The MC6809 cookbook

177 Pages·1981·5.372 MB·English

by  Warren, Carl D.

THE
MC6809
COOKBOOK
by carl d. warren
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TAB BOOKS Inc.
TAB
BLUE RIDGE SUMMIT. PA. 17214
FIRST EDITION
SECOND PRINTING
Copyright © 1980 by TAB BOOKS Inc.
Printed in the United States of America
Reproduction or publication of the content in any manner, without express
permission of the publisher, is prohibited. No liability is assumed with respect to
the use of the information herein.
Library of Congress Cataloging in Publication Data
Warren, Carl D
The MC6809 cookbook.
Includes index.
1. Motorola 6809 (Computer) I.Title
QA76.8.M67W37 001.64 80-23359
ISBN 0-8306-9683-0
ISBN 0-8306-1209-2 (pbk.)
is a trademark of Motorola Inc.
Contents
Acknowledgments 6
Preface 7
1 General Descriptions 9
Introduction to the 6809—Basics of the 6809 µP—High Level
Language Processor—Changed Configuration—The Right
Nomenclature—Variety in Clocks—6809 MPU Signal
Description—Pulling the Schmitt-Trigger—Tracing the
Interrupt—Establishing a System
2 6809 µP Software Architecture 25
The Software Tale—Registers, Pointers and Things—Condition
Codes Are Special—6800/6809 Software Incompatibilities-
Equivalencies—Performance Summary
3 Addressing Modes 37
Basic Concepts—Inherent Addressing Mode—Immediate
Addressing—Extended Addressing—Direct Addressing—
Register Addressing—Indexed Addressing—Indexed Indirect-
Relative Addressing—Summary
4 Into the Instruction Set 56
Push-Pull and Address It—Individual instructions
5 MEK6809EA Assembler 112
Basics of the Assembler—Typical Requirements—
Expressions—Symbols—Assembler Listing
6 Implementation of VTL-09 118
Direct and Program Statements—Preliminary Concepts—
Arithmetic Operations
Appendix A Motorola 6809D4 134
Highlights—Model Types—Expansion—Software Features—
Added D4B Software Features—MEK6809D4 Description—
MEK68KPD Description—Sample Programs
Appendix B Hexadecimal Values of Machine Codes 148
Appendix C Programmer's Card 153
Appendix D Instruction Index 169
Index 176
Acknowledgments
When any work such as this is embarked upon, it requires a
massive amount of support from a variety of sources. It was
necessary to rely upon the suggestions and resources of a number
of people and companies. Among these people are; Ron Denchfield
of AMI who supplied, most of the figures and the programmer's
card, Tim Ahrens, Bill Clendinning and Irwin Carroll of Motorola,
who provided various tables and important suggestions, along with
the 6809D4 evaluation unit.
Since this book is about computer technology, it is only ap
propriate that it was created with aid of a computer. The manu
script was prepared on a Heath H-89 microcomputer, and printed
on an Epson TX-80 dot matrix printer. The software that was used
consisted of a variety of products. Among these were the editor and
text formatter available from the Heath users' group (HUG), the
PIE editor from the Software Toolworks, and a very special pro
gram called COPY that permits interchanging software created
under HDOS to CP/M compatible files. This unique piece of magic
was created by Bob Mathias, a genius of our times. Other software
was supplied courtesy of Tony Gold at Lifeboat Assoc. These
consisted of Organic software's Textwriter III for text formatting
and Digital Research's CP/M optimized for a 4200H base.
Special thanks is reserved for the finest managing editor in the
magazine industry today, Jordan Backler. It is because of his
suggestions, coupled with those from fellow EDN editors Bob
Peterson, and Ed Teja, that this work is as concise as it is.
My wife Anne and daughter Tami played probably the most
important part in the creation of this book—putting up with the
writing process and making sure the coffee was always available.
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Preface
As a result of the profliferation of microprocessors (µP), since
1977 hardware and software designers have been able to extend
their capabilities in terms of creating useful products for everyday
life. Each day, new processor introductions are opening up even
more exciting vistas. Unfortunately, there is a problem associated
with the introduction of the newer devices: how to correctly use
them for maximum benefit and efficiency.
This book, like many of its type, attempts to give the engineer
or technician an expert command of the fundamentals of the 6809
microprocessor (µP), and the basic skills for writing 6809 assem
bly language level code. In systematic fashion, it proceeds from
analysis of the microprocessors design to its important electrical
characteristics. It continues with discussion on matters like inter
nal logic, comparison to the 6800, interfacing to peripherals,
software architecture, addressing techniques and the instruction
set. It concludes with advice on how to build or make use of
existing 6809 based systems. Further enhancing The MC6809
Cookbook's usefulness is the inclusion of a programmer's card,
provided courtesy of American Microsystems Inc. (AMI).
The MC6809 Cookbook may be studied as a course, proceed
ing from the simple to the more complex. However, it should be
more appropriate viewed as a reference source to be called upon as
necessary. Therefore, I have kept the idea of a compact and concise
reference work utmost in my mind while creating this book. As a
7
result of this goal, the diversified contents are readily identifiable
to facilitate the finding of specific principles or functions associated
with the 6809 µP.
The MC6809 Cookbook aims to be comprehensive without
being cumbersome. It seeks in all areas to be exact, clear and
succinct.
Throughout this book, µP, and µC are used to mean micro
processor and microcomputer, respectively. These are stylistic
nuances used at EDN magazine, and permit brevity without being
imprecise.
carl d. warren
8
General Descriptions
The 6809 /xP, developed by Motorola and second sourced by
American Microsystems Inc. (AMI), is a high performance mul-
tifaceted device. It is considered by many industry observers and
Motorola to be the interim processor between 8-bit and 16-bit
devices. The general design philosophy of the device seems to
support this conjecture in that it permits the handling of 16-bit
registers with powerful instructions.
INTRODUCTION TO THE 6809
The 6809 µP is unique because it represents an upward
growth device from the ubiquitous 6800 (µP. This upward growth is
in the form of software compatibility, at the source code level, and
apparent similar operation of the two devices.
As a result of these similarities, it is possible to design the
6809 µP into a variety of applications. Among these applications
are process control, automobile system monitoring, television
sets, intelligent terminals and other devices more far reaching than
this book could even begin to mention. As an example of the use of
the 6809 µP was recently incorporated into what will more than
likely become the small computer system of the decade, the Radio
Shack TRS-S0 Videotex (Fig. 1-1). This unit not only uses the 6809
/xP, but the entire spectrum of Motorola support and peripheral
chips. The point is that it shows the flexibility of the 6809 µP.
9