[comp.sys.atari.st.tech] Trouble hooking up second SCSI device

steve@thelake.mn.org (Steve Yelvington) (08/01/90)

I've been using my homebrew hard drive for a year or so with no
difficulties. Recently I bought a (used) Seagate 138N. I recabled
my system, running a 50-line ribbon from my Supra host adaptor
to the Seagate (where I tapped the line) to my Adaptec, which controls
an ancient Wren I.

The Adaptec is configured as SCSI 1 (and has been all along).
The Seagate is configured as SCSI 0.

Now comes my problem.

I can't use both drives. I can use one or the other with no difficulty.
But if both controllers are powered up, only SCSI 0 works.

Oddly enough, I can park and unpark both drives. I just can't interact
with the Wren if the Seagate is on-line. The Seagate is C-D-E; I should
be able to use the Wren as F-G-H-I if Supra's tech people are right.
But those devices do not exist, so far as TOS is concerned.

(I do have Supra's boot software installed on both drives.)

Supra tech support said I should remove the SCSI terminators from both
controllers -- but I find no terminators on either. The Seagate has 10
long pins pointing rearward next to the ribbon connector. The pins are
naked. The Adaptec has nothing at all near the ribbon connector. It has
16 naked pins next to the ST-506 control cable, but I assume they
are for connecting a second ST-506 drive.

Is there something I'm missing here? Would it help to reconfigure the 
Adaptec to 0 and the Seagate to 1? (How do I do that?)

-- 
   Steve Yelvington at the (rain-replenished) lake in Minnesota
   steve@thelake.mn.org

chad@norge.enet.dec.com (Chad Leigh) (08/01/90)

The adaptek has its terminators as (probably) socketed resister packs
(single line).
The Atari OEM Adaptek board that I saw had soldered resistors.  I'd
remove the terminators from the Seagate and put it first in line leaving
the Adaptek last.


Chad

chad@norge.enet.dec.com
Vi elsker dette landet!
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DEC has its opinions, I have mine.
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