Your Dual Channel Ultra2 LVD SCSI card (version 2) is a peripheral component interconnect (PCI) card that allows you to connect devices that use the Small Computer System Interface (SCSI). You can connect internal or external SCSI devices such as disk drives, CD-ROM drives, scanners, and other devices. A SCSI port permits high-speed communication between the computer and the device.
You connect internal and external SCSI devices to the card using SCSI cables. Your card also comes with a 68-pin VHDCI to 68-pin connector cable for connecting 68-pin devices. You can purchase SCSI cables from an Apple-authorized dealer or retailer.
Advantages of Your Dual Channel Ultra2 LVD SCSI Card
Your Dual Channel Ultra2 LVD SCSI card has two data channels and uses Low Voltage Differential (LVD) technology.
This technology provides the following benefits:
- High data transfer rates: Your card can transfer information over a single channel at up to 80 megabytes (MB) per second, twice as fast as Ultra SCSI devices.
- Connect more devices: You can connect up to a total of 30 SCSI devices to the card (15 per channel) internally and externally (limited by the type of devices and the number of internal devices your computer is designed to hold).
- Use of longer cable lengths: The cables used to connect a chain of Ultra2 SCSI devices can be up to 12 meters (about 39 feet) long facilitating easy positioning of external devices.
- Compatible with older SCSI devices: You can connect other SCSI devices that are not as fast as the Ultra2 SCSI, such as Wide Ultra, Narrow Ultra, Fast, and standard SCSI devices.
Note: Older SCSI devices must use SCSI Manager 4.3-compliant drivers. To determine if your device works with SCSI Manager 4.3, see your SCSI device documentation.
Connecting SCSI Storage Devices
You can connect SCSI devices in a chain. The first device connects to one of the SCSI card's connectors, the next device connects to the first SCSI device, and so on.
The card has an external cable connector for external SCSI devices and an internal connector for internal devices.
Channel 1 serves the 68-pin VHDCI external cable connector. Channel 2 serves the 68-pin internal connector.
All devices connected to the channel 1 connector are part of a single SCSI chain. Likewise, all devices connected to the channel 2 connector are part of another SCSI chain. You can connect up to 15 total devices to each channel for a total of 30 devices (although your computer will not be able to house this many devices internally.)
About Channel Data Transfer Rates
The SCSI card transfers information in Ultra2-LVD mode or single-ended mode.
In Ultra2-LVD mode, a chain of Ultra2 SCSI devices can transfer data at their fastest speed, 80 MB per second. However, if you connect a slower SCSI device to the chain, the channel defaults automatically to the slower single-ended mode.
In single-ended mode, a channel can support different data transfer rates from each device up to a top rate of 40 MB per second. For example, if you connect SCSI devices that have different transfer rates, each device transfers data at its own speed without affecting the transfer rate of other devices on the channel.
When you plan your chain of SCSI devices, take into account whether you want the chain to operate in Ultra2-LVD mode or single-ended mode. One channel can operate in Ultra2-LVD mode while the other operates in single-ended more. When connecting different SCSI devices to a channel that will operate in single-ended mode, connect Wide devices first (closest to the connector) followed by Narrow devices.
Make Sure Each Device In a Chain Has a Unique ID Number
Each SCSI device in a chain connected to your card must have its own unique ID number from 0 to 15 per channel. You can assign IDs from 0-6 and 8-15 to Wide SCSI devices. You can assign Narrow SCSI devices IDs from 0- 6. (The number 7 is assigned to the card.) The SCSI ID number helps the computer keep track of the devices when several devices in the SCSI chain are communicating with the computer simultaneously.
The SCSI devices can be in any physical order in the chain; it is not necessary to arrange them in numerical order. See the instructions that came with each SCSI device for information on checking and setting its SCSI ID number.
Important If two or more devices in a chain have the same ID number, your computer may not start up properly, your equipment may malfunction, and you may lose data as a result.
Use the Right Type and Length of Cable
To attach an external SCSI device to your computer or to another external device, always use SCSI cables that are double-shielded, such as Apple SCSI cables. Never use printer-type RS-232 cables. Poor-quality SCSI cables are often the cause of SCSI problems. Avoid mixing brands and types of SCSI cables.
Keep the cables between SCSI devices as short as possible. The maximum cable length that you can use depends on the types of devices in the chain. See the table below for information about maximum cable lengths:
| SCSI device | Maximum cable length |
| Ultra2 LVD | 12 meters (about 39 feet) |
| Ultra (or Ultra2 LVD devices in single-ended mode) | 1.5 meters (about 5 feet) |
| SCSI-1, SCSI-2 | 3 meters (about 10 feet) |
Terminate the SCSI Chain Properly
To ensure accurate transmission of information, a terminator must be present at each end of a SCSI chain. When you connect SCSI devices, make sure that only the last external device in the chain has a terminator. (There is already a terminator at the beginning of the SCSI chain inside your computer.)
The cable supplied for internal SCSI devices within your computer is already correctly terminated. The external cable is not terminated.
To terminate the last device in an external chain, do one of the following:
- Use a device that has a built-in terminator as the last device in the chain.
- If the device at the end of the SCSI chain does not have a built-in terminator, attach an external terminator. You can attach or remove external terminators yourself. Terminators are available at authorized Apple dealers.
Important Do not attach a terminator to a device that already has a built-in terminator. If you do, your computer may not start up properly.
Connecting an Internal SCSI Storage Device
To install an internal SCSI device, see the setup manual that came with your computer.
Connecting an External SCSI Device
To connect an external SCSI device to your card, follow the instructions below. Use these general instructions in conjunction with the more specific instructions that came with your external SCSI device.
1. Shut down your computer and make sure the SCSI device is switched off.
2. Use a SCSI cable to connect the device either to the card's external SCSI connector or to the last SCSI device already in the chain.
Use a SCSI cable that is compatible with the SCSI device. If you have a 68-pin connector on your external device, use the 68-pin VHDCI to 68-pin connector cable that came with your computer to connect the device to the card. Other cables or adapters may be required for SCSI devices with other types of connectors. For more information, see the documentation that came with the SCSI device.
Use the thumbscrews on the connectors to make a tight, reliable connection. Do not overtighten the thumbscrews.
3. Turn on all devices in your SCSI chain.
Important Always turn on all external SCSI devices connected to your computer before turning on the computer itself. Otherwise, your computer won't recognize that the SCSI devices are connected to it and your computer may not be able to start up.
4. Turn on your computer.
Icons appear for all SCSI devices connected.
Note: If you do not see an icon for a device, you may need to use drive formatting software, such as Drive Setup, to mount the device and make it available for use. Drivers installed by Apple's Drive Setup application may not be compatible with some devices.
5. Install any necessary device drivers (software that makes a device work with your computer).
Drivers needed for a SCSI device usually come on a disk or CD with the device. (If no drivers come with the device, contact the device's manufacturer.) Some older SCSI devices may require updated drivers to work with your computer.
Note: If you experience problems after connecting a SCSI device, see the troubleshooting documentation that came with your computer for possible solutions.
Technical Specifications
- Supports narrow and wide versions of Ultra-2, Ultra-1, Fast, and Standard SCSI devices
- Supports up to a total of 30 SCSI devices internally and externally (15 per channel, limited by the number of internal devices your computer is designed to house)
- Transfers data at up to 80 Megabytes per second (MB/sec) on each channel
- Supports SCSI Manager 4.3 compliant drivers only