Introducing the Buffalo Monitor

Buffalo is a so called resident program that provides capabilities useful in developing applications for the Motorola 68HC11 microcontroller.  The term resident means that the entire Buffalo program is present in the 68HC11 microcontroller system itself.  Bear in mind that for Buffalo to be useful as a tool, it must leave space for the actual application.  For this reason, Buffalo uses a simple ASCII terminal type interface.  The first rule to learn about Buffalo is it only understands numbers in hexadecimal format.  Do not use the prefix $ as you might normally to indicate that a number is in hexadecimal format.

The attached documents also introduce the Axiom AxIDE program that provides some assistance with the assembler and Buffalo.  As a side note, PC-Bug 11, J-BUG 11, and NoICE are some alternatives to Buffalo that you might wish to look at as well. 

To perform the experiment described in this document you will need the Axiom CME-11E9-EVBU development board, the University of Hartford 68HC11 Educational Board, or some other equivalent development board with the Buffalo monitor installed.  Also have on hand two relatively short wires, a light emitting diode (LED) and a 330 ohm or 390 ohm watt resistor.  Connect the wires, resistor, and LED as illustrated below such that the LED becomes illuminated when pin 4 in port A (PA4) becomes logic high.

Attaching an LED to the Axiom development board

Attaching an LED to the U.H. development board

An ASCII terminal or just about any ASCII terminal program can be used to communicate with Buffalo.  Hyper Terminal is provided with most versions of Windows.  As an alternative, Tera Term is a terminal program that is freely available on the Internet.

Buffalo starts by printing a greeting message and waiting for you to send a carriage return character.  If you don't see Buffalo's greeting, an adjust to the configuration register may be needed.  The Config. Register notes describe how to make such an adjustment.  Buffalo is command driven in that it reacts to commands that you type in.  Entering the command help at the prompt causes Buffalo to list all the commands it knows along with some additional information. 

Enter the help command. At this point the help display should look somewhat confusing to you.  Don't be alarmed; in the following we will examine many of the commands. 

Buffalo Help Display

Note that simply pressing the Enter key causes Buffalo to repeat the last command that was entered. 

Copyright Notice

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This tutorial page was written for EE332, the Introduction to Microprocessors course offered by the Electrical Engineering Department in the College of Engineering at the University of Hartford.  Copyright is dated October 18, 2001 and is reserved by the author, Jonathan Hill.  Permission is granted to make copies of this document for educational use as-is, provided that this statement remains attached.  I do strive to improve this document, so please forward constructive criticism for my review along with suggestions.  Credits will be added as improvements are made to this document.
Original Author: Jonathan Hill (
Last Modified: Fri Dec 13 17:05:34 EST 2002