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SCSI Drive Hookup and OS install for Q950

SirFoxx

SirFoxx

macrumors regular
Original poster
Jul 9, 2012
137
2
Galien, Michigan
Right before I left for college, I asked about how to get an 18gb SCSI drive to work with my Quadra 950. I managed to get it formatted for HFS using my beige G3 (using an adapter for hookup going from the newer cable with the active terminator to the old style cable) and that is as far as I got. When I hooked it up to my 950, in Mt. Everything the most I got out of it was it saying "Termination Error!" I do have the termination block on the cable, but I'm not sure what else to do.

Also, for when I managed to get the drive recognizable by my Q950, do I need to use the patched installer or..? I've been having a hard time finding a good patched installer as FTP servers and other links have been dying on the internet. I have tried using the A/UX installer, but it bombs every time.

Which jumpers need to be jumped, and what installer files do I need to use? I've struggled with this for around a year with no luck :/

IMG_20150521_013647_zpsfgskyouc.jpg

IMG_20150521_013717_zpshkv5zbf5.jpg
 
I'm going to suggest leaving the jumpers as they are, which makes the drive SCSI ID zero. Make sure you have no other SCSI devices on the same ID or change it to another ID.

Note preferred (but not essential) is -

boot drive ID = 0
CDROM ID = 3
2nd drive ID = 1 thru 2 and 4 thru 6

I would try using a three headed older 50 pin cable. Place the drive on the middle connector, the old terminator at one end, and plug the other end into the motherboard.
 
keysersoze said:
According to LEM, on the Q950:

"The internal SCSI bus is terminated on the motherboard, so internal SCSI devices should not be terminated. This is the opposite of all other Macs except the Quadra 900."

http://lowendmac.com/1992/quadra-950/
Click to expand...

Well, well. You learn something new every day.

The Developer Technote for the 900 (to be read inconjunction with the 950 dev note) does say:

In the Macintosh Quadra 900 computer, the SCSI bus is divided into internal and external buses, each controlled by its own IC. Both ICs are NCR 53C96 devices.

The internal and external SCSI buses are logically connected but electrically separate. The external bus is electrically isolated from the internal bus so that changes in external cabling and termination have no effect on the performance of the internal SCSI devices.

The cabling and termination of the internal SCSI bus are optimized so that the 53C96 that controls the internal bus can support data transfers at a faster rate—up to 5 MB/sec. Because the external cabling and termination are less predictable, the 53C96 that controls the external SCSI bus may run more slowly than the 53C96 that controls the internal SCSI bus...

The Macintosh Quadra 900 includes two internal 50-pin SCSI connectors and one external DB-25 SCSI connector...

♦Note:
SCSI devices designed for external use should be terminated
if they are the last device on the chain. SCSI devices designed for
internal use should not be terminated.
Click to expand...

I don't know why I didn't know this. I used to run one as a server with several internal hard drives. SCSI voodoo probably made it work. :rolleyes:


LATE EDIT:
Looking deeper into this, it appears that Apple's advice stems from the fact that the internal SCSI cable has a terminator fitted to the end. This being the case, my original advice still stands. The only other thing to look out for is to NOT have conflicting SCSI IDs across the internal and external SCSI connectors if you ever intend to run system 7.0 or 7.1 on the Q950.

Also, ensure you're using the internal SCSI connector. There are two 50 pin SCSI connectors on the motherboard. The one near the PDS slots is the internal connector.
 
Last edited:
I'm going to be updating this post when I try different things. With just an adapter plug on the HDD using just the 50 pin cable in the slot near the PDS slot, it would not show up. (The hdd is 68 pin and I don't have any other SCSI devices plugged in.

On a side note, whenever I shut down my Q950, I have to reformat and make a new bootup disk...It'll show the happy mac, then eject the disk and reboot. Don't know if it some problem with my Q950 or the image I am using to make the disk.

EDIT 1: I have the 68-pin cable, with the 68-pin terminator on the end, plugged into the adapter block, and that goes to the 50-pin cable without the 50-pin terminator block, and in Mt Everything on ID 4 it says "ERROR -- Check Termination!!!" I have position A of the 50 pin plugged into the block, and the 68-pin, where it normally plugs into a motherboard, plugged into the adapter block, and then the HDD is plugged into position A on the 68-pin cable...I hope this makes sense
IMG_20150521_163430_zpslmj4xchx.jpg
 
Last edited:
MacTech68 said:
How are you setting the SCSI ID to 4 ?

Also, with the current setup, try the drive on the connector closest to the 68pin terminator.
Click to expand...

Thats the thing, I didn't. None of the ID jumper blocks on the HDD and the adapter block are selected. When I moved the hard drive to the new spot on the cable it will not show up.
 
SirFoxx said:
Thats the thing, I didn't. None of the ID jumper blocks on the HDD and the adapter block are selected. When I moved the hard drive to the new spot on the cable it will not show up.
Click to expand...

Well, that's weird. :eek:

I'm still going to suggest ditching the 68PIN cable, and hooking up with the 50Pin cable only, with the old terminator on the end of the cable.

Does the adapter board fit onto the drive directly, allowing room to plug the 50Pin cable into the adapter board?
 
