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USB’s main attraction is that it makes adding peripherals to your computer incredibly easy. It enables you to connect peripherals to the outside of the computer so you don’t have to open your PC.

A USB peripheral simply plugs right into the port and works. You don’t need to install a card; you don’t even need to turn off your computer. Because USB configuration happens automatically, built-in USB means you don’t have to fiddle with drivers and software when adding most peripherals.

USB 1.1, the original USB standard, has two data rates: 12 Mbps for devices, such as disk drives, that need high-speed throughput and 1.5 Mbps for devices, such as joysticks, that need much lower bandwidth.

In 2002, USB 2.0, Hi-Speed USB 2.0, gained wide acceptance in the industry. It increases the speed of the peripheral-to-PC connection from 12 Mbps to 480 Mbps, or 40 times faster than USB 1.1. This increase in bandwidth enhances the use of external peripherals that require high throughput, such as CD/DVD burners, scanners, digital cameras, and video equipment. USB 2.0 also supports demanding applications where multiple high-speed devices run simultaneously, such as Web publishing. A USB 2.0 host will work with both USB 2.0 and USB 1.1 peripherals. USB 2.0 also supports Windows® XP through a Windows update.

Another USB standard, USB On-The-Go (USB OTG), has also been developed. USB OTG enables devices other than a PC to act as a host. It enables portable equipment—such as PDAs, cell phones, digital cameras, and digital music players—to connect to each other without the need for a PC host.

There are four types of USB connectors: Type A, Type B, Mini B, and Mini A.

USB 1.1 specifies the Type A and Type B. USB 2.0 specifies the Type A, Type B, and Mini B. The Mini A connector was developed as part of the USB OTG specification and is used for smaller peripherals, such as cell phones.

The Digital Visual Interface (DVI) video standard is based on transition-minimized differential signaling (TMDS). In a typical single-line digital signal, voltage is raised to a high level and decreased to a low level to create transitions that convey data. To minimize the number of tran-sitions needed to transfer data, TMDS uses a pair of signal wires. When one wire goes to a high-voltage state, the other goes to a low-voltage state. This balance increases the data-transfer rate and improves accuracy.

Although there are four types of DVI connectors, only DVI-D and DVI-I are commonly used for monitors. DVI-D is a digital-only connector. DVI-I supports both digital and analog RGB connections.

The Digital Visual Interface (DVI) standard is based on transition-minimized differential signaling (TMDS). In a typical single-line digital signal, voltage is raised to a high level and decreased to a low level to create transitions that convey data. To minimize the number of transitions needed to transfer data, TMDS uses a pair of signal wires. When one wire goes to a high-voltage state, the other goes to a low-voltage state. This balance increases the data-transfer rate and improves accuracy.

There are different types of DVI connectors: DVI-D, DVI-I, DVI-A, DFP, and EVC. DVI-D is a digital-only connector.

DVI-D is a digital-only connector. DVI-I supports both digital and analog RGB connections. Some manufacturers are offering the DVI-I connector type on their products instead of separate analog and digital connectors. DVI-A is used to carry an analog DVI signal to a VGA device, such as a display. DFP, like DVI-D, was an early digital-only connector used on some displays; it’s being phased out. EVC (also known as P&D) is similar to DVI-I only it’s slightly larger in size. It also handles digital and analog connections, and it’s used primarily on projectors.