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Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: JohnFante on September 08, 2012, 11:35:20 AM
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I recently bought a A4000 with a CSPPC, CVPPC etc.
There are three HD's, two CD's and a zip drive connected to the SCSI-controller.
However I think there is a missing terminator on one end of the SCSI-chain.
I get an strange behaviour with one of the HD's when I install OS4.1 (see picture). It installs fine on one of the other HD's (not the one with the error) but my system has an tendency to lock (with only a reset as the cure) when I copy huge amount of data from one HD to another.
As far as I can see my chain is
Terminator
CSPPC
Seagate ST150176LW 0001 - 46,5GB
IBM DRHS36D 0110 - where OS4.1 is installed
CD-ROM PX-32-TS
HP35470A (ZIP)
CD-R PX-W124TS
Quantum Viking II 4,5WSE5520
I have attached a photo of the last drive (the Quantum) and as far as I can see there is no terminator after the Quatum.
Does anybody know what could be the cause of the behaviour, and do I need a proper terminator after the Quatum HD and what kind should it be?
I do not know if it is any help but SCSI-config (on 3.9) gives this:
Units:
Board 0 - Unit 1 - DRHS36D
Board 0 - Unit 2 - CD-ROM PX-32-TS
Board 0 - Unit 3 - HP35470A (ZIP)
Board 0 - Unit 4 - CD-R PX-W124TS
Board 0 - Unit 5 - ST1250176LW
Board 0 - Unit 8 - Viking II 4,5WSE5520
Thank you in advance.
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Are all these guys (devices) attached the the 68-pin cable?
At least 4 of these are SCSI 1/2, the hard drives I can't tell by looking (I'm in bed typing on my iPhone with a fat white cat on my chest). Are any of the hard drives UW160/320? These questions have nothing to do with your problem, because, YES. You near an "active, wide, LVD/SE Terminator" at the other end of the cable.
The CSPPC SCSI device can reach near 40MB/s with SCSI-3 (also known as UltraWide) supported. The SCSI 2 will slow your bus down to 10MB/s or less. The drive transfer types compatible with the SCSI 3 bus are also listed as U160 or U320; Amy may not reach those speeds, but these drives are real inexpensive off *Bay, and I've gotten 35MB/s on a windy day.
But yeah, get on the web (*Bay) and score a Terminator, and don't spend more than 10 USD for one (good ones have an LED that glows to prove its active).
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Additional info:
SCSI 1: 5MB/s. 8-bit data w/ asynchronous transmission
SCSI 2: 10MB/s 8-bit data w/ synchronous transmission
SCSI 3: Confusing, ranging from 20MB/s (50-pin) to 40 MB/s (68-pin), with speed improved by faster clock and error checking (CRC)
Wide = 16-bit data
Ultra = improved bus communication
U160/320 = MegaBits/s (not MegaBYTES/s) -- bigger numbers sound faster, but these transfers are parallel and should be referred to as bytes, leaving Bits to serial transfer
Synchronous = bytes can be sent without each bytes getting a "received signal"
CRC = cyclic redundancy check -- done on transmitted data every 8/16/32/.... Byte to assure accuracy at high transmission rates
Termination = keeps sent signal on the bus from ranging wildly with the faster the signal, the more wildly it can go; Passive is dampening using a set of resistors that can be used usually with SCSI 1/2; Active = an electrical circuit actively dampens the signal to prevent errors from fast transmission speeds. Active is ALWAYS better than passive, and is best reproduced at the cable level (my opinion).
Narrow termination = 8-bits are dampened
Wide termination = 16-bits are dampened
On a Wide cable (68-pin CSPPC) a wide terminator is needed at BOTH ends; narrow termination leave 8-bits running free and wild to represent any ole' number they wish
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UW-SCSI is very picky about termination quality, cable quality, device spacing(!) and cable length(!!). With >4 devices connected to the bus it runs a maximum of only 1.5 m.
