How To Connect SCSI Devices to a Mac

Small Computer System Interface or SCSI is the system used to connect devices such as hard disks, scanners, CD ROMs, or printers to the Mac. You can have several devices connected to the Mac at the same time using the right type of SCSI cable for each type of connection.

1. Change the SCSI device numbers. On all SCSI devices there are switches to change the ID number. You have to set each SCSI device with a unique ID number to enable the Mac to tell one SCSI device from another. On the back of the SCSI device, change the number so each one will have a different number. Do not set another device with the same number, or it may cause the device and your computer to malfunction. You can use up to seven numbers, but the number seven is set for your Mac and the number zero is usually the default number for the internal hard disk.

2. Shut down the Mac. Make sure you turn off your Mac before making any connections, and make sure all the SCSI devices are turned off as well to prevent power surges and damage to both the Mac and SCSI devices.

3. Connect the SCSI cable. Attach one end of the SCSI system cable to the SCSI device and the other end to the Mac. Check which end attaches to the Mac and which one attaches to the SCSI device if each end is different. Tighten screws and/or fasten the clips if there are any, and make sure they are secure. If you have another SCSI device, attach a peripheral interface cable to the SCSI device's output and then the other end to the second SCSI device. You can link up to seven devices together.
4. Place SCSI terminator. You should terminate the last SCSI device so an electrical signal does not surge back to the SCSI device chain and cause disturbances in the signal or damage to your SCSI devices and Mac. You may have to use a plug in between the device and the cable to set the termination or flip a switch to accomplish this. Check the device and check the manual that came with the device to make sure which kind of terminator the SCSI device uses.
5. Connect power cables. When all the SCSI devices are link together, you can attach the power cable on each device and plug it into the power outlet or surge protector. Switch on each device then turn on the Mac. You should be able to see the SCSI devices attached to the Mac on the desktop.

You can now use the SCSI devices that you connected to the Mac. Check each connection to make sure they are all secure before turning on the devices and the Mac.