Some Power Macintosh G3 computers and all Power Mac G4 computers can have two ATA/IDE devices on the same ATA/IDE channel (commonly known as master and slave). The Power Macintosh G3 Minitower, Desktop, and All-in-one computers were the first Macintosh computers to use master/slave configurations.
Computers That Support Master and Slave
Master/slave configuration allows you to add additional hard disk drives or removable media drives to a computer. Despite the hierarchical-sounding names of "master" and "slave", the master drive does not have any special status compared to the slave.
You can install two ATA/IDE devices on the same ATA/IDE channel in a master/slave configuration on these computers:
- Power Mac G4
- Power Macintosh G3 (Blue and White) (limited to certain configurations)
- Power Macintosh G3 All-in-one
The Power Macintosh G3 (Blue and White) computers that support dual IDE drives have a U bracket installed in the rear drive bay. This allows two hard drives to be installed in that bay. Refer to Figure 1 to identify the U bracket.
Figure 1 Hard Drive "U" Bracket
The original Power Macintosh G3 Minitower and Desktop computers may or may not work with this feature. Original Power Macintosh G3 Minitower and Desktop computers with a revision 2 or later logic board support this feature. You can use the Apple System Profiler application to determine which revision of the logic board is installed in your computer. If the logic board has the ATI RAGE PRO chip, the computer has a revision 2 or later logic board.
Configuring or Connecting
Each IDE channel can work with either one or two devices. All Power Macintosh G3 computers have two ATA/IDE channels. To maintain order on the channel, it is necessary to have some way of differentiating between the two devices. This is done by giving each device a designation as either master or slave, and then having the controller address commands and data to either device.
Devices are designated as master or slave using jumpers on the controller board of the drive. If you are using two drives on one channel, make sure they are jumpered appropriately. Setting both drives as master, or slave, may cause unpredictable behavior.
It makes no difference which connector on the ATA/IDE cable is used in a standard ATA/IDE setup because the jumpers control master and slave status, not the cable. As long as one device is jumpered as master and the other as slave, any two ATA/IDE or ATAPI devices should work together on a single channel.