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6800 Programming for Logic Design By Adam Osborne Copyright 1977 This description contains and overview of the book, a list of the table of contents and a review of the book by Jeff Grossman from The Best of Creative Computing, Volume 3. Introduction This book explains how an assembly language program within a microcomputer system can replace combinational logic- that is, the combined use of "off-the-shelf," non-programmable logic devices, such as standard 7400 series digital logic. If you are a logic designer, this book will teach you how to do your old job in a new way- by creating assembly language programs within a microcomputer system. If you are a programmer, this book will show you how programming has found a new purpose- in logic design. This is a "how to do it" book; as such, it has to become very specific, so a particular type of microcomputer, the MC6800, is referenced directly. Companies manufacturing these microcomputers are: Motorola. Incorporated Semiconductor Products Division 3501 Ed Bluestein Boulevard Austin, Texas 78721 American Microsystems 3800 Homestead Road Santa Clara, California 95051 What This Book Assumes You Know This book is a sequel to An Introduction To Microcomputers , which was a single volume in its first edition, but is two volumes in its second edition. An Introduction To Microcomputers describes microprocessors and microcomputers conceptually; it does not address itself to the practical matter of implementing a concept. This book addresses the practical matter of implementation. In that this book is a sequel, it makes a single assumption- that you have read, or you otherwise understand the material covered in An Introduction To Microcomputers. However, before launching into a real design project, you will need vendor literature that specifically describes the devices you have elected to use. Note in particular that hardware and timing are not described in this book, either for the MC6800 CPU, or any other microcomputer devices; sufficient information may be found in An Introduction To Microcomputers, Volume II- Some Real Products. The MC6800 instruction set is described in Chapter 6 of this book, since programming is what this book is all about. Understanding Assembly Language Assembly language instructions are the transfer functions of a microcomputer system; taken together, they constitute an "instruction set," which describes the individual operations which the microcomputer can perform. You define the events which must occur within the microcomputer system serially- as a sequence of instructions, which, taken together, constitute an assembly language program. In reality, understanding what individual instructions do within a microcomputer system is very straightforward; it is one of the simplest aspects of working with microcomputers. Yet it unduly terrifies users who are new to programming. If that includes you, a word of advice - forget about mnemonics and instruction sets; take instructions one at a time as you encounter them in this book. When you do not understand what an instruction is doing, look it up in Chapter 6. The specter of "programming" will haunt you only if you let it. How This Book Has Been Printed Notice that text in this book has been printed in boldface type and lightface type. This has been done to help you skip those parts of the book that cover subject matter with which you are familiar. You can be sure that lightface type only expands on information presented in the previous boldface type. Therefore, only read boldface type until you reach a subject about which you want to know more, at which point start reading the lightface type. Table of Contents 1) Introduction 2) Assembly Language and Digital Logic 3) A Direct Digital Logic Simulation 4) A Simple Program 5) A Programmer's Perspective 6) The MC6800 Instruction Set 7) Some Commonly Used Routines Review of 6800 Programming for Logic Design by Adam Osborne Review by Jeff Grossman This review was published in the 1980 book, The Best of Creative Computing, Volume 3 on page 305.   6800 Programming for Logic Design. Adam Osborne. Adam Osborne and Associates, Inc. 289 pp., paperback. $7.50, 1977. With all the largely worthless books being published about microprocessors and microcomputers, it is refreshing to find one that sets its goals short of solving all the world's problems, and then meets these goals with a clarity, conciseness, and competence not often found in other books on the same subject. Author Osborne's intent is to show how assembly-language programs, in microprocessors, can replace discrete logic components. This is explained in the context of the Motorola 6800, but is applicable to almost any microprocessor. In seven chapters, the last two of which are 6800 reference material, the reader is guided from software simulation of gates to digital-system implementation via programming. Osborne begins by showing how simple gates and flip-flops can be replaced by small segments of assembly-language code.  He then points out that using a microprocessor to replace a gate or a flip-flop is wasteful, and presents an example of replacing an entire circuit with a microprocessor.  The circuit, used throughout the book, is an excellent vehicle for getting concepts across.  The circuit is taken from an actual product, the Qume daisy-wheel printer, and provides a mixture of synchronization, timing delay, and control problems that manages to illustrate most of the major issues in this type of design.  Again the reader is told that all is not perfect.  The assembly-language program, while functionally correct, is really a direct gate and flip-flop emulation of the print-wheel and hammer-control circuit.  This is generally not the best approach as such a direct simulation of a working digital circuit may not work due to unsuspected timing dependencies, lack of parallelism, etc.  The circuit is then re-implemented, ignoring the gates and, instead of concentrating on providing the functionality of the original circuit and preserving its input/output relationship.  But the author is not finished yet.  He describes a third, and final, program with some optimizations revealed by examining the problem from a software viewpoint. A unique feature of this book is that it is printed in boldface and lightface type.  The boldface type (more sparse) presents the key ideas, while the lightface type expands upon them.  Thus the reader can skip the detailed explanations when not required, but, upon reaching an unfamiliar topic, will find sufficient detail to answer most questions.  The only criticism is that the diagrams tend to be somewhat cluttered.  Particularly annoying is the practice of drawing arrows directly on assembly-language and diagram text to illustrate a point.  This, however, is a minor problem in an otherwise fine book. The author assumes a knowledge of basic microprocessor principles.  In practice, someone with a background in elementary combinational and sequential circuits and some form of programming will be able to benefit from this book.  6800 Programming for Logic Design is not for those who get their thrills by playing Spacewar, but anyone who designs microprocessor systems, or who is interested in doing so, will find this book interesting, informative, and useful. Jeff Grossman Cambridge,MA

1Love Letters of Dorothy Osborne

By Dorothy Osborne

A lively, interesting and important collection of 17th century love-letters written by an English lady, against the background of the Civil War and the Restoration [summary by hefyd]<BR><BR>After refusing a long string of suitors put forth by her family, including her cousin Thomas Osborne, Henry Cromwell (son of Lord Protector Oliver Cromwell) and Sir Justinian Isham, in 1655 Dorothy Osborne married Sir William Temple, a man with whom she had carried on a lengthy clandestine courtship that was largely epistolary in nature. It is for her letters to Temple, which were witty, progressive and socially illuminating, that Osborne is remembered. Only Osborne's side of the correspondence survived and comprises a collection of seventy-seven letters held in the British Library. (Summary from Wikipedia)<BR><BR>Note: This reading contains all the letters in the correspondence but leaves out the editorial comments.

2Lion's Brood

By Duffield Osborne

"Centuries come and go; but the plot of the drama is unchanged, and the same characters play the same parts. Only the actors cast for them are new." For this timeless tale, we are taken back to the Roman forum. With the backdrop of the Punic Wars, we follow the fortunes of Sergius, a young man going off to serve and who impresses his general; and Marcia, the young woman he leaves behind, whom he loves, but who refuses to commit to any attachment for him before he leaves.

Welcome back to another exciting issue of the exciting and chilling magazine The Thrill Book, noted precursor to Weird Tales Magazine! In this, issue #6, we have two crackling serials: the first part of the terrifying haunted room story "The Crawling Hands" and the dashing conclusion of the sea-faring adventure yarn "The Devil's Own". Also included is the modern occult magic tale "Magic in Manhattan", the mysterious ghost story "From Over the Border", the creepy crawly "When Basset Forgot", the fantastical "The Rim of the World" and much more! Grab your gear and keep a light burning... It's time to take a trip into The Thrill Book! - Summary by Ben Tucker