TITLE
    Performa 600, Macintosh IIvx: SCSI ID and Termination
Article ID:
Created:
Modified: 		11109
12/11/92
12/11/92
TOPIC



    I have a Performa 600 with the internal AppleCD 300i and an
    external LaserWriter SC.

    1) What is the SCSI ID setting for the internal AppleCD 300i?

    2) How is the internal AppleCD 300i terminated (it already has two
    internal SCSI devices)?

    3) What is the termination procedure for external devices? With a terminator
    on the LaserWriter SC, the system would not start. Without the terminator,
    the system worked. Does this mean that external devices are not the last
    SCSI devices on the chain?

DISCUSSION


    1) The SCSI ID of the internal AppleCD 300i in the Performa 600 and the
    Macintosh IIvx is "3".

    2) The Performa 600 and the Macintosh IIvx provide on-board SCSI termination
    when no external SCSI device is connected to the DB-25 connector. Once an
    external SCSI device is plugged into the SCSI port, you need to add a SCSI
    Terminator on the last device in the external SCSI chain

    SCSI ID has nothing to do with termination or where the device is
    in the SCSI chain. You can have the SCSI ID set to 1 and have it be the
    last device on the chain -- and it will work.

    3) We have seen occasional problems like this when connecting SCSI devices on
    the SCSI bus. SCSI termination seems at times more art than science. The
    basic answer is: If it works, then it's OK to leave it that way. If more
    devices are added to chain, then you will more than likely need to add a
    terminator.

    Other workarounds are:

    * Start up the Macintosh before powering up any SCSI devices.

    * Double-terminate the SCSI bus, using platinum terminators. CAUTION: Do
    not use two black (Macintosh IIfx) terminators, as this may damage the
    SCSI device or logic board.




Document Information
Product Area: Computers
Category: Macintosh Performa 200 through 640 Series
Sub Category: Macintosh Performa 600

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