Connecting Your Zip Drive to a SCSI Chain
Checking SCSI IDs on Mac | Checking SCSI IDs on PC
Set the SCSI ID on your Zip Drive | Set the Termination in the SCSI Chain
Locate the Necessary SCSI Cable or Converter | SCSI Cards for Zip Drive
Ultra SCSI Performance | Non-Iomega SCSI Cards


SCSI Guidelines

Connecting Your Zip Drive to a SCSI Chain

SCSI (pronounced SKUH-zee) is an acronym for the Small Computer System Interface—an industry standard for connecting peripherals to most personal computers. The SCSI interface allows you to connect a series of devices to a single SCSI connection by cabling them one to another, forming a SCSI chain. Defined here in the "SCSI Guidelines" is how to connect more than one SCSI device to the same SCSI connection (either built-in or from a SCSI card). A SCSI card is the device that plugs into your motherboard and to which SCSI devices are connected.

SCSI Chain

A SCSI chain is a series of SCSI devices, both internal and external, cabled together on a single SCSI connection. For a SCSI chain using Ultra SCSI, it is recommended that the total length of all cables in the SCSI chain both internal and external should not exceed 1.5 meters (~5 feet).

CAUTION! To avoid damage to your hardware, always turn off power to all devices in the SCSI chain before making any change to the SCSI configuration.


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  1. Before installing your Zip drive, check the SCSI IDs of your existing devices.

    2. The SCSI ID is an address number, ranging from 0 to 7, which is assigned to each SCSI device. Each device in a SCSI chain must have a different SCSI ID number and ID 7 should not be used for any device. It is usually reserved for use by the SCSI host adapter card. The following is an illustration of how a SCSI chain may be configured. Your configuration may be different.

    1. SCSI ID 3
    2. SCSI ID 2
    3. SCSI ID 4
    4. SCSI ID 5
    5. SCSI ID 7 (SCSI Card; The adapter card is usually a device in the chain)

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    NOTE: Each device in the SCSI chain must have a different SCSI ID.

    You can usually check the SCSI ID on the device itself. It is normally the number setting on the back of the drive. A Zip drive is typically set at the factory to SCSI ID 5. Refer to the information that came with that drive for instructions on setting the SCSI ID.

    If you are not able to see the SCSI ID assigned to each of the devices in the chain externally, you may be able to use these steps to find them on your computer:

    Mac® Computers

    If you have Mac® OS 7.6 or higher, you can use the Apple® System Profiler to check the IDs of the devices in the SCSI chain.

    1. Go to the Apple® Menu and select the Apple System Profiler.

    2. Depending on your version of Apple® System Profiler (see the illustrations below, as a example), you will need to either select Device Information under the Select menu, or click on the Devices and Volumes tab.



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      NOTE: If Apple® System Profiler lists more than one SCSI bus, you will need to select the correct one for your Zip drive. SCSI bus 0 is generally the internal (hard drive's) SCSI bus, and SCSI bus 1 is the external. If you are connecting to a SCSI card such as the Zip SCSI card, it may appear as a bus number other than 0 or 1.

    3. If there is another device on SCSI ID 5, you will need to change the SCSI ID of your Zip drive. See step 2 below for instructions on changing the SCSI ID of your Zip drive. If you do not need to change the SCSI ID, continue with step 3 below.

      CAUTION! If you change the SCSI ID of another device in the SCSI chain, do not set it to 0 or 7. The SCSI controller card and the internal hard disk use SCSI ID numbers, by default they are set at 0 or 7.


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    Windows® 95/98/Me PC Compatible Computers

    You can use the Device Manager to check the IDs of the devices in the SCSI chain.

    1. Start your computer.

    2. Go to the Start menu. Select Settings and then Control Panel.

    3. Double click on System, and then click on Device Manager.

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    4. Double click on Disk Drives in the list of devices shown.

    5. Click on the first SCSI drive shown under Disk Drives to highlight it, and then select Properties.

    6. Select the Settings tab and note the Target ID. This Target ID is the SCSI ID that the device is using. If there is no Target ID, it is not a SCSI device.

      7.  



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      • Close the current window for the first drive and repeat steps E and F for the remaining drives under Disk Drives. Once you have completed this for all of the drives, locate any other SCSI devices in the device manager and repeat steps E and F for each device.

        NOTE: To locate the SCSI ID for other SCSI devices, refer to the manufacturer's documentation.

      • If there is another device on SCSI ID 5, you will need to change the SCSI ID of your Zip drive. See step 2 below for instructions on changing the SCSI ID of your Zip drive. If you do not need to change the SCSI ID, continue with step 3 below.

  2. Set the SCSI ID on your Zip drive.

    3. If another device in the SCSI chain is using SCSI ID 5, you can change the ID on your Zip drive using the following procedure:

    • Verify that the power to your Zip drive is off.

    • Set the SCSI ID to 6 by moving the SCSI ID switch on the back of the Zip drive to the up position.

      • NOTE: The Zip drive has only two possible SCSI IDs: 5 or 6. If another SCSI device is using SCSI ID 6, you must change the device SCSI ID to another setting.


