Pick and Install the new MODEM          AE Systems 11/98

First, you modem choice is top priority. We have been selling the Motorola On-line SURFR and modem SURFR lines from the 28.8 days to the newer 56K with voice. They are great products. They even work  with WIN95, which is a beast if the hardware is poop. Unfortunately, Motorola discontinued this modem line and does not have a replacement. Another good brands is Multitech System or Maxtech if you want a low cost product. Spending a little more for a good, solid product will save a lot of cursing and hair pulling down the road. If you want voice mail you will need to buy an internal model.

Beware that a lot of the new internal modems are PCI models. The reliable ISA modem is getting hard to find rather quickly.

Most of them require a minimal CPU of a Pentium 100 or higher to connect the PCI bus to the PC as a COM port. A slow PC might work, but you are likely to get a modem that won't talk to the PC even though resources for the modem are correct. Be sure to read the box before you buy it. If you have an older PC try to find a good ISA modem. Another alternative is to use an external modem. As long as your COM ports are 16550 or better, these will always work!

COM Port 101:

The traditional PC has 4 main COM ports:

COM1 0x3F8            IRQ 4
COM2 0x2F8                    3
COM3 0x3E8                    4
COM4 0x2E3                    3

These are the default addresses and interrupts, IRQ settings, for the four ports. PCs always come with two COM ports, COM1 and COM2. If you have a serial mouse it is on COM1 99% of the time. Most newer PCs use a PC/2 mouse, however. PS/2 mice do not use a COM port but do use an interrupt, IRQ12. It is a trade these days. IRQs are at a premium in new PCs, so it might be advantageous to use a serial mouse just to save an IRQ. For more evils on this subject please check out the IRQ map page on this web site.

In either case, modems MUST have their own address, COM port, in WINDOWS, WIN95, NT, whatever, to run correctly. It is nice to have your own IRQ, but you can get around it if you are careful. With new Plug and Play hardware your modem may end up with say, COM4 IRQ9, or COM3 IRQ15. This is perfectly fine for newer MBs and modems. What you can't get around is sharing an IRQ with the mouse!

Notice from above that COM1 and COM3 share the same interrupt by default. If your mouse is on COM1 and the modem on COM3 IRQ4, every time you move the mouse the modem would burp...not good. This is why a lot of modems come with COM3 IRQ5 as an option. That way you don't have any conflicts. Well, that is the idea anyway. IRQ5 is usually used for a sound card, so COM3 IRQ5 isn't necessarily safe.

All PnP hardware wants to have a unique address and IRQ. This statement is true for all PnP hardware - SCSI controllers, ethernet cards, sound cards, etc. That way neither the address or IRQ conflict with any devices in the PC. It makes life easier for the software developers, but it chews up interrupts. Drivers have to be written to tell the OS what the settings are for the hardware whenever they might change. Adding a new modem to the PC might change a lot of hardware settings. As long as the system setups get updated all is well. For OS such as NT and UNIX moving hardware settings causes grief, since PnP isn't supported too well.

In the quest to be unique some strange settings can pop up. A PnP modem, such as the Motorola VoiceSurfr 56K Internal ( only Internal modems are PnP ) may set itself to COM3 IRQ5. This is not a standard setting for COM3. A WIN95 driver would automatically update the configuration files. WIN 3.1 and NT would not!  In WIN 3.x, you have to go to the ports advanced settings and tell it that you have a nonstandard IRQ. Otherwise it will look at standard settings and nowhere else. For example, your modem could be fine at COM4, IRQ11 without conflicts. But because of PnP, the software will try to use COM4 IRQ3. Nothing will happen. The modem is dead. Dealing with PnP hardware in a non PnP OS is a major pain in the butt!

Now if you have a sound card, it uses IRQ5. No modem can share the IRQ with a sound card. That is a Bozo no-no. The parallel port uses IRQ7, so that IRQ can't be used either. You have no free low IRQ values left. In this case the modem would hop to COM3 or COM4 IRQ9, for example.

PnP only works well if device in question supports it, in this case the modem, the MB supports it, and your OS handles PnP hardware and software well. If all of these conditions can be met, then you can find some happy settings. WIN95 is particularly good at this. You might get COM4, IRQ9, but it will work.  Doing the PnP dance with WIN 3.x isn't easy at all. It stinks.

A lot of older PnP modems, especially US Robotics, are only half PnP ready. By this I mean the PnP settings are very limited. The modem might only have access to the lower IRQ settings, 2, 3, 4, 5, and 7. This is the case of the USR 33.6 modem. Well, on any modern PC, all of these are already taken by the on board ports and the sound card. See the IRQ map. These modems aren't necessarily cheap in price either. The manufacturer decided to make an 8 bit, ISA card which only has access to the lower IRQ settings on the bus. They got lazy or arrogant. You will pull your hair out trying to make it work, but the PnP settings for the modem aren't wide enough to work The only solution is to go into the device manager and move the sound card, for example, to IRQ10 to free up a lower IRQ. The best solution is to use a better modem in the first place that will use any free IRQ in your system.

I strongly recommend that you do not use PnP if your MB doesn't support it without any extra software. It is not worth any gain.