Single Ended was abandoned beyond Ultra SCSI because of this. All later standards used Low Voltage Differential signaling.
The bus ends MUST be terminated actively (SE or LVD/SE) and the devices next to the ends should be supplying termpower. My guess is device spacing (any connectors added after manufacturing?), overall cable length or cable quality. Another possibility is a SCSI-2 device influencing the Ultra-SCSI transmissions. I've also seen bad wide-to-narrow adapters.
If you can't or don't want to change the cabling you can probably slow down CSPPC SCSI to Fast-Wide (20 MB/s max) in general to get rid of the problems. Another approach is to move the slower, non-Ultra devices to a separate bus (=controller).
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Are all these guys (devices) attached the the 68-pin cable?
At least 4 of these are SCSI 1/2, the hard drives I can't tell by looking (I'm in bed typing on my iPhone with a fat white cat on my chest). Are any of the hard drives UW160/320? These questions have nothing to do with your problem, because, YES. You near an "active, wide, LVD/SE Terminator" at the other end of the cable.
The CSPPC SCSI device can reach near 40MB/s with SCSI-3 (so known as UltraWide) supported. The SCSI 2 will slow you bus down to 10MB/s or less. The drive transfer types compatible with the SCSI 3 bus are also listed as U160 or U320; Amy won't reach those speeds, but these drives are real inexpensive used.
But yeah, get on the web (*Bay) and score a Terminator, and don't spend more than 10 USD for one (good ones have an LED that glows to prove its active).
Everything is connected to the same cable. Some have adapters so the cable can connect but that is that. One long chain.
Thanks for the advice on the terminator. Any specific suggestions for wich one?
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Yeah, what Zac67 said, kinda
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The SCSI 2 will slow your bus down to 10MB/s or less.
No. The bus will arbitrate the best speed with each device separately. Slow devices may use up a lot of bus time while they're in use, slowing down faster devices, but they do not slow down the bus in general.
The only exception to this rule is when connecting an SE device (up to Ultra SCSI) to an otherwise LVD bus (U2W+), forcing the whole bus to SE mode electrically. But there's no LVD controller for the Amiga, so this doesn't count. (There's even an exception to this exception rule when using a SCSI bridge like e.g. the Adaptec 2940U2W does.)
SCSI 1: 5MB/s. 8-bit data w/ asynchronous transmission
Not entirely correct - SCSI-1 has asynchronous (~3.5 MB/s max) and synchronous mode (5 MB/s max).
U160/320 = MegaBits/s (not MegaBYTES/s)
Nonsense - it's 160 / 320 megaBYTES/s.
Our old LTO-3 drive peaks at ~120 MB/s. 320 Mb/s would only be 40 MB/s.
Another note on termination:
Passive terminators are only supported up to Fast (Wide) SCSI. Ultra (Wide) SCSI requires active termination and U2W, U160, U320 require LVD(/SE) terminators.
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Yes, I like "68-pin active SCSI terminator -brand new FOX CONN" the price is right as is shipping -- free
Some places want up to 60 USD For these
Sorry Zac, you are right it is megabytes; please note it is 6am here, I've been up all night and there is a heavy animal sitting on my chest
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Zac, as I said earlier, "To err is human, to forgive is unexpected."
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Well, maybe you should get rid of that feline hulk... ;)
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Zac, this is unconditional love!
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Thank you for your help.
I think I will take the ZIP and CD-burner of the chain and get a new terminator.
Can anybody recommend any good ones that you can buy online (a link would be nice :-))?
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Sorry,
Links are problematic on the iPhone
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Could I use something like this?:
http://www.ebay.co.uk/itm/SCSI-3-Half-pitch-68-male-active-terminator-Ultra-Wide-/130592807947?pt=UK_Computing_Drive_Cables_Adapters&hash=item1e67f01c0b
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That sounds like it will work (at over twice the price of the US eBay one)
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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
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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.
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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!
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Term Power is handled by a jumper - you just have to find it (may be marked as TP).
