Adaptec 1510 - SCSI Hard Drive Question

Much as I hate to admit I am using W95 on a Pentium 166 MMX, it is really to run E11 and run RT-11. Included, I have an Iomega SCSI Insider (100 MByte Zip drive) which came with a (wonder of wonders) Adaptec 1510 SCSI host adapter (at least I think that was the Adaptec number - it is inside the guts of the motherboard and I ca pull it to check if absolutely necessary). Now, wonder of wonders, not only does the 1510 and the Iomega APSI device drivers support the Zip drive, but I can also connect the Sony SMO S-501 as well. In fact, at one point, I had 3 of the Sony magneto optical drives (SCSI ID 0,1,2 and the Zip at ID 6) all running on the 1510 and of course recognizing all four SCSI units at boot time (along with a C: drive and an IDE CD-ROM drive) for a total of 8 drives: A: (3.5" floppy) B: (5 1/4" floppy) C:, D:, E:, F:, G: (Zip) and H: (CD-ROM). About half the time I boot without the Sony drives and the ZIP drive and the Iomega device driver complains there are no SCSI IDs, and I just press any character to continue. On occasion, I want to use a SCSI hard drive (currently I have both a ST11200N and a ST32550N) instead of the Sony drives (I hardly ever use the Zip drive - it is normally cabled to the 50-pin cable but not powered on). When that happens, i.e. want to use the Seagate drives, I find it necessary to FIRST boot W95 with the Sony drive powered on at the same SCSI ID I will be using for the Seagate drive. Then I power down all the Sony drives, disconnect them ALL since the Sony drives are external boxes) and power up (sometimes all three) the Seagate drives, i.e. I can't seem to keep both the Seagate drives and the Sony drives powered up on the SCSI cable at the same time. In addition, if I boot W95 with just the Seagate drives powered on, they are not even recognized at all - actually not quite true. Although W95 and the device drivers from Iomega will not allow these Seagate SCSI hard drives, the are "partially" recognized by E11 to the point that I can "MOUNT" them under E11, but I can't really access them properly. It looks as if the Iomega supplied device drivers will not recognize a fixed (i.e. non-removable media hard drive). I would prefer to not use W95, but that is all I have to use when I post to classiccmp and use email and the internet. Plus, I really use the PC to run RT-11 on the PC, so please don't suggest getting a MAC or running Linux or some equally reasonable answer since I like having the system right now with RT-11 and the Zip and Sony drives and I can put up with the problem of having to boot with Sony drives if I have to. So, it sounds like a termination problem on the SCSI bus. But the ST11200N is definitely terminated from the drive. I checked at: http://www.seagate.com/support/disc/scsi/st11200n.html and J2 has both the Parity and Terminator jumpers. But when even just one ST11200N drive is cabled on and powered on by itself, booting W95 does not recognize the ST11200N, but having the Sony drive there first does the job as stated above. So I am starting to think the problem is more likely the device drivers. Could the 1510 and the Adaptec device drivers just not recognize an ST11200N (or any other SCSI hard drive that is not removable), but be fooled once booted with the Sony drive which has a removable media? NOTE: I want to use the ST32550N under both RT-11 as a permanent and much faster hard drive (the Sony is quite slow) and W95 as a backup device - I have an option on a bunch of these drives even if I can't solve the boot problem - does anyone else want a few as well? Question: Can anyone HELP? Does anyone have any experience with the device drivers from Iomega for their Zip drives? If that is the problem, then I am probably stuck since I prefer to keep the Sony and Zip drives over the hard drives. Plus if having to re-cable after I boot with a Sony drive is the answer, then I can probably live with that for a few more years. Thanks in advance for any suggestions! Sincerely yours, Jerome Fine