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ATA buses generally have many fewer problems than SCSI ones. Still, in case things do go wrong, here's what you should know:

  • ATA channels: slave and master A Mac typically supports up to two ATA "channels": a primary and a secondary channel. Some Power Macintosh G3 models and all Power Mac G4 computers can have two ATA/IDE devices on the same ATA/IDE channel. One device is called the master while the other is called the slave. The internal hard drive is almost always the master device on the primary channel. In fact, only the master device can serve as a startup disk. Beyond this, the master device does not have any special status compared to the slave. The slave device does not rely on the master device in any way.

    A second hard drive, an internal CD-ROM drive and/or a Zip drive can be on almost any other combination of the remaining locations (although the Zip drive will usually be on the secondary channel). Thus, these Macs could support up to four ATA devices. These are all internal devices; there is no external ATA connection.

    Normally, you need not worry about any of this, especially if all of these ATA devices came pre-installed on your Mac. But if you start installing ATA devices yourself, it can be a concern. In particular, a device that works well as a slave may not work well as a master, or vice versa. You may also need to get into adjusting the jumpers on the device itself. This gets beyond the scope of Sad Macs. However, details should be included with the manual that comes with the device. Iomega, in particular, has a great technical manual that comes with its internal Zip drive.

    Another concern: for an ATA drive to work with a Mac, the manufacturer needs to configure it in a certain way—a way that is not done for all ATA drives (because ATA drives are also used with PC machines where some of these specifications are not needed). So before you buy an ATA drive, check with the vendor to make sure it is Mac-compatible.

    ATA channels can be of different speeds, much like SCSI buses. For example, your Power Mac could have a fast Ultra ATA bus, used for the hard drive, and a slower, standard one used for the CD-ROM drive.

  • Mounting and using ATA Drives SCSI utilities, such as SCSIProbe, do not list ATA devices. If you have an internal ATA hard drive or CD-ROM drive, don't be surprised when they appear to be missing. They will still show up in Apple System Profiler, although this cannot mount a drive. However, any formatting utility that has been updated to work with ATA drives (and this includes Drive Setup) can be used to mount any ATA drive. For Drive Setup, just highlight the drive and select the "Mount Volumes" command from the Functions menu. Similarly, Iomega Tools can be used to mount ATA (and even USB) Zip and Jaz cartridges.

    If you just want to view a list of all your SCSI and ATA devices, what bus/channel they are on, and whether or not ATA devices are slave or master devices, another useful utility is Intech Software's freeware Peripheral View.

    In general, make sure you have the latest driver software for each device, as they fix problems with older versions. For example, some first-generation Power Macintosh G3 computers came with an ATAPI internal Zip drive. You could not start up from a Zip cartridge in this drive unless you updated to version 6.0 or later of the Iomega driver. The driver had to be installed on the cartridge itself. You can also use Iomega Tools to mount cartridges in ATA (and even USB) drives.



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