How to make COM3/4
                          work on the computer
                          ====================

Most computers work with COM1 and COM2 no problems. The addresses and
interrupts follow:

COM 1    IRQ 4    3F8
COM 2    IRQ 3    2F8

Now when you add COM 3 and 4, it looks like this:

COM 3    IRQ 4    3E8
COM 4    IRQ 3    2E8

Notice that COM 3 and COM 4 share the same IRQ lines as their counterparts
in COM 1 and COM 2. This is where most applications will fail and lock up.
To prevent this, you must reassign the interrupt leaving the address the
same.
To do this, you need to know the pinout of the IRQ lines on the edgecard
connector of the serial board as well as a piece of scotch tape and a short
length of wire. Some soldering is involved.

In the following example, it is assumed that IRQ 2 is not used for anything
at present on your computer. You should use a program such as QA PLUS or
a Norton Utility to find out what how your interrupts are assigned on your
computer. It may not be the same for each computer.

Modifications:
--------------
Step:

1)   Locate the IRQ 4 line on the board you want to use for COM3/4. To do this
     you put the serial board down, COMPONENT SIDE DOWN on the table. The
     foil side is now up.

2)   IRQ 4 is on pin 24. There are 31 fingers on each side of the board. If
     your board is not marked for pin 1, you can do this to find it. Count
     down 4 pins from the end of the board. If there is a connection there,
     chances are that you are on the wrong end of the board. That is the ALE
     line. Go to the other end of the board and count down 4. It should be
     unconnected. That is the IRQ 2 line. (Almost never used in a $25 serial
     card). Note that this is referred to as pin 4.
     Put a piece of scotch tape on pin 24. Make sure it doesnt overlap any
     other fingers. Solder a wire from the top edge of the finger (away from
     the edge of the board) on pin 24 and solder the other end to pin 4. If
     you are unluck to not have a finger on pin 4, you will have to improvise.
     A couple ways : buy some copper tape (Adhesive one side) and make your
     own finger;  or buy a conductive ink pen and draw a conductive finger on
     the board. The pens can be purchased at most electronic outlets.
     Repeat the above procedure for COM 4 and a different IRQ line if
     you have any un-used ones left. Refer to the table below for more info.

3)   Configure you com board for IRQ 4 and COM 3.

That is all there is to it.
   Now to determine what you should plug into COM 1 2 3 and 4, will be
   dependent on the software and serial hardware you want to plug in.
   For example, if you mouse doesnt support com 3, then you are stuck
   plugging it into 1 or 2. If you want to use YAPP and it doesnt support
   com 3, you must put it on com 1 or 2. If your modem program DOES support
   Com 3 and can be IRQ programmed (like TELIX), then you CAN use you modem
   on COM 3. Don't plug it into COM 1 since it would waste that slot.

Other pins and IRQ lines on the PC board:

IRQ      Pin #
2         4
3         25
4         24
5         23
6         22
7         21

PS: I have installed the above mods in my 386 and 286 computers and worked first

time.
ning simultaneously.