• Create BookmarkCreate Bookmark
  • Create Note or TagCreate Note or Tag
  • PrintPrint

Why to Do It:

Ports and buses If you want to add any device to your Macintosh, there is an assortment of ways to do so. Each method has its own functions and limitations, advantages and disadvantages. Here is a brief overview of the major types of ports used to connect devices:

  • Serial ports The iMac signaled the end of the serial ports. No Macs released since the release of the iMac have them. Traditionally, there are two separate serial ports, a modem port and a printer port (although some models, especially PowerBooks, just come with one port). The names give away their function: these ports are mainly used for connecting to modems and printers. They are also used for hooking up a Mac to a LocalTalk network, including "networked" printers, such as most laser printers. Despite their different names, the two ports are virtually identical and can generally be used interchangeably.

    For the iMac (and newer Macs), these functions have been taken over by the USB and/or Ethernet ports, as well as (in some Macs) by an internal modem slot.

  • Apple Desktop Bus (ADB) Until the iMac and USB came along, this was the bus that was used to connect your keyboard and mouse. Other input devices, such as pen tablets, might also use it. Beyond that, it was not used much. Apple's blue-and-white G3 Macs still have one ADB port, as a legacy input option. With the Power Mac G4, Apple dropped the ADB port altogether.

  • Universal Serial Bus (USB) This bus is included on the iMac and all Macs shipped since the iMac. It is used to connect the keyboard and the mouse. It is also used to connect all non-networked printers (such as most Epson Stylus Color printers). Finally, it can be used to connect any of a large variety of other peripherals, from digital cameras to scanners to Zip drives and SuperDisk drives. As a replacement for serial ports, they are much faster. As a replacement for SCSI ports, they allow more devices to be connected and are easy to work with (for example, there are no problems with connecting or disconnecting a device while the Mac is on). However, the USB port is much slower than a SCSI port, so you cannot read and write to a USB hard drive nearly as fast as a SCSI one.

    One big advantage of USB over SCSI is that USB is also popular on PCs. This means that USB devices for the PC can be easily adapted to run on a Mac. Generally, all that is needed is to create a new software driver; no hardware modifications are required. This means that cameras, joysticks and even printers designed for the PC can easily run on a Mac as well. Because SCSI was largely restricted to the Mac and required special hardware, manufacturers too often rejected a move to the Mac platform as not cost-efficient if a SCSI implementation was needed.

  • Small Computer Systems Interface (SCSI—pronounced "scuzzy") Starting with the Macintosh Plus, and ending with the last Macs before the iMac, all models of Macintosh had a port in the rear of the machine called the SCSI port or SCSI bus. You used this port to connect most external hard drives, CD/DVD-ROM drives, scanners, and backup devices. You could even use it to connect a PowerBook to a desktop Mac. It was the most high-speed port available on the Mac, and thus the preferred port for all high-end non-networked devices or whenever the maximum in speed was desired.

  • Integrated Drive Electronics (IDE); also known as Advanced Technology Attachment (ATA) IDE and ATA mean almost the same thing. IDE (ATA) was originally designed for hard disks only, not removable devices such as Zip or CD-ROM drives. To accommodate this, Advanced Technology Attachment Packet Interface (ATAPI or just ATA) was created. ATAPI devices still use the same old IDE connector. IDE was originally developed on the PC. IDE is slower but less expensive than SCSI. As such, the first Macs to employ IDE used it as a less expensive alternative to SCSI for the internal hard drive. These were the low-end (now extinct) Performa Macs. Over the years, the speed capability of IDE has improved to the point where it now rivals SCSI. As such, even high-end Macs now come with internal IDE hard drives and CD-ROM drives.

  • FireWire If you followed along through all of this, you may have noticed that, with the demise of SCSI on Apple's newest Macs, the Mac lost its fastest external port. To replace SCSI, Apple introduced FireWire. From a troubleshooting perspective, it eliminates almost every problem that plagued SCSI: it is faster (much faster) than SCSI, you can connect as many devices as you could possibly want, there are no issues with cable length, ID numbers, and termination (as described here shortly) and you can even "hot-swap" (connect and disconnect) FireWire devices while the Mac is on. FireWire even supplies its own power source, so low power FireWire devices can work without having to be plugged into an separate wall outlet. This is clearly the wave of the future.

Cables and icons Each type of port is different and has its own cable associated with it, as well as its own icon symbol used to identify the port and cable. Figure F14-1 shows the icons for SCSI, USB and FireWire.

  • SEE "By the Way: SCSI Cable Connection Confusion," later in this Fix-It, for more details on the various SCSI connectors and ports.

Problems Each type of port also has its own problems. If you have SCSI, ATA, USB, FireWire and/or ADB devices connected to your Mac, and they all work as expected, you can skip the rest of this Fix-It for now. But if anything isn't working quite right, read on. As you will soon see, problems here can often be traced to problems with how these devices are connected, what cables are used, and settings on the device itself.

Note that some of the more general advice in the SCSI section of this Fix-It also applies to other sections. For example, Iomega makes SCSI, ATA, and USB Zip drives. While some Zip issues are specific to the exact device, others will apply to all the Zip drive variations. So no matter what type of drive you have, look over the SCSI section for possibly relevant information.

Finally, note that many of the symptoms described here (such as system crashes) have other causes besides "port" problems. These other causes are covered throughout this book, as appropriate.

Figure F14-1. The FireWire (left), USB (center), and SCSI (right) icons.



Not a subscriber?

Start A Free Trial

  • Creative Edge
  • Create BookmarkCreate Bookmark
  • Create Note or TagCreate Note or Tag
  • PrintPrint