Possible Setup Options:

If your modem is PnP ( really PnP!!), good,  new, and if you have a quality system, chances are you can put it in and turn on the switch. When the OS starts, WIN95 or '98 for example, it will ask for a driver disk after it detects the modem. Feed in the disk and you should be set. All of the hardware will self adjust for the new modem. After the PC cycles a few times, all of your hardware should be running at full speed. That is how PnP is supposed to work. Older modems might be a wet blanket on your PC, so read on.

1)If your modem is non PnP (External or just older) set the modem to COM2, IRQ3 NON PnP and make sure the existing COM2 is off for an internal modem. New machines can do that from system BIOS at boot time. Make sure any other modem is out of the machine. Older machines will require jumper settings inside the box to be changed for COM ports.

To verify COM2 isn't alive, pull the old modem out if there is one and restart the PC. When the PC boots a screen comes up that system info: hard drives, floppy, BIOS date, RAM in the PC, etc. On the lower right side you will see SERIAL ports or COM ports just above PARALLEL ports. The addresses will appear for a few seconds only. If you see 3F8 only you are cool. Install the modem at COM2 IRQ3. If you see 378, 2F8, then you have a COM1 and a COM2. COM2 must be moved or disabled.

2) Set the modem for COM4 IRQ3 NON PnP. That almost always works, conflicts or not because no one has 4 COM ports in their machine. Therefore, COM4 is always free. You will be sharing the IRQ of COM2, but that isn't a big deal usually. COM2 is seldom used. Therefore IRQ3 is pretty safe. If you have an ATI video card, COM4 can't be used. Most ATI cards use part of the address range of COM4 for control of the video BIOS chip.

3) Set the modem for COM2, IRQ3 NON PnP and set the internal secondary COM port to COM4. This is just the reverse of case 2 above, but it assumes that the existing COM2 can be moved. It also gets rid of the ATI video card conflict for a modem that might be set to COM4.


Options 1,2 and 3 work. I set up the machines that I sell for modems on COM2, usually if modem doesn't support PnP or if it is an NT box. Then I move the machine's original COM2 to COM4 or just turn it off.  If it is a WIN95 machine, I'll use the PnP feature. The modem will come up at COM3 IRQ10 ( first free IRQ), or COM4 IRQ9.

4) Use COM3, IRQ5 WITHOUT a sound card. IRQ5 is only busy if a sound card is there. You will have to tell DOS applications and WIN 3.x that you have a nonstandard IRQ setting for COM3. It will look at IRQ4 otherwise, where the mouse is. I have an E-MAIL machine without a sound card that does just this--COM3, IRQ5.

5) Buy an external modem instead. Why? Because that COM2 connector (DB25M or a second DB9M in newer PCs) in the back of the machine DOES work. It did from day one when you bought the PC, so it still does; we hope. Then install the modem software. It will find the modem settings for you. The danger is that if the machine is old, ( really old...old 486 class ) the external serial port might be too slow for even a 14.4 modem.

6) The new USB modems are out as of 10/98. Multitech Systems makes a nice V.90 56K modem for USB. USB only works in WIN98 and new '95 PCs, but you can just plug it in and load a driver for your modem. The USB port requires no hardware drivers once setup by your PC builder. You will not have to open your case for card changes or make any IRQ changes to your system. For Sys Admins, this is a huge win.

USB modems include drivers that trick the PC's COM port map. The PC will think that it talks to the modem on COM3 IRQ4, for example. Under Device Manager, a USB modem is actually several pieces of hardware. You don't have to worry about IRQ conflicts. This is a software remap only; no actual hardware conflicts exist.

Software Driver Setup

For PnP modems in WIN95, driver installation is very easy. If the PC has no hardware conflicts, it will see the new modem at boot and ask for the driver disk. Insert it. Your done. Simple. For NT you will still have to tell the OS what the settings are. The modem manual can help here. The PnP drivers see the modem but don't tell NT what the settings are -- strange but true. Figuring out what COM and IRQ the modem went to can be a challenge. After much  pain you will either get the correct settings or chicken out -- you will turn PnP off and lock the settings to a standard value such as COM2 IRQ3.

For non PnP hardware life gets fun. In WIN95, you may need to launch the Add New Hardware wizard from within the control panel. Let it search for new hardware. The first time through it will find the new COM port, which is the COM port of your new modem. Or you can manually add the COM port and bypass the wizard. Then reboot the PC and run the wizard again. Now WIN95 will find the modem attached to the new COM port. Then insert your driver disk.

For external modems run the hardware wizard for modems only. It will find the external modem, probably at COM2 IRQ3. Then insert the driver disk when prompted.

Sometimes a PnP modem might need a kickstart to wake up. Manually adding a COM port where that the modem lives on will start the process. It sounds strange, but it does work. If your modem is on the address for COM4, for example, and the PC still can't see it, then add the port. As soon as you do that the PC will find your modem as a device connected to this COM port.

If everything went well, go to the Modem ICON in Control Panel. Open it.

modem1.gif (59522 bytes)

In this case the modem is an External Hayes 28.8.  Click on the Diagnostics tab.

modem2.gif (51170 bytes)

Select the COM port with the modem attached. In this case it is clearly COM2. Then click o the More Info button.

modem3.gif (53246 bytes)

All of the modem's settings and responses to standard AT commands show up. Some errors might show up, since not all modems do not respond to the same AT command set.

updated 11/98

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