Modems

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Modems

Windows XP Poll

Info Today, an increasing number of people are purchasing computers to go online. With this thought in mind, the hardware necessary to connect to the internet and to network machines is very important. A modem is a device that lets your computer communicate with other computers over a standard telephone line. It is short for modulator/demodulator. This term means that the modem converts the digital information from your computer to an analog signal that travels over phone lines. The receiving modem then converts the analog signal back to a digital signal for the receiving computer to work with. Some modems can exchange data only. Others, called fax/modems, can exchange data and fax messages. The best kind are fax/modems with voice capabilities, allowing you to use your computer like an expensive answering machine.
Internal and External Modems INTERNAL MODEM Installing an internal modem can be real easy or your biggest nightmare. Either way, being an internal card, it is harder to install than an external modem. Turn the power off, unplug it, and take the case cover off. Now choose a motherboard slot for your modem. Most modems require an 8-bit slot. Some may require a 16-bit slot. 16-bit slots are longer than 8-bit slots. Your motherboard probably has both. Try to pick a slot with room on either side to give your modem plenty of room. Remove the corresponding metal slot insert from the back of the computer. Save the screw to use for your modem. Remove the modem from it's packaging. Handle it by its edge to avoid static electricity. Don't mess with its connector pins or the chips on the board. Push the modem into the slot. You might need to roll the card into the slot because it is a snug fit. The back plate of the modem should line up with the open hole in the back of the case. Tighten the modem into place using your saved screw. Now attach the phone lines to the modem. The line from the wall jack goes to "Line" on the modem. Then, if you want to, you can connect your phone to the other jack on the modem, labeled "phone". Now reconnect all the cables and turn the computer back on. Its probably best to leave the case off until you have tested the modem, just in case you need to remove it again. The computer should boot normally. If you are using Windows 9x, and your modem is plug-n-play, your computer should detect the new modem upon startup and ask for drivers. If the modem is not automatically detected, try setting the modem manually to a free COM port and IRQ. This is done by adjusting the jumpers on the modem itself. Once it is sensed by Win95, just follow the instructions to install the software and drivers. Under Win3.1, you can first test your modem in Terminal, under Accessories. Type a command, like AT, in the box. If it responds with OK, the modem is probably working. If you can't type, or you get an error, your modem is not set correctly. You need to choose a different COM Port or IRQ. If it is working, install the software. Configuration Making an internal modem work can be a real nightmare because of IRQ and COM Port conflicts. Your modem cannot share an IRQ or a COM port with any another device. To change your modem settings, you'll need your manual. Most modems come configured for a certain setting. If this doesn't work and causes conflicts, you'll need to change it. Most modems have jumpers, and you simply move the bridge(s) to cover whatever pins are required for your desired setting. Again, consult the manual for the jumper configurations. Other modems have DIP switches. Newer modems are plug-n-play and will configure itself, but a good plug-n-play will have the jumpers available just in case it can't configure itself. During installation of the modem, you will be asked to select what type of modem you have from a list. Try to pick the exact modem. If it isn't there, try picking one as close as possible, such as the internal version of the same modem for an external modem. If you can't find any of these, usually picking a standard Hayes compatible setting will work. This will usually get you online so that you can look for better configurations at the manufacturer's web site or BBS. Most modems do not require a driver. If yours does, it is called a "host-controlled" modem. This means that the error-checking is done by the software, not the hardware. These modems can be problematic and are best avoided. If the modem box says "requires Windows", it has a high chance of being a host controlled modem. EXTERNAL MODEM Installing an external modem is relatively easy. You don't even have to open the case. All you need is a flathead screwdriver and a modem cable. Your modem may not come with a modem cable, so check the packaging. Before messing with anything, its best to create a system disk. Grab a formatted diskette and copy your Autoexec.bat, Config.sys, Win.ini, and System.ini files to it. Now you'll have copies of these files from when they were last working. The modem installation will make changes to these files, so it is good to have a way out. Turn off the computer. Take your modem cable, connect one end to the computer's port and the other to the back of the modem. Tighten the plugs in, usually by tightening the screws on either side of the connection. Make them snug, don't strip the threads. Now connect the modem to the phone cord to the wall. Plug this cord into the "line" jack on the modem. If you want to use a phone too, use the line that came with the modem and run it from the phone to the jack on the modem labeled "phone". Now plug the modem in to the wall electrical outlet. Now, turn on the computer and the modem. If the lights on the modem are working, you are ready to install the software. If they are not working, doublecheck all the connections. If these are fine, you may have the wrong modem cable or a bad modem. Install the software. Follow the on-screen commands. Choose a COM port that corresponds to the port you plugged it in to. If your modem is plug-and-play, the Windows 95 Installation Wizard will walk you through this. Speed Considerations If you're planning on using a 28.8, 33.6, or faster external modem, make sure you have a 16550 UART, or Universal Asynchronous Receiver/ Transmitter. This manages the communication between your modem software and the modem. Your modem may be able to operate at 115,200 bps, but with a slower UART, like 8250 or 16450, you will have data loss at these transfer speeds. You can check your UART through a number if different diagnostic programs. Most modern computers have an adequate UART. If you can't find out, just keep this in mind if you have problems later. If you do have an older UART, slow the software down. Choose 9600bps or 19200bps. Even if you have a fast modem, your software will then limit the modem to this speed. The good news, though, is that internal modems don't have to worry about this because they have an updated UART on the card. This overrides the one on your computer. Only external modems are limited by the computer's built-in UART. The only way around it if it is limiting you is to buy a new I/O card.