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... 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.
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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?
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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).
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Are you thinking about the Quantum HD or the Plextor CD?
Any narrow device at the end of a wide bus is a problem.
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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
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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.
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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
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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!!
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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.
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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 ....
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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?
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All terminators require termpower, regardless of type. At least one device needs to supply TP.
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Well that clears up the Active vs Passive question
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how's you getting on dan? i shouldn't think you've fried the cyberstorm... maybe if you put just the two hard disks on the chain, physically either side of the cyberstorm, and set the drives to terminate, this should terminate the bus without the worry of narrow devices, or possibly dodgy terminators.
do they show in early startup?
once you have one or two devices showing, then add the rest one at a time...
i remember having devices on the bus for the sake of it. zip, jaz, RW MagnetoOptical, yadda yadda. do you really need a zip drive? and two hard disks? can you not consolidate?
just thinking "out loud" :) best of luck!
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how's you getting on dan? i shouldn't think you've fried the cyberstorm... maybe if you put just the two hard disks on the chain, physically either side of the cyberstorm, and set the drives to terminate, this should terminate the bus without the worry of narrow devices, or possibly dodgy terminators.
do they show in early startup?
once you have one or two devices showing, then add the rest one at a time...
i remember having devices on the bus for the sake of it. zip, jaz, RW MagnetoOptical, yadda yadda. do you really need a zip drive? and two hard disks? can you not consolidate?
just thinking "out loud" :) best of luck!
Its not Dan's problem :-) as far as I know ....
Good to know that I "probably" havn't fried the Cyberstorm. I must admit I am rather concerned thou. I disassembled all the drives. Checked the SCSI-id's, the jumpers and the power cables (as good as I could) and put in the two HD's and the CD-rom and the terminator in the end.
Still nothing. The HD's dos'nt spin up anymore and the system goes to the floppy boot.
I will try with only one HD but to be honest I am not very optimistic. I think I need some physical assistance to sort this one out.
I will get back when I - hopefully - find the solution.
Thank you for all the help.
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WOOOHOOOO!
Things are running again. :-D
When I removed the CD-ROM (Plextor PX-32TSi) so I only had the two HD's (Seagate and IBM) and a terminator at the end the HD's spinned up and I was able to boot my OS4.1 install.
And as far as I can feel the HD's works a little bit faster with the Quantum drive of the chain.
Now I only need to get the correct jumper settings for my CD-ROM drive to solve the conflict I have.
Anybody have any experience with how to correctly configure a Plextor PX-32TSi CD-ROM drive or a Plextor-W124TSi CD-RW drive?
Thank you in advance.
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Dunno about Plextor, but there's usually a TE jumper (for Terminator Enable) - remove. PE is Parity Enable (you'll want that on), TP Term Power (don't need it, remove). The ID must be unique, of course.
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JF, I know you didn't ask, so take this as unsolicited info: the Acard 7720UW (100 USD) will allow a wide-to-IDE conversion for a new DVD-RW drive at full 2012 speed on your CSPPC bus and white ones to match your Amiga are available.
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WOOOHOOOO!
Things are running again. :-D
When I removed the CD-ROM (Plextor PX-32TSi) so I only had the two HD's (Seagate and IBM) and a terminator at the end the HD's spinned up and I was able to boot my OS4.1 install.
And as far as I can feel the HD's works a little bit faster with the Quantum drive of the chain.
Now I only need to get the correct jumper settings for my CD-ROM drive to solve the conflict I have.
Anybody have any experience with how to correctly configure a Plextor PX-32TSi CD-ROM drive or a Plextor-W124TSi CD-RW drive?
Thank you in advance.
