Wide-Ultra 68-pin to 50-pin Blues

[raoulduke]

I got this 9.1gb Compaq Wide-Ultra SCSI-3 last August before I got my Powermac 7100 and before I knew anything about SCSI.  I got an adapter which didn't seem to work.  I've tried all combinations of SCSI Term (always jumpered), Term Power, Disable Target Initiated Synchronous/Wide Negotiation, and Disable Unit Attention.  I periodically try Termination Power or Remote Start on the adapter.  I don't usually jumper a bus address since this is the only SCSI device in the machine right now.  I removed the CD drive.

I'm basically at a loss.  This is the first time I've tried to adapt to 50-pin.  I'm using another adapter.  It also doesn't work.  I'm open to any thoughts.

Oh and at the moment it's in an external enclosure.

 

[johnklos]

Are you sure it's not differential? Google the model number and see.

 

[raoulduke]

Truly, I don't know what that means.  Oh and major error on my part - it's ***80-pin***, I apologize.

I googled the P/N (313706-B21), and it's confusing as to who actually manufactured this drive and possibly who slapped their name on it.  In any event, I googled that with "differential" and I can't find any evidence of an overlap.

But as I said, I don't really know what that means.  Low-voltage differential?

 

[johnklos]

Yes. Low voltage differential won't work at all. Certain differential drives (non low voltage) require that they be set to single-ended mode in order to be backwards compatible.

If it's 80 pin SCA, then the adapter can be the reason it doesn't work correctly, although I haven't ever seen any issues with SCA drives because they're required to be backwards compatible.

 

[raoulduke]

Thanks.  There aren't any single-ended mode settings or anything, and I don't think it's differential.

When I turn on the computer - either with the drive in the enclosure (I was using that because of possible termination issues although I don't know that the enclosure has termination; I just suspect it may) or in the machine - it powers on with the machine, starts to spin, then shuts down after what seems like a diagnostic cycle.  That's regardless of the jumper settings.  I had tried experimenting with combinations of those 3 (Target Init, Unit Attn, and Term Power) at the suggestion of Sonic Purity.  I don't know if people here still know him.

Long story short, neither of us could figure it out so I assumed it was the adapter.  When my 2gb 50pin died last week I started fiddling with it again and got another adapter [literally the only two different ones I could find on Amazon].  I'm open to suggestions about adapters but I increasingly have trouble believing that's it.

 

[Unknown_K]

There are LVD/SE and HVD cards and drives (HVD are also called just differential since it was the first standard). Connecting HVD to a mac will cause a drive shutdown or magic smoke.

Anyway a 7100 is a Nubus machine with built in 50 pin SCSI. Unless you have a Nubus SCSI card I will assume you are just using the built in 50 pin connector.

The problem with SCA drives is they have no built in termination so you must terminate them on the cable or on the drive at the end of the cable. On the 7100 the SCSI CDROM should have a termination jumper so you are in luck. Now you need a SCA to 50 pin adapter or a SCA to 68 pin adapter and a 50 to 68 pin converter. The hard drive has to be able to go into SE mode otherwise it will not work.

 

[johnklos]

BTW - what I wrote was a bit vague. LVD will work if it is used with a proper terminator. It won't work at all if it's the kind which doesn't switch to single ended (which is rare). Some HVD have switchable drivers (also rare; talking about bus drivers, not software drivers, BTW), but if the drive doesn't have that option, there's no way it will ever work and may break things (magic smoke escaping is certainly possible).

The simplest configuration is to get an SCA to 50 pin adapter with termination built in, then connect it to the internal bus using the internal cable. The external enclosure and adapters add a lot of variables.

 

[raoulduke]

"Single Ended SCA2 Wide Ultra, SCSI-2/3"

(313706-B21): http://www.comitworld.com/alpha_storage/disk_drives.htm

So I had wondered about termination, because there are no resistors although there are jumpers for SCSI Termination and Termination Power, both of which I've tried jumped and not jumped at this point, etc. etc.

Even with the CD drive in, which I'd had in when originally testing the drive months ago, there's no recognition in SCSI Probe.  The only chain from then to now is the adapter, and it's hard to believe both adapters are defective.

I don't have an internal terminator, so I'll put the drive medially between the bus and a terminated HD.

 

[johnklos]

Not sure I follow. With the CD drive in, NOTHING shows up in SCSI Probe?

What do you mean by both adapters? What's the second adapter?

What are you referring to when you say there are jumpers for SCSI termination and power but no resistors? Do you mean the SCA adapter has jumpers but no resistors?

 

[raoulduke]

Okay several things.  I mislabeled this post.  It's an 80-pin drive.

I bought an adapter in August that was 50-pin, 68-pin and 80-pin.  I last week bought a 68-pin to 50-pin adapter.  Neither have worked.

In SCSI Probe with the CD Drive, only the CD Drive shows up, sorry.

Well actually both the adapter and also the drive itself [have termination power options and lack terminator resistors].  But I meant the drive; the 80-pin Compaq has a SCSI Termination jumper option but lacks the socketed resistors present on all the 50-pin drives I have.

I have a Quantum ProDrive 40S from an SE/30 that doesn't mount or read properly but is terminated properly [as far as I can tell; or should be].  With options [on Compaq]: ID1, ID1 & Disable Target Initiated Synchronous/Wide Negotiation, and ID1 & Termination Power jumpered, only the Quantum shows up.

I'm at a loss.  The options on the drive itself are Termination Power / SCSI Termination / Disable Target Initiated Synchronous/Wide Negotiation / Disable Unit Attention / SCAM / Delayed Start / Disable Auto-Start / and the ID options.

 

[johnklos]

Hmmm... Puzzling. SCA drives aren't supposed to have jumpers at all.

Have you tried using the SCA to 50 pin adapter with the drive on the internal bus with the Quantum at the end of the chain for proper termination?

 

[raoulduke]

Sorry I never saw this.  I'm pretty sure I did, yea.  When i get a 50pin passthrough terminator I'll go through this and several other drives more methodically.

 

[johnklos]

Another thing to do is to have a complete, terminated 68 pin chain with the motherboard as a 50 pin terminated end using an adapter. I have a few Quadras which are configured this way using 68 pin U2W SCSI to IDE adapters (80 MB/sec). The adapters wouldn't negotiate to single ended, narrow unless the bus was terminated wide. You can see my adapters and 68 pin cable and terminators in my Quadra 610 here:

http://www.macbsd.org/~john/quadra610/