Improving the External Bus

As discussed previously, high bandwidth audio has been a problem inside the PC, and the PCI bus is playing a large part in alleviating that problem. But, the PCI bus can’t be used outside the PC’s case. To make the move to the case’s exterior, one used to have to use the serial port, with the pathetic 115-Kbps bandwidth. Obviously, the kind of equipment that will actually work well at this low bandwidth is limited, and audio equipment is definitely not on that list. For high quality audio related peripherals, we have to turn to higher tech buses, namely the Universal Serial Bus (USB) and IEEE 1394 (FireWire).

USB is designed to replace the serial port. Most motherboards now come with support for USB, and, with the release of Windows 98, we now have operating system support as well. USB allows a transfer rate of 12-MBps and can support up to 127 different devices in a daisy chain. All of these devices are plug-and-play and can actually be “hot-swapped”, meaning they can be removed and installed while the PC is operating. How it works is one USB device is actually plugged into the USB port. Then, that device works as a hub for the other devices.

What does USB mean to the audio industry? Well, plenty. A couple USB ports can replace all of those audio connectors on the back of your sound card. This can include speakers, microphones, etc. Also, USB allows manufacturers to move the audio-signal processing to the exterior of the case, minimizing the loss in audio quality which occurs due to the electrical noise within the PC’s case. Instead, the audio processing can actually be placed in the speaker system. This improves audio quality, and can actually alleviate the need for a separate sound card altogether.

IEEE 1394, nicknamed FireWire, is the fastest type of external bus I’m aware of. It supports bandwidths from 100 to 400-Mbps, with future versions offering incredible 1-2Gbps bandwidths. FireWire’s bandwidth is perfect for connecting such things as camcorders and audio/video hardware to the computer. These types of hardware must have high bandwidth in order to deliver full motion video to the PC. The structure of FireWire is like that of USB, meaning it works in a daisy-chain and supports hot-swapping.

High speed technologies such as USB and Firewire will turn the PC into a controller for entire home entertainment center, all of the components being simply peripherals of your home PC.