Just set the jumpers so it is a device between 0-6 and does not conflict with another drives on the chain(remember each scsi drive has to be a diff. number). then set termination on or off depending where it is on the chain. generally i set the hard drive numbers lower and the cd after those. the jumper settings are usually on the back of the cover or label.
putting 50 pin narrow scsi drives on the ultrawide 68 pin chain will generally slow everything down. Plextor did make 68Pin cdroms also.
mech
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Heh, woops, sorry, my bad,
glad things are running again! i've not had good expiriences with 50 pin to 68 pin adapters, and an old friend had so many issues with 50 pin devices, he ended up getting an A4091 scsi card to run them.
at the time i had an A4kT, so could string them off the onboard scsi, and leave the fast hard disks to the PPC's scsi.
i know it doesn't help you much, but just an anecdote from my expirience.
on a side note, i was having massive issues with the scsi chain i had on my PPC1200. turned out it was the Plextor CD/RW had finaly given up the ghost. i thought they were indestructable. but it turns out that no matter what i did with the termination or IDs, everything was rosey once i took the plextor out of the loop. so i'm at a loss as to what's going on there. maybe something similar is/was happening to your setup?
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Again, nothing in this post will solve your issue, but since the last "unit" on the bus/chain is designated by its ID number and the controller wants to know the last device and last unit number, I have always felt that it should be a drive where this is recorded in its RDB; so I use a HDD there and a CD earlier.
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Again, nothing in this post will solve your issue, but since the last "unit" on the bus/chain is designated by its ID number and the controller wants to know the last device and last unit number, I have always felt that it should be a drive where this is recorded in its RDB; so I use a HDD there and a CD earlier.
Not sure what you mean here,but setting last unit i.e. in hdtoolbox is just to keep it from wasting time scanning past that ID - you can also set last LUN iirc. that value is written to the RDB.
Since scanning starts at ID 0 it makes sense to have the boot drive low as possible for quicker booting.
A narrow scsi controller actually does not care what the last number is and doesn't need to know.. if no last id is set,on narrow scsi it will scan 0-6 (controller usually 7) and on UWscsi supports 15 devices.
Now in scsi,termination wise the last drive doesn't care what number it is,its just the last drive physically on the last connector.(i know this has nothing to do with what you said above,just a FYI here).
Putting a cd early also slows things since cd's come on the bus slower than the average HD(not always-but in many cases..) In the reality of things this may not make enough difference to change it.
Some like to put the hd at ID 0 and the cdrom at ID5,i never really understood this,makes more sense to me to do ID0 for the hd and say ID1 for the cdrom if its the only other device.
Setting LASTID sometimes can be a pain,if you add a device past the last ID,and forget to edit the rbd to scan to the lastID,then you set there wondering why it doesnt see the drive you added.. lol.
Mech
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It appears to me before booting the SCSI controller scans the entire bus querying each ID (and LUN) before it does any booting. Also whenever I change a device (CF Card added or removed at end of chain -- something I no longer do) when I go to HDToolBox or Media Toolbox I get a "need to update drive" request dealing with Last ID / LUN. From this I inferred that the controller wants to be able to write this info into the RDB or someplace on the drive; hence a CDROM would have no place to write this.
In addition how can an active terminator circuit "actively dampen" a signal without a power supply? A resistor uses the power of the signal itself to reduce that signals amount of voltage, but a circuit that attends to do a proper reduction of a signal voltage should itself be powered. If so, how can it do that without, lets say for the sake of argument, without termination power. If it does so with another power source, what is then the termination power used for? I'm not an electrical engineer and I think in terms of digital rather than analogue, but a simple transistor setup to dampen an excessive signal voltage still needs a separate power supply, or is there another way around this?
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It appears to me before booting the SCSI controller scans the entire bus querying each ID (and LUN) before it does any booting. Also whenever I change a device (CF Card added or removed at end of chain -- something I no longer do) when I go to HDToolBox or Media Toolbox I get a "need to update drive" request dealing with Last ID / LUN. From this I inferred that the controller wants to be able to write this info into the RDB or someplace on the drive; hence a CDROM would have no place to write this
Dan,
It will write the last id to the boot drives RDB to what the last drive now is in this case.It would not try to write it to a cdrom of course since its a read only removable as far as i know.
mech
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Yes, that was my point; it can't write last anything to a CDROM so it just keeps checking all the IDs and LUNs.