The 50/68/80 adapter board does not fit on the hard drive, but I do have an adapter that will plug into the hard drive directly.
IMG_20150521_190922_zpsfr506qpp.jpg
 
MacTech68 said:
Woot - let's do that! ;)
Click to expand...

Any specific spot on the cable I should try? In one of my earlier posts today I tried it and it would not show up at all. I seem to recall I had a similar problem trying to get my G3 to recognize it and I think it was due to it not using the correct terminal block, hence why I bought the second adapter (50/68/80) so I could use the 68pin cable. If you want me to try a specific spot on the cable I will go ahead and try again.
 
SirFoxx said:
Any specific spot on the cable I should try? In one of my earlier posts today I tried it and it would not show up at all. I seem to recall I had a similar problem trying to get my G3 to recognize it and I think it was due to it not using the correct terminal block, hence why I bought the second adapter (50/68/80) so I could use the 68pin cable. If you want me to try a specific spot on the cable I will go ahead and try again.
Click to expand...

Try the terminator on the end of the cable and the drive on all other connectors. See what difference it makes (if any) changing the drive's position on the cable.

If you get to see something on SCSI ID zero, then we're half-way there.

The only thing that might help is a 50 Pin active terminator.

Also, regarding the floppy disk - don't manually eject the disk before restart or shut-down. Allow the Mac to handle the floppy disk on restart or shutdown.
 
MacTech68 said:
Try the terminator on the end of the cable and the drive on all other connectors. See what difference it makes (if any) changing the drive's position on the cable.

If you get to see something on SCSI ID zero, then we're half-way there.

The only thing that might help is a 50 Pin active terminator.

Also, regarding the floppy disk - don't manually eject the disk before restart or shut-down. Allow the Mac to handle the floppy disk on restart or shutdown.
Click to expand...

I don't manually eject the floppy when it turns off as the auto eject does it for me. When I put the image back on the disk and turn it on, it will go to the happy mac, restart, then it will boot. However, if you shut it down after it being turned on, it will not boot off the disk until I reflash it.

As for the HDD I will get back to you once I test the different positions on the cable. I will also look for an active 50-pin terminator to buy. Even if that isn't the problem, it'd be nice to have around in case I get another old computer that uses SCSI.
 
SirFoxx said:
I don't manually eject the floppy when it turns off as the auto eject does it for me. When I put the image back on the disk and turn it on, it will go to the happy mac, restart, then it will boot. However, if you shut it down after it being turned on, it will not boot off the disk until I reflash it.

As for the HDD I will get back to you once I test the different positions on the cable. I will also look for an active 50-pin terminator to buy. Even if that isn't the problem, it'd be nice to have around in case I get another old computer that uses SCSI.
Click to expand...

No probs. :)
 
It did not come up on any of the different cable positions, so I will wait for my active terminator to arrive in the mail and report back.
 
Got the 50-pin active terminator in the mail today, and still no luck. I also tried the adapter block and had both active terminators plugged in and it still didn't show up. Any ideas?
 
I do, give me a few minutes. If worse comes to worse, would an 80pin drive work with something this old? I've got a few old server drives laying around as well.
 
I plugged in a 50-pin drive from an old performa I have and it gave me the same check termination I got before with my 68-pin drive on ID 4 (just using the passive terminator). Do you think something failed on the host controller chip? Should I try the secondary external SCSI plug the motherboard has? Or should I try another cable?
 
Yes, it might be worthwhile trying the second scsi interface (since it's a different controller).

I'm wondering if the 'Term Power' on the internal BUS might be bad/faulty.

If that doesn't work try another 50pin cable.
 
Remembering my SCSI days, I had a system that would not work if I used any adapters. I ended up dropping in an adapter that supported both 80 and 68 pin connectors and it worked fine connecting the devices with their proper connectors.

Try setting an address too?

Sometimes I miss SCSI, and, well, then I remember some of the 'fun' we had.
 
MacTech68 said:
Yes, it might be worthwhile trying the second scsi interface (since it's a different controller).

I'm wondering if the 'Term Power' on the internal BUS might be bad/faulty.

If that doesn't work try another 50pin cable.
Click to expand...

So I tried another drive, along with another cable, and in the other slot, and still the same problem (Check term on ID 4). Could it be possible that my power supply is dying? I noticed that my mouse was being a bit flaky with the clicker, but that could just be the mouse. I did have a peek inside of the power supply and didnt see anything blatantly obvious that could be the problem. Any idea where to turn from here?
 
You'll probably at least want to check the termination power.

Though first, I'd re-check the drive in another machine.

Using the pic below, check pin 26 (marked) on the 50 pin connector to ground. This should be +5volts.

Check it with and without a drive connected and with and without a terminator on the end of the cable.
 

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MacTech68 said:
You'll probably at least want to check the termination power.

Though first, I'd re-check the drive in another machine.

Using the pic below, check pin 26 (marked) on the 50 pin connector to ground. This should be +5volts.

Check it with and without a drive connected and with and without a terminator on the end of the cable.
Click to expand...

I tried one of the HDD's from I think a performa (something with a 68k) on my g3 and this is what showed, which means it works.

Now, when plug into the Q950, I get nothing. Voltages w/o the term is ~2mv, and with the term its a solid 4.71v.

IMG_20150527_041703_zpsjm0efg6u.jpg
 
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