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What scsi card between aha-2940uw and 29160

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Reply 20 of 26, by ElectroSoldier

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Get an LVD cable (ebay U160 SCSI cable, or U320 SCSI cable) that has a terminator on the end of the cable and plug the drive into the HBA, then go into its BIOS and see what mode it is running in. Then you will know if its SE or LVD and what rate its transferring at.

Reply 21 of 26, by mkarcher

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ElectroSoldier wrote on 2024-09-02, 13:58:

Get an LVD cable (ebay U160 SCSI cable, or U320 SCSI cable) that has a terminator on the end of the cable and plug the drive into the HBA, then go into its BIOS and see what mode it is running in. Then you will know if its SE or LVD and what rate its transferring at.

With some SCA adapters, which do not connect DIFFSENS (but see next paragraph), you might run into issues with that test. The connection between DIFFSENS on the bus and DIFFSENS at the device is the tool used to negotiate LVD versus SE. As mentioned in the thread already linked by Disruptor, connecting an SE drive to an adapter without DIFFSENS connected fails to downgrade the bus into SE mode, yet the SE drive shorts one side of the differential pairs to ground, this will render the whole bus inoperative. On the other hand, connecting an LVD drive to an adapter like that is likely a gamble as well, as DIFFSENSE on LVD drives is used as input to select the mode (SE fallback vs. LVD). With that input not connected to the bus at all, the drive might or might not work.

EDIT:This comment used to claim that the adapter in this thread does not support differential devices due to a missing DIFFSENS connection. This was wrong. See Re: What scsi card between aha-2940uw and 29160 for details.

I took a look at the photos, and I only see the "standard SCA fanout" style traces that look funnel-shaped. The DIFFSENS connection does not fit the pattern, because it is "inside the funnel" at the 68-pin connector, and "outside the funnel" at the SCA connector. As part of the traces are obscured by the connectors, I just claim it "most likely" does not connect DIFFSENS, but I would be quite surprised if it actually did.

Last edited by mkarcher on 2024-09-02, 21:01. Edited 1 time in total.

Reply 22 of 26, by Nemo1985

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I will gladly do the test but I need to find a suitable hard drive before, apparently the only cheap devices nowadays are SAS 😐

Reply 23 of 26, by ElectroSoldier

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Yeah I know circuit boards too 😉

Long story short for the OP.
Try it and see, it wont damage you drive doing that.

Or I could get really technical and break it down like a cross between Louis Rossmann and Big Clive. But you wouldnt learn anything new if I did. Certainly not about connecting drives to a SCSI controller.

Reply 24 of 26, by mkarcher

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There was a comment (now removed) that mentioned that DIFFSENS is connected on the SCA side. This fact was correct, although the pin numbers mentioned in that comment were strange. So this adapter does not interfere with LVD operation. The pin numbering printed on the PCB for the SCA part does not match common pin numbering at all (which does not impede proper operation of that adapter, though). OP: You can use this adapter with all kind of SCSI devices, except legacy (retroactively called high-voltage) differential devices. High-voltage differential drives are rare, and host controllers supporting high-voltage differential are even more rare. Likely you won't ever encounter them unless you search for them. Don't worry about the high-voltage differential stuff for now.

The attached images show the location of DIFFSENS (purple circles), the trace I missed (red dotted line) and pin numbers matching the usual numbering way for the SCSI connectors.

The attachment SCA-1-marked.jpg is no longer available
The attachment SCA-2-marked.jpg is no longer available

Reply 25 of 26, by ElectroSoldier

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Yeah I deleted the comment because I really dont want the conversation with you.
The pin outs are what they are and can be found in any technical manual for it...
This one for instance
https://www.manualslib.com/manual/54874/Fujit … c.html?page=124

The last thread about SCSI descended into a flexing contest and I really dont see the point in allowing this thread to descend into that. (and the pointless spin off thread that came from it too).
It looks to me like youre trying to make SCSI and its use complicated. Its not. Its a bit more involved than IDE was, sure, but its not complicated at all, and I find the mental flexing pointless in the extreme.

Having looked at the traces the adapter he has will work for what he wants to do.
So I told him to try it out.

There is little or nothing more to be said about it until he does that.

Reply 26 of 26, by maxtherabbit

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Every random ebay SCA adapter I've tried has worked with LVD just fine. Idk maybe I'm just lucky