Any help with the rest of the post on how active termination circuits work without power?
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Yes, that was my point; it can't write last anything to a CDROM so it just keeps checking all the IDs and LUNs.
Any help with the rest of the post on how active termination circuits work without power?
i guess i misunderstood what you were saying about the cdrom.
on the terminators, Someone else answered that for you earlier(Zac iirc), but the answer is they dont,you always need term power or terminators do not work :)
most active terminators use a custom chip to keep bus levels right,it of course also needs power.
Mike
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Active termination has nothing to do with term power.
mech
Herein lies my problem, if the active termination circuits don't have anything to do with the "term[ination] power" then what or where comes the power used to keep them, well, "active?"
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As far I can see there are two causes of the problem:
There is some kind of conflict between my Plextor CD-Rom drives and the rest. Probably a dodgy terminator.
I lack terminator power. And I think this is the real culprit.
My two HD's have SCSI-ID 0 and 1. I have set the ID for the CD-drive to 2, turned on parity, turned of termination. See the attached photo for a detailed layout of the jumpers.
Both drives (I have tried them individually) show the same error. When I try to boot my drives dosn't spin up and I go directly to the Kickstart 3.1 bootmenu.
The Seagate HD (wich has ID 0 and is first in the chain) has a jumper for termination power. At the moment it is off.
The IBM HD (which has ID 1 and is the second in the chain) dos not have the ability to supply termination power. Only the 68SE model has that and mine is not that. It connects through a rather strange interface. Se photo.
Can I enable termination power on the first drive (Seagate) without risking to cause damage? Or do I have to move it to the last place before the terminator?
If I do not move it the chain would then be:
Active terminator
CSPPC
Seagate HD (with termination power enabled)
IBM HD
CD-ROM
Active terminator
Thank you in advance.
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The pic on the right is an SCA adapter. SCA is an interface intended for connecting into a backplane, there's no termination or termpower provided (there are some SCA adapters with terminators but this isn't one).
Termpower is often provided by several devices but I've had - rare - occasions when that was a problem somehow (which I can't explain I'm afraid). Best practice is to provide termpower by the host adapter and if that isn't possible from the devices at the end of the bus, near the terminators. Terminators with an LED have the advantage of showing you whether termpower's present.
SCSI IDs: the RDB 'last drive' option just stops scanning further drives for RDB automount purposes, so it's perfectly reasonable to put an optical drive on higher IDs. I'm running my boot drive on ID1, so I can add a temporary drive at ID0 without having to fiddle with HDToolBox. Opticals (if present) are on 4 & 5, a tape on 3. 6 I reserve for a 2nd host adapter (PC side) but I haven't 'SCSI-netted' for ages.
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Herein lies my problem, if the active termination circuits don't have anything to do with the "term[ination] power" then what or where comes the power used to keep them, well, "active?"
both active and passive terminators use term power.
Passive terminators are a bunch of resistors from the bus lines to term power.
Active terminators are similar, but as well as pull up resistors they have voltage regulators.
Wikipedia has a bit more detail
Parallel SCSI buses must always be terminated at both ends to ensure reliable operation. Without termination, data transitions would reflect back from the ends of the bus causing pulse distortion and potential data loss.
A positive DC termination voltage is provided by one or more devices on the bus, typically the initiator(s). This positive voltage is called TERMPOWER and is usually around +4.3 volts. TERMPOWER is normally generated by a diode connection to +5.0 volts. This is called a diode-OR circuit (http://en.wikipedia.org/wiki/Diode-or_circuit), designed to prevent backflow of current to the supplying device. A device that supplies TERMPOWER must be able to provide up to 900 mA (single-ended SCSI) or 600 mA (differential SCSI).
Some early disk drives included internal terminators, but most modern disk-drives do not provide termination which is then deemed to be external.
