In 1998, with the iMac's introduction, Apple fell into line with standard PC connection practice, and now uses the USB buss and connectors for all peripherals. PCs and older Macs have separate sockets for keyboard and mouse. Older Mac and PC peripherals often use some variation on the SCSI (small computer system interface) buss, such as SCSI-2 or SCSI-wide, with different speeds and connectors, but the system is now basically obsolete. For audio and video, or just plain fast delivery, the new choice for PC or Mac platform is FireWire, an Apple-developed system often referred to by PC companies as IEEE 1394 or i.Link. For our purposes, they mean the same. This is the fastest connection of all, able to deliver broadcast-quality video from a hard drive to a computer.

USB and FireWire have no meaningful limit to the number of devices you can connect, unlike SCSI which is limited to eight discrete 'addresses' selected by the switcher on the back of each device. USB is slightly slower than SCSI, FireWire enormously faster. There are new Mark II versions of each interface, even faster. All device types can be chained. USB and FireWire can be hot-swapped (connected without turning off the computer), but unless you have a a special adapter you must turn off before connecting SCSI devices or you may lose, for example, the data on your hard drive. Similarly, you must dismount an external USB or Firewire hard drive before pulling the cable (unless, of course, the computer is turned off). There are inexpensive interface boxes available for connecting between all three busses.