The Contest Computer (Cereal Ports-The Top Secret Plan)

W3MM at W3MM at
Sun Dec 24 22:53:36 EST 1995

It is now time to carve our game plan in something soft and mushy.
We don't want to carve it in stone since the first plan may not work
and we may have to come up with another plan.

Here we go!
1) COM1, IRQ4.  The serial mouse will reside on this serial port. A safe
    move, you bet.
2) COM2, IRQ3.  I like to use this serial port to connect to the network.
    This is the connection to the second computer that is controlling the
    second station.   The reason that I do this is that I have an A/B data
    switch in this serial connection that allows me to disconnect the
    2nd computer and connect the port to an external modem.
3) COM5, IRQ10.  We shall use this serial port to talk to the computer
    controlled radio.
4) COM6, IRQ11.  We shall use this port to talk with the packet TNC.  

We now have a game plan.  We just have to implement the plan with
hardware and software.  Remember that we only have two physical
ports in the computer at this time.  We need two more physical ports.
That is where the 4 port com card is going to help us.  Also you must
keep in mind that DOS only supports com1-4.  What this means is 
that the contest logging software must provide support for com5-8.

Now I must go back in time and talk about the UART.  The preferred
UART on a serial port is one in the 16550 series.  Remember that I 
asked you to run MSD and make a note as to what type of UART is
used in your serial ports.  The 16550 UART has a small amount of
buffering built into it.  What is a buffer?  A buffer is a storage device
to compensate for differences in speeds of peripheral devices or events
being monitored by the computer.  This W3MM goof just said that my
serial ports may be running at different speeds.  No worry mate, the 
computer can sort it out.  Remember that the CPU can only talk to
one device at a time so the buffer gives the CPU a little extra time to
get the data from a serial port.   The idea is that we do not want to
                             lose any data.  

Since I have been using computers with 16550 serial ports for my
contest logging operations, I no longer experience computer lockups
and the two computers have the same score at the end of the contest. 
I don't have to fool with merge programs to get both computers to 
agree on the final score. 

My computer does not have 16550 UART's.  Do not worry about it.
The 4 port serial card will take care of this.   The 4 port card has a 
16550 UART for each port.  All you have to do is disable the ports
that are on your hard drive controller card or if the ports are on the 
motherboard disable them in the BIOS setup.  The 4 port card card
also has two lpt ports that are the latest and greatest and offer 
bi-directional or the old style uni-directional capability.  Remember 
that you can also disable those old style lpt ports.   Do you want
to put some new zing into the confuser?  Read on.

Here is a 4 port card that works as expected and also where to get it:

Vendor:  Byte Runner Technologies     Phone: 800-274-7897
             406 Monitor Lane
             Knoxville, TN 37922
Product Code:  9006-S5-4    4-port card with 4 16550's, 2 bi-directional
                                          parallel ports

Price:  $89.95 plus $7.50 for 2 day air shipping.

Well I think that we have flogged the serial ports into submission.  The
next post will deal with how we connect the external devices to the 
serial ports.

VY 73 de Dave  W3MM  w3mm at

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