2400 BPS External Modem (250-3026) Connections Faxback Doc. # 5032 Serial Connection Information: To connect the modem to your computer, the computer must have an unused serial port, also known as an RS-232 interface. The jack that you plug this serial connection into comes in several different shapes, but the most common by far is the DB-25 connector, followed by the "DB-9" on older Macintosh computers, and the "Circular 8" on the Mac Plus and the Mac SE. These connectors are illustrated on the following page. On computers with plug-in expansion slots like the IBM PC and compatibles, the serial port is normally part of an expansion card, and therefore can be found at the expansion card slot openings at the back of the PC. Many other machines, particularly those without expansion slots (including laptops and other portables), have the serial port built-in. Either way, it will normal- ly be labeled "serial port" or "RS-232C". The Serial Cable: External modems normally do not come with serial cables, since each computer requires a different cable depending on the type of serial connector it uses and how that connector is wired. Since the serial port of this modem is compatible with the Hayes 2400 exter- nal modem, the easiest way to specify the correct cable to your computer dealers is by asking for the cable to connect a Hayes 2400 modem to your brand and model of computer. Making the Serial Connection: Once you have the proper cable to connect the modem to your computer, the most difficult part of the job is done. To complete the serial connection, just plug the cable into the connectors on the modem and the computer, and if the connectors have locking screws, turn them until they are tight (but not too tight) to hold the connectors in place. Phone Line and Telephone Connections: There are two standard modular phone jacks (RJ11C) on the modem. One of these jacks goes to the wall jack where your would normally plug in a stand- ard single-line telephone. If you would like, you may plug a standard single- line phone into the other. You do not need to plug in a phone to use the modem, but you may find it convenient to have a phone beside your computer. The two phone jacks on the modem are interchangeable. You may plug the telephone or the cord connecting the modem to the phone line into either jack. The cord provided for connecting the modem to the phone line has a modular RJ11 plug on both ends, If your phone system does not have modular jacks, you will need a modular adapter, sold at your Radio Shack Store or any place that telephone accessories are sold. (smm 07/28/93)