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or receive data. These extra wires are called ready to send (RTS) and clear to send (CTS), so hardware handshaking is often called RTS/CTS. Software flow control uses a special character called XON to signal that data flow is beginning, and another special character called XOFF to signal that data transmission is finished; therefore, software handshaking is often called XON/XOFF. Software handshaking is slower and not as dependable as hardware handshaking, so you rarely see it.

Bells and Whistles Although the core modem technology has changed little in the past few years, modem manufacturers have continued to innovate on many peripheral fronts—pardon the pun and the bad grammar. You can walk into a computer store nowadays, for example, and buy a V.92 modem that comes bundled with an excellent fax machine and a digital answering machine. You can even buy modems that you can call remotely that will wake up your PC (Figure 25-12). What will they think up next?

Figure 25-12 Some of the many features touted by the manufacturer of the SupraMax modem

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NOTE You can test a modem by plugging in a physical device called a loopback plug, and then running diagnostics.

Modem Connections Internal modems connect to the PC very differently than external modems. Almost all internal modems connect to a PCI or PCI Express expansion bus slot inside the PC, although cost-conscious manufacturers may use smaller modems that fit in special expansion slots designed to support multiple communications features such as modems, NICs, and sound cards (Figure 25-13). Older AMD motherboards used Audio/Modem Riser (AMR) or Advanced Communication Riser (ACR) slots, while Intel motherboards used Communication and Networking Riser (CNR) slots.

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NOTE AMR, ACR, and CNR slots have gone away, though you’ll still find them on older systems. Current systems use built-in components or PCIe ×1 slots for modems, sound, and NICs.

Figure 25-13 A CNR modem

External modems connect to the PC through an available serial port (the old way) or USB port (Figure 25-14). Many older PCs came with 9-pin serial ports, whereas most external modems designed to connect to a serial port come with a 25-pin connector. That means you will probably need a 9-to-25-pin converter, available at any computer store, to connect your external modem. Serial ports are now quite rare as virtually all computers today have two or more USB ports.

Figure 25-14 A USB modem

Don’t fret about USB versus serial for your modem connection, as the very low speeds of data communication over a modem make the physical type of the connection unimportant. Even the slow, aging serial interface more than adequately handles 56 Kbps data transfers. If you have the option, choose a USB modem, especially one with a volume control knob. USB offers simple plug and play and easy portability between machines, plus such modems require no external electrical source, getting all the power they need from the USB connection.

Dial-up Networking

The software side of dial-up networks requires configuration within Windows to include information provided by your ISP. The ISP provides a dial-up telephone number or numbers, as well as your user name and initial password. In addition, the ISP will tell you about any special configuration options you need to specify in the software setup. The full configuration of dial-up networking is beyond the scope of this book, but you should at least know where to go to follow instructions from your ISP. Let’s take a look at the Network and Internet Connections applet in Windows XP.

Network Connections To start configuring a dial-up connection in Windows XP, open the Control Panel. Select Network and Internet Connections from the Pick a category menu and then choose Set up or change your Internet connection from the Pick a task menu The Internet Properties dialog box opens with the Connections tab displayed (Figure 25-15). All your work will proceed from here.

Figure 25-15 The Connections tab in the Internet Properties dialog box

Click the Setup