Termination can be passive or active. Passive termination means that each signal line is terminated by two resistors, 220 Ω to TERMPOWER and 330 Ω to ground. Active termination means that there is a small voltage regulator which provides a +3.3 V supply. Each signal line is then terminated by a 110 Ω resistor to the +3.3 V supply. Active termination provides a better impedance match than passive termination because most flat ribbon cables have a characteristic impedance (http://en.wikipedia.org/wiki/Characteristic_impedance) of approximately 110 Ω. Forced perfect termination (FPT) is similar to active termination, but with added diode clamp circuits which absorb any residual voltage overshoot or undershoot.
No term power, no termination. I doubt you can cause damage from enabling term power on any of the devices, no matter where they are on the bus. The only problem I could imagine would be a voltage drop, but the regulator in an active terminator will sort that out.
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Well I moved the HD's so that the chain is as follows:
Active terminator
CSPPC
IBM ID0 - no term power
Seagate ID1 - term power
CD-ROM ID2 - no term power
Active terminator
When I have that chain I still go to the kickstart 3.1 boot menu.
When I remove the CD-ROM it boots into OS4.1 fine (placed on the IBM).
I most admit I am loosing hope here. Once during my fideling around I got the CD to work. Then I put all hardware in its places and changed som ID jumpers and then it didn't work again. Do not know why? :-(
I have an old IDE DVD-drive laying around. Can I use that on the IDE channel? I know it is not that fast but since I am will not be using it for anything but installation that would be just fine.
SCSI kind a suck right now ....
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Herein lies my problem, if the active termination circuits don't have anything to do with the "term[ination] power" then what or where comes the power used to keep them, well, "active?"
i think you misunderstood what i meant :) i was saying they are 2 seperate things. some people comfuse term power as termination etc.
Some people don't realize what term power was for.
mech
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Well I moved the HD's so that the chain is as follows:
Active terminator
CSPPC
IBM ID0 - no term power
Seagate ID1 - term power
CD-ROM ID2 - no term power
Active terminator
When I have that chain I still go to the kickstart 3.1 boot menu.
When I remove the CD-ROM it boots into OS4.1 fine (placed on the IBM).
I most admit I am loosing hope here. Once during my fideling around I got the CD to work. Then I put all hardware in its places and changed som ID jumpers and then it didn't work again. Do not know why? :-(
I have an old IDE DVD-drive laying around. Can I use that on the IDE channel? I know it is not that fast but since I am will not be using it for anything but installation that would be just fine.
SCSI kind a suck right now ....
Is the cdrom a 68pin cdrom or are you trying to adopt a 50pin cdrom to a 68pin UWscsi chain?
Have you went into the csppc early menu and checked the scsi setting? perhaps something is off? You might set everything to auto until you get up and running.
Maybe the cdrom drive is bad? 15-20 year old scsi drives do fail sometimes.
You could use a cd/dvd drive on the internal ide with no problems. it will be slow,but as you say, something is better than nothing. Be sure to set it as master if its the only ide device.
Mech
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Is the cdrom a 68pin cdrom or are you trying to adopt a 50pin cdrom to a 68pin UWscsi chain?
It is a 50pin CD-ROM with a 68pin to 50pin converter. It is a Plextor PX.32TS. Se photo. Just to be clear. It has worked fine but has stopped working because I removed a HD, attached a terminator etc.
Have you went into the csppc early menu and checked the scsi setting? perhaps something is off? You might set everything to auto until you get up and running.
I have set everything to auto. No result
Maybe the cdrom drive is bad? 15-20 year old scsi drives do fail sometimes.
I have thought about that but since it has worked flawlessly until now combined with the fact that It worked very shortly during my "fideling" and the fact that I get the same error when I use a Plextor PX-W124TS CD-ROW dirve I would say that it is unlikely.
You could use a cd/dvd drive on the internal ide with no problems. it will be slow,but as you say, something is better than nothing. Be sure to set it as master if its the only ide device.
