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HOW TO DETERMINE IF YOU HAVE A HARDWARE CONFLICT
Determining What Serial Ports Are Installed In Your Computer
The most common configuration of Com Ports for computers is a Serial I/O card set to Com 1 and Com 2. If you install your Internal Modem to the factory default of Com 2, YOU WILL HAVE A HARDWARE CONFLICT! Before installing the modem into your computer it is a good idea to determine what serial ports are installed in your computer... if any. You may assume that you have only Com 1 on your computer, when you actually have both Com 1 and Com 2. You also might have many other combinations of Com Ports. Most computers have a Serial I/O (Input/Output) card installed with Com Ports 1 and 2 enabled. These cards allow you to connect with external modems and a mouse... just to name a couple. Even if you don't have any thing connected to the RS232 jack on the I/O card, it is still using a Com Port. A Com Port may only be used by one device. Many problems you may experience are caused by configuring the modems Com Port to a port already installed in your computer system. One symptom of this conflict is the modems inability to dial or respond to a command. Hardware conflicts can also cause very strange and intermittent problems such as working one day and not the next, or garbage displayed when connecting to another modem, or working as a fax and not as a modem, or visa versa. To alleviate this conflict you must first determine which Com Ports are available and which Com Ports are already being used. Recalling that each Com Port has a specific address assigned to it, we can use a diagnostic program that is available with both MS-DOS 6.0 or Windows 3.1. The program is named, "MSD.EXE", and can usually be found under you DOS or Windows directory.
USING MSD.EXE TO DETERMINE COM PORT'S ON YOUR SYSTEM
The MSD.EXE diagnostic utility has several useful utilities but for our purposes we will only use the Com Port scanning function. To start MSD.EXE, type MSD at the DOS or Windows prompt. After starting MSD.EXE, the display will show two columns of information ranging from the type of computer you have to the type of devices that are available on your computer. Next to the COM Port information is a number showing the number of Com Ports on your system. Now that we know how many Com Ports are on the system, we must know which Com Ports are being used. Type C to run the Com Port scanner. The following is an example of what you may see: Note: The information displayed is dependent on the system being used.
+---------------------------- COM Ports ----------------------------+
¦ COM1: COM2: COM3: COM4: ¦
¦ ----- ----- ----- ----- ¦
¦ Port Address 03F8H 02F8H 02E8H N/A ¦
¦ Baud Rate 1200 2400 57600 ¦
¦ Parity None None None ¦
¦ Data Bits 7 8 8 ¦
¦ Stop Bits 1 1 1 ¦
¦ Carrier Detect (CD) No No No ¦
¦ Ring Indicator (RI) No No No ¦
¦ Data Set Ready (DSR) No Yes Yes ¦
¦ Clear To Send (CTS) No Yes Yes ¦
¦ UART Chip Used 8250 16550AF 16550AF ¦
+-------------------------------------------------------------------¦
WARNING:
To determine the true Com Ports found on your system, refer to the Port Address displayed under the Com Port. The MSD.EXE utility scans your Com Ports sequentially. In the above example, the system has Com 1, Com 2 and Com 4. The information under COM3: is actually the information for Com 4. Refer to the following chart for Com Port Addresses:
PORT # ADDRESS DEFAULT IRQ
Com 1 03F8 4
Com 2 02F8 3
Com 3 03E8 4
Com 4 02E8 3
Using this chart with the example display above, we see that the address under COM1 is 03F8 and therefore correctly states the information for Com 1. The address listed under COM2 is 02F8 and therefore correctly states the information for Com 2. However we find that the address under COM3 is actually the address for COM4, and therefore the information in this column is actually for COM4. We can now safely conclude that you can NOT install a internal modem on COM1, COM2 or COM4. The only open Com Port for installing an Internal modem is COM3.
Note:
In the above example, if a mouse is using Com 1, DO NOT USE IRQ 4! This means you would need to use another IRQ like 5 or 7.
COMMON CONFIGURATION
As mentioned earlier, the most common configuration of Com Ports for computers is a Serial I/O card set to Com 1 and Com 2. If you install your Internal Modem to the factory default of Com 2, YOU WILL HAVE A HARDWARE CONFLICT!
Following is an example of this configuration with the easiest way to trouble shoot the problem WITHOUT removing the Internal Modem from the system if your model has Dip switches located below where you plug in the phone line (Most models have this feature):
+---------------------------- COM Ports ----------------------------+
¦ COM1: COM2: COM3: COM4: ¦
¦ ----- ----- ----- ----- ¦
¦ Port Address 03F8H 02F8H N/A N/A ¦
¦ Baud Rate 1200 2400 ¦
¦ Parity None None ¦
¦ Data Bits 7 8 ¦
¦ Stop Bits 1 1 ¦
¦ Carrier Detect (CD) No No ¦
¦ Ring Indicator (RI) No No ¦
¦ Data Set Ready (DSR) No Yes ¦
¦ Clear To Send (CTS) No Yes ¦
¦ UART Chip Used 8250 8250 ¦
+-------------------------------------------------------------------¦
If the MSD screen on your system displays information similar to the above example and the Internal Modem is already installed in the system set to Com 2, you can NOT tell if the I/O card and the Modem are both trying to use Com 2. Follow the instructions following to determine if the I/O card is set to Com 2.
1. Exit all software and TURN OFF your computer.
2. Change the Dip Switch settings(on the Zoltrix Modem) to select a Com Port not found by MSD.EXE. (In the above example you can select Com 3 or Com 4. Refer to manual or Quick Installation card for settings.)
3. After the Dip switches are changed, Turn on your computer.
4. Start the MSD.EXE program.
Refer to USING MSD.EXE TO DETERMINE COM PORT'S ON YOUR SYSTEM
If the address 02F8 is found, you can NOT set your Internal Modem to Com 2. You should set your modem to Com 3 or Com 4. Note: Remember to NOT share an IRQ with the mouse's Com Port!
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