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  • SCSI?

    I have a problem that I think you guys can explain to me.

    I have a Tekram DC390F SCSI adapter. To that I have attached an IBM Ultrastar 2ES and a Yamaha CD-RW. I can´t seem to get these two devices to work well together. One drive at the time is no problem, but when I have connected both of them and tries to start the CD-R program the computer hangs hard. The same happens when I tries to open "My computer". The harddrive is attached to the 68 pin port, and the CD-R to the 50 pin port. I have learnt, and also read in the manual, that if you connect like this, you are to terminate both ends of the SCSI channel. So I terminate both the harddrive, and the CD-R as described in their manuals. And still the problem presists. Now.. When I tried installing the CD-R in an friends external case, and used an Active terminator on it, everything worked like it should. Why is this? Is not the standard termination built into the CD-R enough? I am confused here. The 50 pin bus is only 8 bits wide, but the 68 pin bus is 16 bits wide. Has this something to do with it. And how do I arrange my devices so that I have two "wide" devices in the ends of the chain, when I only have a "wide" and a "narrow" device.

    I hope you understand my strange question, and perhaps has an answer to it!

    Thanks
    Vertical

  • #2
    I'm not familiar with that SCSI card, but from your description it sounds like it's a single channel, ie. the HD and CDR are both on the same chain with the SCSI card in the middle.

    Most SCSI cards will themselves have some sort of termination settings, either in software or by physically attaching resistor blocks or dip switches. Try manually selecting this to either no termination, or preferable, terminating just the high bits (the 8bits that aren't present on the narrow cable).

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    • #3
      Hello


      thanks for the reply.
      It is a card based on SymbiosLogic 53C875 chip. The card is in the middle, and from what I can read in the manual it shuld have active terminators, and the BIOS would not let me set these parameters. So I am left with no luck here or what? Because if I am not totally wrong you can not hook up a "wide" unit to the "narrow" part of the chain right?

      //Vertical

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      • #4
        Here's a possible work-around. Get a 50-68 pin converter, forget about the 8bit channel and stick the CD-R onto the wide channel. Terminate the card, and whichever device is at the end of the chain, and don't terminate the middle one.
        I bet you'll have more luck with that.
        Keep the IDs below 8 too as you're gonna confuse things if not.

        ------------------
        Cheers,
        Steve

        PS: Some or all of the above message may be wrong, or, just as likely, correct. Depends on what mood I'm in. And what you know. ;¬)


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        • #5
          I think I have solved it!!

          The external and internal 68 pin connectors are 16 bit wide and is the main SCSI channel. The internal 50 pin connector is mearly the lower 8 bits of that channel. This means that the two internal connectors are parallell. So if you are using one internal wide and one internal narrow device then you only have to terminate the wide device, which also terminates the lower 8 bits for the narrow device.

          Thanks for your help!

          // Vertical


          [This message has been edited by Vertical (edited 09-26-1999).]

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