Contents of the IS16550.DOC file
Copyright (C) 1989 George A. Stanislav.
All Rights Reserved.
IS16550.COM is a simple utility to determine if the UART in the serial port
of your PC is the new NS16550AN. The advantage of this chip, for the PC user,
is in its internal buffer which is important for the new fast machines,
especially those built around the 80386 microprocessor.
One simple method of determining what type of UART your machine contains is
to open the computer, pull out the serial card and read the inscription off
the UART chip. Unfortunately, this is not always possible (as when you are
buying a computer from an ignorant salesman).
Instead, running a simple program to determine the type of UART in the system
serial port is a better solution.
IS16550 will determine whether an NS16550AN UART is installed in a system. It
can check serial ports COM1 - COM4. If you do not specify the port(s), COM1
will be checked. You can specify one or more serial ports in one run of the
For example, if your system has two serial ports, you could enter:
IS16550 at COM1 and COM2 ?
Yes, you can type it as a whole sentence if you wish. Or you can make it as
to check all four ports.
Note that there exists an NS16550 UART. This one has all the advantages of
the NS16550AN, except for the buffers. The IS16550 program can distinguish
between the two and will suggest a replacement if it detects the older chip.
Full assembly language source code is enclosed for anyone interested in the
detection of the presence of the NS16550AN UART.
This program is offered as is, with absolutely no guarantee whatsoever.