Savvio SCA drives in a 6500?

[techknight]

Here is an adventure trip for you. 

I have a couple of those 36GB and 72GB savvio drives that everyone is using to replace in their 68Ks. 

Well, I wanted to stick a 36GB in my 6500 as a backup drive from the main IDE drive. Problem. it doesnt like those drives. 

When I was running 8.6, it seemed to be touch and go. it would startup just fine, and see the drive. BUT. every time I would shut down, and start back up, it would freeze at the mouse cursor until I unplugged the drive. 

Also, if I reset pram, and power it on only by the rear power button, it would startup. Odd...

Installed OS9, now it freezes during startup with the drive installed. I have to remove the drive in order for it to boot. 

tried my 72GB drive, and the other 36GB drive, same thing. Very odd. 

Tried a terminated adapter and it made no difference as I figured it would not. I installed the drive in the bay where a zip would normally go, and there is a terminator in the cable. 

Are PPC machines just incompatible with these drives? has anyone else tried it? 

 

[uniserver]

i have one in my 6100 and it works great. 8.6

i have one in my 7500, /w G3 cpu upgrade and it works great, Mac OS 9

 

[techknight]

well its not liking this 6500, and I am not sure why. 

 

[CelGen]

Newer SCA drives dropped support for the older SCSI buses. Some machines simply can't see the drives anymore while others have really hit-and-miss support.

 

[trag]

The nice thing about the Savvio drives, at least the ST973401LC (73.4GB) and the ST936701LC (36.4GB), is that their datasheet specifically says that they support legacy SCSI modes.

Savvio.pdf

 

[techknight]

but I am beginning to wonder if it doesnt support every part of older SCSI modes, because of the freezing in the PM6500. These drives work great in my 68Ks. I didnt try any other powerPC systems, I only have 2 others which is a 6100 and a TAM. 

 

[TheWhiteFalcon]

It's possible they have some kind of weird SCSI implementation that the drive maker didn't consider.

 

[techknight]

its certainly possible. But I was hoping if someone had a 6400/6500 handy with one of these drives, if they could test it to make sure its not just me. 

 

[Trash80toHP_Mini]

WAG: The Savvio's draw a lot of power. If your PSU and MoBo are on the edge of tipping over the edge due to capacitor degradation, adding a Savvio will give it a good hard shove.***

Zips have minimal power requirements. Try removing the ZIP, boot drive and any cards installed and to if that makes a difference when booting from a CD and installing an OS on the Savvio itself.

*** Caution: in need sleep or coffee. YMMV

.

 

[Trash80toHP_Mini]

edit: Had some coffee:

I didn't even notice who asked the question, you've probably checked the power output/requirements. My boards aren't in the original containers, but I have do a 6360 with a 6500 board in it if it's not the original. I can give that a try if nobody beats me to it. I'm off the next couple of days.

 

[uniserver]

I have a 6400, I can try, maybe later today,  in the mien time try it in your 6100, it will work great.

 

[AppleIIGuy]

Does the SCS to  50 pin scsi had have proper termination for the high bits?

http://en.wikipedia.org/wiki/Parallel_SCSI#Mixing_Wide_and_Narrow

Both narrow and wide SCSI devices can be attached to the same parallel bus. All the narrow SCSI devices must be placed at one end and all the wide SCSI devices at the other end. The high half of the bus needs to be terminated in between because the high half of the bus ends with the last wide SCSI device.

https://www.datastoragecables.com/scsi/scaadapters/SM-031.html SCA adapter with proper termination must be last device on scsi cable

 

[techknight]

Yea, I dont think so. the ebay adapters have NO termination, and max1zzz adapter only has half-ass termination. 

 

[max1zzz]

Whats so half ass about the termination on my adapters?

 

[Trash80toHP_Mini]

I'm wondering about the Zip drive on those boxex. ISTR something cutious about its position on the internal chain, possibly having to do with termination?

@ max: I was going to ask the same thing, but forgot. I've got some of the OWC(?) terminators for comparison. Have yours got all 16 resistors?

 

[techknight]

the D8 through D15 doesnt appear to be terminated. Just D0 through D7 which is used in small narrow SCSI. 

 

[techknight]

I see the resistors for the 8 signals, and the 8 data bits. But I see 4 more on each side. Not sure what those are for. 

 

[AppleIIGuy]

SCA is 16 bits wide so you only need to terminate 8 pins to make it narrow

 

[Trash80toHP_Mini]

Pics I've collected:





I didn't find a pic of my OWC Adapter, but it has three removable Resistor Packs (8pin) to control termination for its 50pin connector. It doesn't have the internal Wide SCSI connector as in the top pic, so one resistor pack (the only 10pin pack) is soldered to the PCB. This would be the "neck-down" termination converting SCA to the Narrow 50pin SCSI Bus.

If Max revises his adapter to include this resistor pack, that'd be the other AssCheek, or so I would surmise.

edit: I'm curious as to the considerable number of extra resistors. Would that be for addressing and control lines overlapping the two termination configurations?

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