foot ribbon cables connecting an external 5.25" drive. Never gave me a
problem. Now Wayne gets to hang his cloths on it whenever he's up here.
DJ