Một cuộc khảo sát được thực hiện một khi trở lại để tìm hiểu lý do tại sao một số người không sở hữu một máy tính. Lý do số một? (Bạn có thể đoán) Không, nó không phải là máy tính là quá đắt. Lý do số một mà mọi người không mua máy tính được rằng họ đã không tìm ra những việc c | __Chapter 10 Expansion Options 111 Optional information on infrared ports Another type of port found mostly on laptop and other portable computers is the infrared IR port. It allows other computers with infrared ports to connect and share data though it may also be used to connect a computer wirelessly to some device. For this reason this port isn t considered a standard on most desktop computers. About the only place it s standard is on various handhelds where the IR port can be used to quickly beam information between two systems. The serial port The serial port was the original versatile computer port. Used primarily with early computer modems the serial port could also connect a mouse scanner printer or a number of other interesting devices to a computer. The serial port is now generally used to connect an external modem to a computer. See Chapter 11 for more information on modems. The serial port may also be used to connect two computers for file-exchange purposes. And some PCs still use it to connect a computer mouse. Beyond the simple options I mention the serial port has really fallen out of favor recently. In fact in a few years it may vanish from the computer s rear end replaced by the more efficient USB port. A serial port is no longer required for most PCs. Even so some desktop model PCs sport two serial ports. A serial port has two different types of connectors the smaller 9-pin D-shell connector and the larger 25-pin D-shell connector. Most PCs now use only the smaller 9-pin connectors. If your computer has a larger 25-pin connector be careful not to confuse that port with the printer port which also has 25 pins. The Mac doesn t have a serial port and instead uses the USB port to attach devices. Serial ports have a variety of different names used to describe them modem port COM1 the old IBM PC name AUX mouse port and RS-232C port. 112 Part II Hardware and Software Overview The monitor port The monitor port is