Great :-) I will dig one out and see what happends.
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It is a 50pin CD-ROM with a 68pin to 50pin converter. It is a Plextor PX.32TS. Se photo. Just to be clear. It has worked fine but has stopped working because I removed a HD, attached a terminator etc.
I have set everything to auto. No result
I have thought about that but since it has worked flawlessly until now combined with the fact that It worked very shortly during my "fideling" and the fact that I get the same error when I use a Plextor PX-W124TS CD-ROW dirve I would say that it is unlikely.
Great :-) I will dig one out and see what happends.
I think i see the trouble, you should be using a 68 to 50 adapter with high byte termination. The picture you have seems to show a regular 68/50 adapter.
Mech
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When a narrow device is connected somwhere in the middle you can simply use an ordinary adapter.
Only if you connect that device to an end and need it to provide termination (no cable terminator) then you need a half-terminating adapter to take care of the high byte. ;)
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When a narrow device is connected somwhere in the middle you can simply use an ordinary adapter.
Only if you connect that device to an end and need it to provide termination (no cable terminator) then you need a half-terminating adapter to take care of the high byte. ;)
I moved the CD-ROM to the middle of the chain and changed the ID's so that it is:
Active terminator
CSPPC
IBM ID0 - no term power
CD-ROM ID2 - no term power
Seagate ID5 - term power
Active terminator
Stil the same. :-(
Maybe my terminator is no good? It has no LED so I can not see if it has termination power. But when I remove it (and the CD-ROM) my system will not boot so it must be doing someting.
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Just a quick thought after I browsed for help.
Do the HD's have to be set for single ended? There is a jumper on both that can force single ended. At the moment they are off.
The drives are a IBMDRHS-36D and a Seagate ST150176LW.
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Just a quick thought after I browsed for help.
Do the HD's have to be set for single ended? There is a jumper on both that can force single ended. At the moment they are off.
Yes!!!
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Single Ended was abandoned beyond Ultra SCSI because of this. All later standards used Low Voltage Differential signaling.
And you can't mix SE and LVD on the same bus. Back when SCSI was popular you'd get servers with an UWSCSI raid controller for the harddrives and another SCSI2 controller for running the optical drives.
If you've still not got it sorted and you want to have them on the same bus then you will need to read up alot more on SCSI and do some trial an error adding and removing devices.
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And you can't mix SE and LVD on the same bus. Back when SCSI was popular you'd get servers with an UWSCSI raid controller for the harddrives and another SCSI2 controller for running the optical drives.
If you've still not got it sorted and you want to have them on the same bus then you will need to read up alot more on SCSI and do some trial an error adding and removing devices.
My HD's kan do both SE and LVD.
I will se if forcing SE gives any result. If not then I will switch to a IDE CD-ROM and give my SCSI-problem a rest and read up on SCSI.
I am a bit tired off moving drives and jumpers around .... :-)
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Well changing the jumpers to force single ended did'nt make any difference.
I have now installed a old IDE CD-ROM and it works flawlessly in OS4.1. Worked out of the box.
Somewhere along my fideling my OS3.9 install broke. And since my OS3.9 boot disk was created with my SCSI CD-ROM I get an error when I try to use it. Any suggestions on how to change a Emergency boot floppy from SCSI CD to IDE CD?
And last but not least thank you very much for all your help. :-D
I will get back back if I - eventually - find a solution to my SCSI-problem.
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And you can't mix SE and LVD on the same bus.
Yes, you can - it may or may not be smart though. A SCSI bus with a single SE device connected to it forces the bus to SE electrically: all return lines are grounded. Unless any of your LVD devices has a problem with SE in general (some - rare - are LVD only, not LVD/SE), everything is fine at UW speed (unless cable length for that mode is exceeded). Since the CSPPC is SE to start with, there's little to gain by forcing SE somewhere else.
On some PC HBAs there were even SCSI bridges to get an SE and an LVD domain in a single bus (e.g. AHA2940U2W).