    1. SCSI ID Switch: upper position is 6; lower position is 5

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  3. Set the termination in your SCSI chain.


    4.

    SCSI termination is the method in which data is sent through a SCSI chain. The data signal is constantly sent from one termination point in the SCSI chain to the other. If one side is not terminated properly, or too many devices are terminated, the SCSI chain may not work correctly.

    NOTE: SCSI guidelines require that the two ends of the SCSI chain have termination ON. Make sure also that the devices in between the two ends are NOT terminated. The SCSI adapter, or SCSI card, is also considered a device.


    1. Last drive in internal SCSI chain is terminated.
    2. Middle chain is not terminated.
    3. Middle chain is not terminated.
    4. Last drive in external SCSI chain is terminated.
    5. SCSI adapter is not terminated.

    CAUTION! Data loss can occur if SCSI termination is not set properly.

    If your Zip 250 SCSI is the last device on the chain, set the termination switch in the upper or ON position.


    1. SCSI termination switch (1=ON; 0=OFF)

    Other devices may have switches similar to the Zip drive or may use a termination block similar to the one shown below. Refer to the documentation that came with that drive for information on proper termination.



    1. Termination block

  4. Locate the necessary SCSI cable or converter.

    5. You will need a different cable or a cable converter if you are connecting the Zip drive to a device that does not have 25 pin D-Sub connector. To purchase Zip cables, converters and accessories, see Purchasing Iomega Products. The illustrated chart below shows some of the common types of SCSI connectors. If the device that you are connecting to has a:

    25 Pin D Sub Connector—The SCSI Zip drive and the Zip Zoom SCSI card use this connector. This connector works directly with the Zip SCSI data cable or any standard 25 pin SCSI cable. If you need an extra Zip SCSI data cable, see Purchasing Iomega Products.

    50 Pin High Density Connector—Iomega Jaz® drives and Jaz Jet SCSI adapters use this connector. Use a 50HD to 25 D-sub SCSI cable to connect your Zip drive. To purchase this cable, see Purchasing Iomega Products.

    		50 Pin Centronix Connector—Some older SCSI adapter cards and drives use this connector. To connect your Zip drive to this connector, use a 25 pin D Sub SCSI female to a 50 pin Centronix male cable converter with a Zip data cable. To purchase a Zip 25-50 pin cable converter, see Purchasing Iomega Products.


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    CAUTION Always make sure you connect your Zip 250 SCSI drive to a SCSI connector and not to a parallel port (printer port). The Zip SCSI cable fits on the parallel port, but the Zip SCSI drive will not work on a parallel port. If you connect the Zip SCSI drive directly to a parallel port, it may damage the drive or the computer.

  5. Connect the SCSI cable from the Zip drive to your existing SCSI chain.

    Connect the cable coming from the left SCSI port in the back of the Zip drive to the computer or to the previous SCSI device in the SCSI chain. If you are connecting another device to the Zip drive, follow the cable from this device and connect it to the right port on your Zip drive. You may need an adapter to fit the 25 Pin D-Sub connector on the Zip drive.

    CAUTION! When connecting the Zip drive with other SCSI drives make sure the SCSI ID and termination on your Zip drive are set correctly.


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    SCSI Cards for Zip Drive

    Your Zip drive is a high performance drive that will work with most PC/Mac® SCSI cards (i.e. Zip Zoom PCI SCSI card or Mac standard built-in SCSI connection). The typical data transfer speed is 10MB per second.

    Ultra SCSI Performance

    Ultra is a Fast SCSI-3 specification capable of 20MB per second transfers. If you choose to install a PCI Ultra SCSI card instead of a Mac standard or a Zip Zoom card, you must connect your Zip drive at the end of the chain. The Zip drive does not operate at Fast SCSI or Ultra SCSI speeds but it should not slow the performance of other devices if it is connected at the end of the chain.

    For example, if you want to connect a Jaz 2GB external drive and a Zip 250 SCSI in a SCSI chain, configure the adapter BIOS so that the Zip 250 is set to non-Ultra SCSI performance (10 MB per second). Then turn off your computer, connect the Jaz drive in the SCSI chain, connect the Zip drive, set SCSI termination, and reboot.

    NOTE: When connecting your Zip drive to an Ultra SCSI chain, you must use only shorter, premium-quality data cables for all drives connected. It is recommended that the total length of all cables in the SCSI chain both internal and external should not exceed 1.5 meters (~5 feet).


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    Non-Iomega SCSI Cards

    If you are using a non-Iomega SCSI card to connect your Zip drive on a PC, the card must have a compatible 32-bit miniport driver for Windows® 95/98. If you are not sure that your card is 100 percent compatible, check with the dealer where you purchased the card or the card manufacturer. You can also check the Iomega Web site for information on compatible cards for the Zip drive. Go to the Iomega web site at http://www.iomega.com:

    1. Click Support.

    2. Go to the Ask Iomega section at the bottom of the page and type compatible SCSI cards and click the Ask button.

    3. A query of questions will be loaded. Click the Ask button next to the question that asks what SCSI adapters and/or cards are compatible with your drive.

    Make sure the necessary software for the adapter is correctly installed on your system before installing the Zip drive.


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