SCSI controller questions

For my own personal reasons, I decided to get an ISA SCSI-2 card for my Pentium computer. It’s a DTC 3520A. I finally got a couple of SCSI devices and when testing them out, I got the following error message from the onboard BIOS
“Host adapter failed in interrupt channel test”. It’s preset for IRQ 11, but when I tried IRQ 10, I got the same thing.

When I boot into Windows XP, it doesn’t know what driver to use for the SCSI controller. According to a readme file on the installation disk it says that the Windows 95 and NT driver is Adaptec “AHA-1515/AHA150X” but I can’t find a driver that will work with XP. I can’t find that particular driver, and when I chose a more advanced driver from a list XP gave me, it didn’t work.

So, my questions are

  1. What’s the normal cause of an interrupt channel test failure?

  2. I don’t have a hard drive hooked up, just a CD-Writer and a zip drive, is that OK, or does a SCSI controller really prefer a hard driver hooked up?

  3. The SCSI card, is set to 7, of course, the zip drive is set to 5 and the CD-Writter is set to 4. That means that I’d set the termination for the Zip drive, but not the CD-Writer, right?

I know that there’s a million reasons why I shouldn’t have gone with SCSI-2, but I’m comfortable with the choice I made. The only thing I might change is getting a new card if I can’t get Windows to recognize it. Although I don’t know if I should go with another SCSI-2 card (ISA or PCI), or go with a new card, and get an 80 to 50 pin adapter.

Anyway, Thank you in advance.

That DTC card should be driver compatible with the Adaptec AHA-1520 that was a pretty common card once. I can’t remember now if XP has drivers for it though.

  1. ISA cards are pretty stubborn about having their own dedicated IRQ, so you could try to force an IRQ for the card in the system BIOS.

  2. Any device should work, although some older controllers seem to have trouble booting CD-ROMs.

3 & 4) The last device in the chain should be terminated. That means the farthest one from the controller on the cable.

I hope this helps.

I’ll look that up, thanks.

I’ll see if I can do that. The SCSI card lets you choose between IRQs 9, 10, 11, and 12. Well, 12 if off limits if you have a PS/2 mouse. The default is 11, but 10 didn’t work either. I’ll check out the system BIOS to see if I can force an IRQ. Thanks.

Actually, my CD-ROM seems oK, but I don’t noticed any lights going off on my zip drive when the card is scanning the two devices.

So terminating has nothing to do with the device ID?
So since the CD-Writer uses the connector in the middle of the cable, and the zip drive uses the cable at the end of the connector, then the zip drive would be terminated, but not the CD-Writer. OK, thanks.

[quoteI hope this helps.[/QUOTE]

Yes, it does. Thank you.

Some/most MB’s with an ISA slot have place in the BIOS menu where you can force assignment of an IRQ to a particular ISA slot.

SCSI Termination can be a beast. You should terminate the last device on each end of the chain. So if you only have internal devices:


Drive 3 should be terminated.

If you have both internal and external devices:


Then both external 1 and internal 2 should be terminated.

I understand, thanks.

Well, I assigned IRQ 11 to ISA Legacy (it was ISA/PCI PNP) and the controller card works. Now, I just need to see if I can find an XP driver, or else get a new controller card I guess.