Mixing 68 pin and 50 pin drives on 2940uw

[imix4you]

What is the correct procedure for using both 68 and 50 pin drives on 2940uw bus? And what if the 68 pin drives are in 50 pin enclosures? Do I need special adaptors or internal termination on the 68 pin drives? Also, should I flash to firmware v. 4.1.1 from 3.0? I did this an have to use their v.4.0 control panel(?) which has fewer controls than version 3.0. This problem has downed my PT/24 system for two days. Help!

Lee

[Disco_Doctor]

Steve, is there any adverse effects on the performance of the wide buss on the 2940 if you have narrow drives hooked up to the internal narrow SCSI connector while drives are also connected to the external wide SCSI connector.

I'm wondering if imix4you was referring to hooking his drives up in this kind of configuration that I'm talking about...

Thanks!



PS - by the way, I've been using that 4.1 firmware for months now, with no problems at all - and my ultra wide SCSI buss length is probably pretty long if you consider the length of the internal ribbon cable that connects to eight fast/wide Quantum drives plus the 3 foot cable from the Mac to the drive bay...I really don't see the problem with not turning "ultra" off.

[This message has been edited by Disco_Doctor (edited 04-22-99).]

[Steve Rosenthal]

How can I tell if a drive has internal conversion from 68 to 50 aside from the connector. Is there a jumper that lets the
2940 know it (the drive) is a 68 pin operating as a 50 pin.

I think I'm seeing some possible confusion here, so just in case, are you talking about a raw drive, or a drive in an enclosure? If you're talking about a raw drive, then there is no conversion taking place. The drive is either wide or narrow. If you are talking about a wide drive in a narrow enclosure, then the only ways you can tell if it's wide are by either opening the enclosure and looking for a wide to narrow adapter, or by using a utility like Hard Disk Toolkit to check the model number. If it's wide drive, it will usually have a "W" at the end of its model number -- even if it's been adapted to a narrow connector.

Some drives have a jumper that will disable wide negotiation, but it's usually not necessary to use it.

There really isn't anything you need to do to tell the Adaptec card that the drive is wide or narrow -- the drive and card figure it out when the first talk to each other when you boot the system.

I can't flash back to 3.0. My card is a PC version and wouldn't accept 3.0. I guess I have to bite the bullet and buy a mac version (at $50 bucks more, the bastards!)

Ah! Yes, it's true. The Adaptec cards, unlike the ATTO cards, are not cross platform. There are different ROMs for PC cards and Mac cards. They are not interchangeable. For the record, the Mac versions are know as "PowerDomain" cards.

--Steve Rosenthal, Digidesign ETS

[imix4you]

I was talking about the enclosures. Let me back-up and discuss my problem. My G3 wasn't booting when I had 50 and 68 pin drives on the accelerated bus. I reversed the positioning of the drives and still couldn't boot. I was able to boot with one drive attached to the 2940 but not more. Hence my question about internal (to the enclosure) 68 to 50 adaptors. Do they have a special look or have jumpers to terminate the high byte? Or do drive manufacturers have unique solutions.

Hope this wasn't too confusing...

Lee

[Steve Rosenthal]

Hi Lee,

My G3 wasn't booting when I had 50 and 68 pin drives on the accelerated bus. I reversed the positioning of the drives and still couldn't boot. I was able to boot with one drive attached to the 2940 but not more. Hence my question about internal (to the enclosure) 68 to 50 adaptors. Do they have a special look or have jumpers to terminate the high byte? Or do drive manufacturers have unique solutions.

Okay, I think I have an answer for you. Let me recap to make sure I've got the facts straight:

You've got a G3 with a SCSI card -- I'm assuming it's the OEM SCSI card. In other words, you bought your Mac with the SCSI configuration option. (Correct me if I'm wrong, because my whole theory hinges on this point.)

You can't attach more than one external drive to the SCSI card without making your system unbootable.

If those facts are correct, then here's your problem, as far as I can tell:

Apple does not support the use of the external SCSI port on the SCSI configured G3s (Beige or Blue and White). The internal cabling for the boot drive runs to almost three feet. This is very near the limit that single-ended Ultra SCSI can support before it gets very flaky.

With two additional drives added to the SCSI bus -- remember, this is a single-channel card, so it's all the same bus -- you are most likely in excess of the cable length limit.

Unfortunately, at this time, there is no way to control the SCSI bus parameters of the OEM SCSI cards, so you can't reduce the bus speed which will allow longer cable runs.

If I am wrong about your configuration correct me, because that means there might be a solution. (Actually, if you can reply with detailed system information, it'll save some time.)

As for your second question, the 68-pin to 50-pin adapters look like a small printed circuit board with a male 68-pin connector on one side, and a male 50-pin IDC connector on the other. The active termination of the high byte is built into the adapter.

I hope we can zero in on the problem and find a solution.

--Steve Rosenthal, Digidesign ETS

[imix4you]

I solved my problem by spending the money and buying the correct 2940uw card. I read the manual and used v3.0 control to set the card correctly. Works like a champ! I can get 24 playback tracks from PT24 w/o a problem.

Lee

[Steve Rosenthal]

Lee,

Excellent news! Happy tracking!

--Steve Rosenthal, Digidesign ETS

[imix4you]

Steve,

Thanks for the info. How can I tell if a drive has internal conversion from 68 to 50 aside from the connector. Is there a jumper that lets the 2940 know it (the drive) is a 68 pin operating as a 50 pin. I can't flash back to 3.0. My card is a PC version and wouldn't accept 3.0. I guess I have to bite the bullet and buy a mac version (at $50 bucks more, the bastards!)
Lee