Strange SCSI behaviour - maybe missing terminator?!?

[danbeaver]

That sounds like it will work (at over twice the price of the US eBay one)

[Zac67]

This one's fine, too: http://www.ebay.co.uk/itm/AMPHENOL-G5925733-HD68-SCSI-LVD-SE-TERMINATOR-/280955499040?pt=UK_Computing_Drive_Cables_Adapters&hash=item416a40b220

only .99 GBP

[danbeaver]

Yes, but with "P&P" it works out to the same 5 USD range. Those are the ones I use( I like the glowing LED to tell me it is working.

[JohnFante]

Thank you for the suggestions. :-)

Earlier in the post you wrote that "devices next to the ends should be supplying termpower." How can I tell if it does that?

It will be either the Quntum HD or the Plextor CD drive that will be next to the end in the chain. The Quantum just plugs in and the Plextor plugs in with an adaptor.

Do I need to buy a termpower device or do I alter the HD/CD to supply termpower?

Sorry if the question is rather silly!

[zipper]

Term Power is handled by a jumper - you just have to find it (may be marked as TP).

[Zac67]

... or the Plextor CD drive that will be next to the end in the chain. The Quantum just plugs in and the Plextor plugs in with an adaptor.

Do NOT put an old narrow SCSI device at the end of the chain. Its terminator (resistor packs are useless anyway) would only terminate the lower 8 bits of the 16 bit bus, leaving the upper half unterminated. By far the easiest way is to put a wide device on the end, otherwise you need an adapter with a 'half terminator'.

Termpower is the power supply for the terminators, they won't work without. At least one device needs to supply termpower. I usually use the two at the ends powering their own terminators or the cable terminators right next to them.

[JohnFante]

Do NOT put an old narrow SCSI device at the end of the chain. Its terminator (resistor packs are useless anyway) would only terminate the lower 8 bits of the 16 bit bus, leaving the upper half unterminated. By far the easiest way is to put a wide device on the end, otherwise you need an adapter with a 'half terminator'.

Termpower is the power supply for the terminators, they won't work without. At least one device needs to supply termpower. I usually use the two at the ends powering their own terminators or the cable terminators right next to them.

Are you thinking about the Quantum HD or the Plextor CD?

[danbeaver]

Put an active, wide Terminator on both ends of the cable. The one I picked out with the glowing LED has "Termination Power" and thus is "Active" or there would be no power to make the LED glow. No reason to invoke, "Night and Fog" in this (Nacht und Nebel).

[Zac67]

Are you thinking about the Quantum HD or the Plextor CD?

Any narrow device at the end of a wide bus is a problem.

[JohnFante]

Thanks for all the great advice. I have so far ordered the "cheap" 99p terminator.

I plan to rebuild my chain to this:

Terminator (it is an Active terminator)
CSPPC
Seagate ST150176LW 0001 - 46,5GB (where I have OS 3.9 etc.)
IBM DRHS36D 0110 - where OS4.1 is installed
CD-ROM PX-32-TS
Quantum Viking II 4,5WSE5520 (plan to install MorphOS)
Terminator (the new 99p one)

The Quantum drive has theese specs: http://support.dell.com/support/edocs/storage/Quantum4G/Specs.htm

As far as I can see it has termination power enabled by default. If I look at the specs it also has a active terminator built in but only for singled ended chains.

I am wondering if I should put the CD just after the CSPPC? Any suggestions to the the chain would be welcome.

Thank you in advance.

Specs in case you need them:

Specs for the Seagate HD:
https://www.codemicro.com/support/disc/manuals/scsi/29471c.pdf

Specs for the IBM HD
http://www.netcomdirect.com/ibmdrul36367.html

Specs for the CD:
http://www.netcomdirect.com/plpx32xsccdd.html

[Zac67]

Active single ended terminators is what you need. There are no LVD (U2W+) controllers for the Amiga.

As long as you don't try to use the termination on the CD drive it shouldn't matter where it's attached.

[mechy]

Put an active, wide Terminator on both ends of the cable. The one I picked out with the glowing LED has "Termination Power" and thus is "Active" or there would be no power to make the LED glow. No reason to invoke, "Night and Fog" in this (Nacht und Nebel).

Active termination has nothing to do with term power. Active termination means it is using a chip internally to keep the bus signal levels closer to exact. unlike passive termination which is just resistors that pull high,low etc.The led versions are handy to be sure you have power.
I have found some LVD/SE adapters will not work on the csppc, and some seem ok. Ultra wide SE adapters always work in my experience. Plain scsi 3 terminators may or may not work. i recommend sticking with ones labeled for SE ultrawide use.

Term power is usually supplied by the controller or a device on the chain. a terminator cannot supply term power. term power can be supplied anywhere on the chain.

I have to agree with other people's post. using narrow devices on the scsi chain will slow it. Its best to use all wide devices.
When using narrow devices on the end of the UW scsi chain,a "high byte" terminator(or adapter) should be used as to keep all lines properly terminated.

Plextor makes a line of scsi cdrom drives that are 68Pin ultra interfaced,these can be found used still. many were used in IBM servers.

I have used Acard 7720UW adapters with quality cf adapters and sandisk fast cf cards and managed to attain 32MB/s transfer rates on the csppc scsi. it really does scream as far as things in the amiga world go

mech

[JohnFante]

Well .... just a quick status ... and a cry for help.

I bought a active terminator on Amigabay. Removed the Quantum and put it on the end. It looked like it did the trick but I was not sure since my OS4.1 install somehow got messed up when I removed the Quantum. I therefore removed it again and put the terminator jumper on the last Plextor PX-32TS CD.

However .... now all my SCSI drives are gone in the boot menu. Nothing is there and it goes directly to the 3.1 "put a floppy in" boot menu.

I am a very afraid that I have somehow fried my SCSI controller!! :-(

Any advice/suggestions. I have removed everything from the chain except a single HD and the CD to test. But so far nothing.

HELP!!

[Zac67]

Forget about termination on a narrow (50-pin) device, it won't work. Terminate the bus with a wide device (68-pin) or a cable terminator. Using a cable terminator, you need to make sure that any on-device terminators are turned off.

[JohnFante]

Forget about termination on a narrow (50-pin) device, it won't work. Terminate the bus with a wide device (68-pin) or a cable terminator. Using a cable terminator, you need to make sure that any on-device terminators are turned off.

Well I connected all the devices again, removed the termniator jumper on the CD-drive and connected the terminator at the end of the chain.

Now my drives dos'nt even spin up :-( ... and it still goes directly to the 3.1 boot screen.

I think I have a loose connection somewhere. But where ...

I know SCSI-drives are the fastest for Amiga but my god it is a pain to setup proberly ....

[danbeaver]

To Mechy

So the internal chip in the active terminator works without any electrical power like a resistor?  It attempts to normalize the bus signal with an un-powered circuit?  Then what is the termination power used for?