68000 assembly language programming and interfacing

- a unique approach for the beginner -

by Ambrose "Bo" Barry, P.E.

(free software disk available - see below)

Are you reluctant to introduce or study microcomputer programming and interfacing because all of the so-called elementary texts seem to be for a well-prepared engineering student?

Are you reluctant to introduce either a software or hardware course for the beginner due to the lack of economical hardware or software?

Are you STILL teaching the Motorola MC6800, introduced in 1974? If so, are you professing that "If you learn an 8 bit computer, you can learn a 16 bit computer by yourself"? Are car mechanics taught how to fix T-Models, and then are expected to fix T-Birds? Stop and think of the value of having the MC6800 in one's resume, as opposed to the MC68000 or MC68040.

If the reluctance to teach a modern (and very sophisticated) computer system has been due to the lack of a suitable text, or due to the excessive costs of hardware or software, then consideration of 68000 assembly language programming and interfacing - a unique approach for the beginner is a must.

Following is an excerpt from the text preface:

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About This Book

This book is about the Motorola 68000 microprocessor, with emphasis on its programming and interfacing. It presents the material, thru an informal style, by introducing a series of examples, each of increasing complexity. The purpose of the book is to provide a background in both the software programming and hardware interfacing of a typical and powerful microprocessor.

The unique aspect of this book is that it is NOT another "Programming Manual", with nothing but pages upon pages of explanations of the operations of each and every instruction, with scant or meaningless examples.

Intended Audience Of This Book

This book is intended as an introductory book for anyone interested in computer programming and/or interfacing. It is ideally suited for a curriculum in two year engineering technology programs. Its goal is to introduce the material in such a way as to replace the Motorola 6800 which is STILL being taught to beginners. The book is NOT a complete treatise on the 68000 and is not a computer DESIGN text.

A 16/32 bit microprocessor was chosen as the entry level rather than the conventional 8 bit devices which are still deeply entrenched in industrial applications. The 68000, despite its complexity and power, is a 'clean' device to learn, and provides a good starting point for future developments in this rapidly changing area. For applications where an 8 or 4 bit device is more aptly suited, the 'backward' learning process is much easier after coverage of the 68000. While increasingly sophisticated industrial developments are best suited by a 32 or 16 bit uP, MANY and probably MOST applications will ALWAYS be best suited for an 8 (or 4) bit uP. This fact is often the driving force on what type microprocessor is taught in the college environment. However, mention of only 8 bit experience in one's resume is looked at BY MANY as an indication of obsolescence.

The study of microprocessor architecture, assembly language programming, and interfacing techniques is an integral part of electrical and computer engineering technology curricula. This field of study does not have to be limited to the electrical/computer-inclined, however. The microprocessor is a powerful and fascinating device and can be conquered by anyone with an inquisitive mind (or an industrial need). Creativity and common sense assist the learning process as well. Little or no computer or digital logic background is needed.

How To Use This Book

This book is a combination textbook/laboratory manual, providing material for both classroom instruction and individual laboratory experimentation. The first 5 chapters are intended for either a review, an initial brief survey, or later reference. Work actually starts with Chapter 6, with introduction of the first example. Instructions and techniques are introduced in chapters 6 thru 9 as they are needed in order to complete the examples. A complete alphabetical listing of the 68000's instructions is included in the last chapter, along with details on actual execution of a portion of the examples on the three hardware and software systems mentioned below.

Required Support Material

You should use the book with one of the following:

1) The PseudoCorp PseudoMax and PseudoSam cross assembler and simulator programs. (A student version is available for those adopting the text, from Prentice Hall or from the author.).

2) The Motorola 68000 Educational Computer Board (ECB).

3) Micro Board Designs MAX 68000 microcomputer system. This economical computer board is highly recommended, and is easy to interface and use.

In addition, a MS-DOS computer is needed in order to utilize the PseudoCorp software and to connect to the two hardware systems. Alternatively, another type personal computer could be used with a compatible cross assembler/simulator and a terminal program to connect to the two hardware systems.

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If you would like more information about this innovative text, designed for the beginner, contact Prentice Hall at (201) 461-4544 (or 461-4876). The author can be contacted at the Engineering Technology Department at the University of North Carolina - Charlotte, Charlotte, NC 28223 or via telephone at (704) 547-4185 or (704) 455-6153 (evenings).

A demo disk setup, ready-to-run, is available from the author. It is available on one 3.5" 1.44MB disk, or on one 5.25" 1.2MB disk, or two 5.25" 360K disks, and a donation of $1 is requested to defray costs. (Information on the complete software offering is outlined in the text.)